Re: [FFmpeg-user] Cutting out part of a video does not work
Bo Berglund writes: > On Sat, 27 Mar 2021 10:06:03 +0100, Peter White > wrote: > >>> But it all looks the same with the time incrementing at exactly 5 seconds... >> >>Looks like someone took extra care to have a static keyframe interval. >>One can do that. With default codec options x264 won't produce such >>output though. >> > > The source is using a youtube URL for the streaming video and I use either > youtube-dl or ffmpeg directly to get it in my scripts. > > Is the fact that the times are so exact indication of recoding by Youtube, or > is > the source like that? > I really have no idea how Youtube video streaming works, I just use YouTube if > that is the source... > And I have never published any video on Youtube so I don't know the process. I know from experience that Youtube automatically transcodes uploaded videos from unpaid sources (e.g. me). It likely does the same for paid sources. After all, youtube streams at various resolutions, etc. Leo ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, Mar 27, 2021 at 05:18:18PM +0100, Bo Berglund wrote: > On Sat, 27 Mar 2021 10:06:03 +0100, Peter White > wrote: > > >> But it all looks the same with the time incrementing at exactly 5 > >> seconds... > > > >Looks like someone took extra care to have a static keyframe interval. > >One can do that. With default codec options x264 won't produce such > >output though. > > > > The source is using a youtube URL for the streaming video and I use either > youtube-dl or ffmpeg directly to get it in my scripts. > > Is the fact that the times are so exact indication of recoding by Youtube, or > is > the source like that? I believe this has to do with multi-bitrate streaming. I have recently read some guidelines about preparing videos for that. One recommendation is to use rather small GOP (group of pictures) sizes, thus small keyframe intervals. Some go as far as recommending static GOP sizes. From my understanding it is not a hard requirement. Like cutting, one can only switch to a different stream, from 720p to 1080p, on a keyframe, hence above recommendation for short intervals. > I really have no idea how Youtube video streaming works, I just use YouTube if > that is the source... > And I have never published any video on Youtube so I don't know the process. Then you need not bother with keyframe intervals. Let the codec make the decisions, which gives a rather good tradeoff between seekability (keyframe interval) and size. The more unnecessary keyframes there are, maybe even at fixed intervals, the more wasteful is the result, as in bigger than necessary. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, 27 Mar 2021 10:06:03 +0100, Peter White wrote: >> But it all looks the same with the time incrementing at exactly 5 seconds... > >Looks like someone took extra care to have a static keyframe interval. >One can do that. With default codec options x264 won't produce such >output though. > The source is using a youtube URL for the streaming video and I use either youtube-dl or ffmpeg directly to get it in my scripts. Is the fact that the times are so exact indication of recoding by Youtube, or is the source like that? I really have no idea how Youtube video streaming works, I just use YouTube if that is the source... And I have never published any video on Youtube so I don't know the process. -- Bo Berglund Developer in Sweden ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, Mar 27, 2021 at 09:13:10AM +0100, Bo Berglund wrote: > On Sat, 27 Mar 2021 02:50:13 +0100, Peter White > wrote: > > >> I tested your command ona typical video file and found that the output > >> looks > >> basically like this: > >> > >> [FRAME] > >> best_effort_timestamp_time=3900.00 > >> [/FRAME] > >> [FRAME] > >> best_effort_timestamp_time=3905.00 > >> [/FRAME] > >> [FRAME] > >> best_effort_timestamp_time=3910.00 > >> [/FRAME] > >> [FRAME] > >> best_effort_timestamp_time=3915.00 > >> [/FRAME] > >> > >> It seems like there are "frames" at every 5 seconds. > > > >Not to be picky, but there are certainly very many more frames. The > >distinction is between *keyframes* and everything else called a frame. > > > Of course this is not the entire output! It streams past at high speed so > covers > many many pages. That I did understand. I just wanted to be extra clear that there most certainly are many more *non-key* frames between those keyframes listed above, usually motion pictures have at least 24 frames per second. > But it all looks the same with the time incrementing at exactly 5 seconds... Looks like someone took extra care to have a static keyframe interval. One can do that. With default codec options x264 won't produce such output though. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, Mar 27, 2021 at 09:39:38AM +0100, Cecil Westerhof via ffmpeg-user wrote: > Bo Berglund writes: > > > Worth a check of your computer. > > It should be able to run at 100% CPU for quite a while in normal > > surroundings > > (if the air flow is not obstructed, please check the inlets on the > > underside of > > the laptop). > > Running ffmpeg with 100% CPU is not a problem. But running mpv with > 60% CPU is. I find this quit weird. That is quite unusual. Are you by any chance using hardware acceleration in mpv? 60% CPU tells me, the answer is probably no, but maybe it is yes and can explain overheating because GPU usage is not prominently reported, so you might not see that the actual heat is caused by a busy GPU not the CPU. Anyway, overheating and shutdown because of it definitely points to a problem in your cooling. But this is out of scope for this mailing list, I guess, since it is unrelated to ffmpeg. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, Mar 27, 2021 at 08:29:26AM +0100, Cecil Westerhof via ffmpeg-user wrote: > Peter White writes: > > > On Sat, Mar 27, 2021 at 06:18:59AM +0100, Cecil Westerhof via ffmpeg-user > > wrote: > >> Peter White writes: > >> > >> > On Fri, Mar 26, 2021 at 05:28:40PM +0100, Cecil Westerhof via > >> > ffmpeg-user wrote: > >> >> Peter White writes: > >> >> > >> >> > On Fri, Mar 26, 2021 at 09:55:21AM +0100, Cecil Westerhof via > >> >> > ffmpeg-user wrote: > >> >> >> I want to publish a speech I gave during a Zoom meeting. But cutting > >> >> >> it out does not work. > >> >> >> > >> >> >> When I use: > >> >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to > >> >> >> 1631 > >> >> >> -acodec copy -vcodec copy -async 1 speech.mp4 > >> >> >> > >> >> >> The video starts just a bit to late. But when I use: > >> >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to > >> >> >> 1631 > >> >> >> -acodec copy -vcodec copy -async 1 speech.mp4 > >> >> >> > >> >> > > >> >> > If you can live with further quality loss in the video, you can > >> >> > transcode it, i.e. -c:v libx264. > >> >> > > >> >> > >> >> I now use: > >> >> ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 -to 442 > >> >> -acodec copy -vcodec libx264 -crf 8 -async 1 speech.mp4 > >> > > >> > CRF 8 seems excessive. Try 16 for a start. From various online sources I > >> > gathered that it is pretty much transparent, as in no noticeable > >> > difference to the original. My own experience shows the same. > >> > >> So crf is useful? (Other post said not.) I am now running it without > >> crf (and async). When it is finished I will try it with crf 16. > > > > I am pretty certain Carl Eugen also meant that CRF 8 is excessive for > > no visible gain in quality. From the documentation of x264 I remember > > that an decrement of 1 results in a size increase of the video of > > roughly 12.5 %, so when you use 8 instead of 16 that is 1.125 to the > > power of 8 the size of the same video encoded with CRF 16, so roughly > > 2.5 times the size. And you won't notice the difference. Might even try > > higher values for CRF. Since I, personally, are very conscious about not > > losing any quality, I use 16. But even that might be too conservative. > > Consider it a rough ball park figure to get you started. > > Before working with the video I narrowed it. Do you mean, that you already transcoded it before cutting? That should be avoided, because of the propagation of losses. > (If I do not my processor gets to hot and the computer shuts down.) You should do something about cooling then. Or, since you are using Debian, you could use the powersave CPU frequency governor, i.e.: # cpupower -c all frequency-set --governor powersave This should mitigate the overheating issue for the time being, but it will most certainly slow down the encoding process. > There I use crf 23, maybe I should redefine that to 16. CRF 23 should run a bit faster since the codec takes some more "shortcuts". At least that is my experience. If the quality is acceptable, that is perfectly fine. As I said, I am rather conservative in that regard. > >> >> This takes about 8 minutes instead of a second. But I have to live > >> >> with that. > >> > > >> > You could try to do this in multiple stages, maybe. Only transcode the > >> > first few seconds up to the next keyframe and then stitch that and the > >> > copied rest together. In theory this should work, but may be not as easy > >> > to achieve. Obviously the codecs, frame rates and resolutions need to > >> > match. I guess codec parameters need to match as well, not sure. The > >> > question is if it is worth the effort. > >> > >> I was thinking about a variant of this. Create a few seconds of the > >> start and a few seconds of the end until I entered the correct values > >> and then generate the complete file. > > > > Don't worry about the end, because there is no restriction on what kind > > of frame is allowed there. The encoder will simply stop encoding. > > I need to. ;-) If it is wrong I need to enter a better one an convert > again. What I mean is: you do not need to take extra care for the end of the video, not even with the copy codec, because there is no restriction on the frame type for the end. The reason for having to start on a keyframe is that only that type of frame is an actual full picture. Others following and referencing a keyframe basically only contain the differences, greatly reducing the size. Since the last frame must have a keyframe somewhere before itself, there is no problem, because the whole picture can be reconstructed. And if you only need to cut something off the end, but the start is correct, you can simply use the copy codec. The problem (keyframe) only exists, if you need to use -ss, which won't be the case for trimming the end. > >> It seems that without crf the video is generated faster. It now only > >> took five minutes. (But maybe my
Re: [FFmpeg-user] Cutting out part of a video does not work
Bo Berglund writes: > On Sat, 27 Mar 2021 08:29:26 +0100, Cecil Westerhof via ffmpeg-user > wrote: > >>Before working with the video I narrowed it. (If I do not my processor >>gets to hot and the computer shuts down.) There I use crf 23, maybe I >>should redefine that to 16. >> > I also encountered overheating and shutdown when using ffmpeg. The problem is not ffmpeg, but playing videos with mpv. Especially if Firefox is also running. > Turns out I had to blow out all of the dust accumulated inside the cooling > system on my HP 8440w with compressed air. After that the computer did no > longer > shut down even though it revved up the fan to max. Did already look at that, but seems OK. > Worth a check of your computer. > It should be able to run at 100% CPU for quite a while in normal surroundings > (if the air flow is not obstructed, please check the inlets on the underside > of > the laptop). Running ffmpeg with 100% CPU is not a problem. But running mpv with 60% CPU is. I find this quit weird. -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, 27 Mar 2021 08:29:26 +0100, Cecil Westerhof via ffmpeg-user wrote: >Before working with the video I narrowed it. (If I do not my processor >gets to hot and the computer shuts down.) There I use crf 23, maybe I >should redefine that to 16. > I also encountered overheating and shutdown when using ffmpeg. Turns out I had to blow out all of the dust accumulated inside the cooling system on my HP 8440w with compressed air. After that the computer did no longer shut down even though it revved up the fan to max. Worth a check of your computer. It should be able to run at 100% CPU for quite a while in normal surroundings (if the air flow is not obstructed, please check the inlets on the underside of the laptop). -- Bo Berglund Developer in Sweden ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, 27 Mar 2021 02:50:13 +0100, Peter White wrote: >> I tested your command ona typical video file and found that the output looks >> basically like this: >> >> [FRAME] >> best_effort_timestamp_time=3900.00 >> [/FRAME] >> [FRAME] >> best_effort_timestamp_time=3905.00 >> [/FRAME] >> [FRAME] >> best_effort_timestamp_time=3910.00 >> [/FRAME] >> [FRAME] >> best_effort_timestamp_time=3915.00 >> [/FRAME] >> >> It seems like there are "frames" at every 5 seconds. > >Not to be picky, but there are certainly very many more frames. The >distinction is between *keyframes* and everything else called a frame. > Of course this is not the entire output! It streams past at high speed so covers many many pages. But it all looks the same with the time incrementing at exactly 5 seconds... -- Bo Berglund Developer in Sweden ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Peter White writes: > On Sat, Mar 27, 2021 at 06:18:59AM +0100, Cecil Westerhof via ffmpeg-user > wrote: >> Peter White writes: >> >> > On Fri, Mar 26, 2021 at 05:28:40PM +0100, Cecil Westerhof via ffmpeg-user >> > wrote: >> >> Peter White writes: >> >> >> >> > On Fri, Mar 26, 2021 at 09:55:21AM +0100, Cecil Westerhof via >> >> > ffmpeg-user wrote: >> >> >> I want to publish a speech I gave during a Zoom meeting. But cutting >> >> >> it out does not work. >> >> >> >> >> >> When I use: >> >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 >> >> >> -acodec copy -vcodec copy -async 1 speech.mp4 >> >> >> >> >> >> The video starts just a bit to late. But when I use: >> >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 >> >> >> -acodec copy -vcodec copy -async 1 speech.mp4 >> >> >> >> >> > >> >> > If you can live with further quality loss in the video, you can >> >> > transcode it, i.e. -c:v libx264. >> >> > >> >> >> >> I now use: >> >> ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 -to 442 >> >> -acodec copy -vcodec libx264 -crf 8 -async 1 speech.mp4 >> > >> > CRF 8 seems excessive. Try 16 for a start. From various online sources I >> > gathered that it is pretty much transparent, as in no noticeable >> > difference to the original. My own experience shows the same. >> >> So crf is useful? (Other post said not.) I am now running it without >> crf (and async). When it is finished I will try it with crf 16. > > I am pretty certain Carl Eugen also meant that CRF 8 is excessive for > no visible gain in quality. From the documentation of x264 I remember > that an decrement of 1 results in a size increase of the video of > roughly 12.5 %, so when you use 8 instead of 16 that is 1.125 to the > power of 8 the size of the same video encoded with CRF 16, so roughly > 2.5 times the size. And you won't notice the difference. Might even try > higher values for CRF. Since I, personally, are very conscious about not > losing any quality, I use 16. But even that might be too conservative. > Consider it a rough ball park figure to get you started. Before working with the video I narrowed it. (If I do not my processor gets to hot and the computer shuts down.) There I use crf 23, maybe I should redefine that to 16. >> >> This takes about 8 minutes instead of a second. But I have to live >> >> with that. >> > >> > You could try to do this in multiple stages, maybe. Only transcode the >> > first few seconds up to the next keyframe and then stitch that and the >> > copied rest together. In theory this should work, but may be not as easy >> > to achieve. Obviously the codecs, frame rates and resolutions need to >> > match. I guess codec parameters need to match as well, not sure. The >> > question is if it is worth the effort. >> >> I was thinking about a variant of this. Create a few seconds of the >> start and a few seconds of the end until I entered the correct values >> and then generate the complete file. > > Don't worry about the end, because there is no restriction on what kind > of frame is allowed there. The encoder will simply stop encoding. I need to. ;-) If it is wrong I need to enter a better one an convert again. >> It seems that without crf the video is generated faster. It now only >> took five minutes. (But maybe my computer was doing less.) It is a lot >> smaller: 41.5 MB instead of 147.8 MB. > > Have a look at the defaults of the x264 encoder. If memory serves, CRF > is 23 by default and you will most certainly notice artifacts, > especially since you are transcoding from one lossy format to another, > because losses propagate. > >> Now trying with crf 16. And then comparing the video quality. > > You will see a difference between not specifying CRF and 16. I am pretty > sure about that. ;) I did not, but that is probably because I already did a conversion with crf 23. -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Peter White writes: > On Sat, Mar 27, 2021 at 05:53:56AM +0100, Cecil Westerhof via ffmpeg-user > wrote: >> Peter White writes: >> >> > On Fri, Mar 26, 2021 at 07:02:13PM +0100, Cecil Westerhof via ffmpeg-user >> > wrote: >> >> Carl Zwanzig writes: >> >> >> >> > On 3/26/2021 9:28 AM, Cecil Westerhof via ffmpeg-user wrote: >> >> >> There is only one problem. The video is 7:21 long, but both mpv and >> >> >> vlc think it is 7:30 long. >> >> > >> >> > IME, the metadata length often lies. When you say it's 7:21, is that >> >> > exactly how long it plays for or how long it ought to be? >> >> >> >> I almost never have this. (If I remember well, only with videos >> >> created with ffmpeg. Sometimes it started on a negative timestamp >> >> instead of 00:00:00.) >> >> >> >> Looking at the -to you would expect 7:22, but when I just play it, it >> >> ends at 7:21. >> > >> > You can try using -to as an input option as well. I am not sure, but I >> > seem to remember having similar problems once. Also, have a look at -t >> > for defining the length of the file as opposed to cutting on time code. >> >> That is what I did first. Then I got 1:34:19 (or something like it). >> So even worse. > > When you say "first", was that with -vcodec copy? Because that might > explain it. Although, I do not know why the file would be so much > longer. May be that data stream. No, libx264. What I think happened that the input was stopped, but the timestamp copied from the original. But I will keep playing with it. By the way when I crop the video afterwards the end time is correct. But it would be better to do everything in one swoop of-course. (At the moment I am just finding out what to do.) > BTW, you can use "time codes" for -ss, -to and -t, too. Personally, I do > not like having to calculate in seconds when I can simply use the > timestamps shown by a player. It is much more intuitive, to me at least, > to just say: cut from (-ss) 19:45 -to 27:11 instead of from 1190 to > 1631. But that, of course, depends on how you retrieved those timestamps > in the first place. Well I enter them as timestamps and my script convert it to seconds. (It is quit an old script.) And when I use the first as input and the second as output I need to convert them so I can calculate the length. > From my understanding the difference between them being used as input or > output options, respectively, is that when used as input options they > tell the *demuxer* to seek and stop at the given timestamps. Or, more > precisely, the demuxer seeks to the last keyframe before the -ss > timestamp and the decoder starts decoding from there, discarding all > frames before the accurate timestamp. That was my understanding also. -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, Mar 27, 2021 at 05:53:56AM +0100, Cecil Westerhof via ffmpeg-user wrote: > Peter White writes: > > > You can compile it yourself as well. It is not that difficult. Might > > need to hunt down some libraries, but that is basically just looking at > > the error messages of configure and finding the appropriate packages. > > Also, config.log and apt-file can help a great deal. > > I will look into that also. I only just remembered that there is a shortcut you can use: # apt-get build-dep ffmpeg The command will install all build dependencies which are required for the building the official Debian package. That should at least be a good start. ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, Mar 27, 2021 at 06:18:59AM +0100, Cecil Westerhof via ffmpeg-user wrote: > Peter White writes: > > > On Fri, Mar 26, 2021 at 05:28:40PM +0100, Cecil Westerhof via ffmpeg-user > > wrote: > >> Peter White writes: > >> > >> > On Fri, Mar 26, 2021 at 09:55:21AM +0100, Cecil Westerhof via > >> > ffmpeg-user wrote: > >> >> I want to publish a speech I gave during a Zoom meeting. But cutting > >> >> it out does not work. > >> >> > >> >> When I use: > >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 > >> >> -acodec copy -vcodec copy -async 1 speech.mp4 > >> >> > >> >> The video starts just a bit to late. But when I use: > >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 > >> >> -acodec copy -vcodec copy -async 1 speech.mp4 > >> >> > >> > > >> > If you can live with further quality loss in the video, you can > >> > transcode it, i.e. -c:v libx264. > >> > > >> > >> I now use: > >> ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 -to 442 > >> -acodec copy -vcodec libx264 -crf 8 -async 1 speech.mp4 > > > > CRF 8 seems excessive. Try 16 for a start. From various online sources I > > gathered that it is pretty much transparent, as in no noticeable > > difference to the original. My own experience shows the same. > > So crf is useful? (Other post said not.) I am now running it without > crf (and async). When it is finished I will try it with crf 16. I am pretty certain Carl Eugen also meant that CRF 8 is excessive for no visible gain in quality. From the documentation of x264 I remember that an decrement of 1 results in a size increase of the video of roughly 12.5 %, so when you use 8 instead of 16 that is 1.125 to the power of 8 the size of the same video encoded with CRF 16, so roughly 2.5 times the size. And you won't notice the difference. Might even try higher values for CRF. Since I, personally, are very conscious about not losing any quality, I use 16. But even that might be too conservative. Consider it a rough ball park figure to get you started. > >> This takes about 8 minutes instead of a second. But I have to live > >> with that. > > > > You could try to do this in multiple stages, maybe. Only transcode the > > first few seconds up to the next keyframe and then stitch that and the > > copied rest together. In theory this should work, but may be not as easy > > to achieve. Obviously the codecs, frame rates and resolutions need to > > match. I guess codec parameters need to match as well, not sure. The > > question is if it is worth the effort. > > I was thinking about a variant of this. Create a few seconds of the > start and a few seconds of the end until I entered the correct values > and then generate the complete file. Don't worry about the end, because there is no restriction on what kind of frame is allowed there. The encoder will simply stop encoding. > It seems that without crf the video is generated faster. It now only > took five minutes. (But maybe my computer was doing less.) It is a lot > smaller: 41.5 MB instead of 147.8 MB. Have a look at the defaults of the x264 encoder. If memory serves, CRF is 23 by default and you will most certainly notice artifacts, especially since you are transcoding from one lossy format to another, because losses propagate. > Now trying with crf 16. And then comparing the video quality. You will see a difference between not specifying CRF and 16. I am pretty sure about that. ;) Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Sat, Mar 27, 2021 at 05:53:56AM +0100, Cecil Westerhof via ffmpeg-user wrote: > Peter White writes: > > > On Fri, Mar 26, 2021 at 07:02:13PM +0100, Cecil Westerhof via ffmpeg-user > > wrote: > >> Carl Zwanzig writes: > >> > >> > On 3/26/2021 9:28 AM, Cecil Westerhof via ffmpeg-user wrote: > >> >> There is only one problem. The video is 7:21 long, but both mpv and > >> >> vlc think it is 7:30 long. > >> > > >> > IME, the metadata length often lies. When you say it's 7:21, is that > >> > exactly how long it plays for or how long it ought to be? > >> > >> I almost never have this. (If I remember well, only with videos > >> created with ffmpeg. Sometimes it started on a negative timestamp > >> instead of 00:00:00.) > >> > >> Looking at the -to you would expect 7:22, but when I just play it, it > >> ends at 7:21. > > > > You can try using -to as an input option as well. I am not sure, but I > > seem to remember having similar problems once. Also, have a look at -t > > for defining the length of the file as opposed to cutting on time code. > > That is what I did first. Then I got 1:34:19 (or something like it). > So even worse. When you say "first", was that with -vcodec copy? Because that might explain it. Although, I do not know why the file would be so much longer. May be that data stream. BTW, you can use "time codes" for -ss, -to and -t, too. Personally, I do not like having to calculate in seconds when I can simply use the timestamps shown by a player. It is much more intuitive, to me at least, to just say: cut from (-ss) 19:45 -to 27:11 instead of from 1190 to 1631. But that, of course, depends on how you retrieved those timestamps in the first place. I now think, I know why I had problems in the past with -ss as an input and -to as an output option in combination. By using -ss as input option, the output timestamps start at 0, thus -to, in this scenario, is the same as -t, resulting a file of that length. Hence, I suggest to either use both -ss and -to as input or as output options and not mix them as one input and the other as output option. From my understanding the difference between them being used as input or output options, respectively, is that when used as input options they tell the *demuxer* to seek and stop at the given timestamps. Or, more precisely, the demuxer seeks to the last keyframe before the -ss timestamp and the decoder starts decoding from there, discarding all frames before the accurate timestamp. When used as output option that applies to the *decoder*, with "copy" being a special case. Because of this, you might need to wait a long time for the encoding to start, when using them as output options, since the decoder needs to get to the -ss timestamp by decoding frames which get discarded. What I am trying to say is: use -ss and -t(o) as input option whenever you can, unless there is a very good reason--whatever that might be--for using them as output options. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Peter White writes: > On Fri, Mar 26, 2021 at 05:28:40PM +0100, Cecil Westerhof via ffmpeg-user > wrote: >> Peter White writes: >> >> > On Fri, Mar 26, 2021 at 09:55:21AM +0100, Cecil Westerhof via ffmpeg-user >> > wrote: >> >> I want to publish a speech I gave during a Zoom meeting. But cutting >> >> it out does not work. >> >> >> >> When I use: >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 >> >> -acodec copy -vcodec copy -async 1 speech.mp4 >> >> >> >> The video starts just a bit to late. But when I use: >> >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 >> >> -acodec copy -vcodec copy -async 1 speech.mp4 >> >> >> > >> > If you can live with further quality loss in the video, you can >> > transcode it, i.e. -c:v libx264. >> > >> >> I now use: >> ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 -to 442 >> -acodec copy -vcodec libx264 -crf 8 -async 1 speech.mp4 > > CRF 8 seems excessive. Try 16 for a start. From various online sources I > gathered that it is pretty much transparent, as in no noticeable > difference to the original. My own experience shows the same. So crf is useful? (Other post said not.) I am now running it without crf (and async). When it is finished I will try it with crf 16. >> This takes about 8 minutes instead of a second. But I have to live >> with that. > > You could try to do this in multiple stages, maybe. Only transcode the > first few seconds up to the next keyframe and then stitch that and the > copied rest together. In theory this should work, but may be not as easy > to achieve. Obviously the codecs, frame rates and resolutions need to > match. I guess codec parameters need to match as well, not sure. The > question is if it is worth the effort. I was thinking about a variant of this. Create a few seconds of the start and a few seconds of the end until I entered the correct values and then generate the complete file. It seems that without crf the video is generated faster. It now only took five minutes. (But maybe my computer was doing less.) It is a lot smaller: 41.5 MB instead of 147.8 MB. Now trying with crf 16. And then comparing the video quality. -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Carl Eugen Hoyos writes: > Am Fr., 26. März 2021 um 17:28 Uhr schrieb Cecil Westerhof via > ffmpeg-user : > >> ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 >> -to 442 -acodec copy -vcodec libx264 -crf 8 -async 1 speech.mp4 > > The x264 documentation states that there is no good > reason to use "crf 8" and please don't use "acodec copy" > with "async 1", these two options are exclusive. I thought that crf 8 would minimise degrading the video. So that is not true. Long ago I needed that, but probably I did not use acopy there, Thanks. I will change that. -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Peter White writes: > On Fri, Mar 26, 2021 at 07:02:13PM +0100, Cecil Westerhof via ffmpeg-user > wrote: >> Carl Zwanzig writes: >> >> > On 3/26/2021 9:28 AM, Cecil Westerhof via ffmpeg-user wrote: >> >> There is only one problem. The video is 7:21 long, but both mpv and >> >> vlc think it is 7:30 long. >> > >> > IME, the metadata length often lies. When you say it's 7:21, is that >> > exactly how long it plays for or how long it ought to be? >> >> I almost never have this. (If I remember well, only with videos >> created with ffmpeg. Sometimes it started on a negative timestamp >> instead of 00:00:00.) >> >> Looking at the -to you would expect 7:22, but when I just play it, it >> ends at 7:21. > > You can try using -to as an input option as well. I am not sure, but I > seem to remember having similar problems once. Also, have a look at -t > for defining the length of the file as opposed to cutting on time code. That is what I did first. Then I got 1:34:19 (or something like it). So even worse. > Plus, from your original post it looks like there is some additional > "data" stream in there, which might get copied. Sometime ffmpeg needs to > wait for that to finish or an opportune position to stop. Maybe that is > the culprit here. Have a look into the -map option, i.e. -map V -map a > should only give you video and audio but drop everything else. I will look into that. >> >> ffprobe version 4.1.6-1~deb10u1 Copyright (c) 2007-2020 the FFmpeg >> >> developers >> > >> > That's an older version, even though it wouldn't help on this, it's >> > always best to check with as current as you can get. >> >> I am using Debian (stable). That always uses older versions. >> I could look if there is a newer version in backports. > > You can compile it yourself as well. It is not that difficult. Might > need to hunt down some libraries, but that is basically just looking at > the error messages of configure and finding the appropriate packages. > Also, config.log and apt-file can help a great deal. I will look into that also. -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Fri, Mar 26, 2021 at 05:28:40PM +0100, Cecil Westerhof via ffmpeg-user wrote: > Peter White writes: > > > On Fri, Mar 26, 2021 at 09:55:21AM +0100, Cecil Westerhof via ffmpeg-user > > wrote: > >> I want to publish a speech I gave during a Zoom meeting. But cutting > >> it out does not work. > >> > >> When I use: > >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 > >> -acodec copy -vcodec copy -async 1 speech.mp4 > >> > >> The video starts just a bit to late. But when I use: > >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 > >> -acodec copy -vcodec copy -async 1 speech.mp4 > >> > > > > If you can live with further quality loss in the video, you can > > transcode it, i.e. -c:v libx264. > > > > I now use: > ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 -to 442 -acodec > copy -vcodec libx264 -crf 8 -async 1 speech.mp4 CRF 8 seems excessive. Try 16 for a start. From various online sources I gathered that it is pretty much transparent, as in no noticeable difference to the original. My own experience shows the same. > This takes about 8 minutes instead of a second. But I have to live > with that. You could try to do this in multiple stages, maybe. Only transcode the first few seconds up to the next keyframe and then stitch that and the copied rest together. In theory this should work, but may be not as easy to achieve. Obviously the codecs, frame rates and resolutions need to match. I guess codec parameters need to match as well, not sure. The question is if it is worth the effort. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Fri, Mar 26, 2021 at 07:02:13PM +0100, Cecil Westerhof via ffmpeg-user wrote: > Carl Zwanzig writes: > > > On 3/26/2021 9:28 AM, Cecil Westerhof via ffmpeg-user wrote: > >> There is only one problem. The video is 7:21 long, but both mpv and > >> vlc think it is 7:30 long. > > > > IME, the metadata length often lies. When you say it's 7:21, is that > > exactly how long it plays for or how long it ought to be? > > I almost never have this. (If I remember well, only with videos > created with ffmpeg. Sometimes it started on a negative timestamp > instead of 00:00:00.) > > Looking at the -to you would expect 7:22, but when I just play it, it > ends at 7:21. You can try using -to as an input option as well. I am not sure, but I seem to remember having similar problems once. Also, have a look at -t for defining the length of the file as opposed to cutting on time code. Plus, from your original post it looks like there is some additional "data" stream in there, which might get copied. Sometime ffmpeg needs to wait for that to finish or an opportune position to stop. Maybe that is the culprit here. Have a look into the -map option, i.e. -map V -map a should only give you video and audio but drop everything else. > >> ffprobe version 4.1.6-1~deb10u1 Copyright (c) 2007-2020 the FFmpeg > >> developers > > > > That's an older version, even though it wouldn't help on this, it's > > always best to check with as current as you can get. > > I am using Debian (stable). That always uses older versions. > I could look if there is a newer version in backports. You can compile it yourself as well. It is not that difficult. Might need to hunt down some libraries, but that is basically just looking at the error messages of configure and finding the appropriate packages. Also, config.log and apt-file can help a great deal. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Fri, Mar 26, 2021 at 04:40:26PM +0100, Bo Berglund wrote: > On Fri, 26 Mar 2021 10:59:23 +0100, Peter White > wrote: > > >You can use ffprobe to find the keyframe timestamps: > > > >ffprobe -select_streams V:0 -show_frames -skip_frame nokey -show_entries > >frame=best_effort_timestamp_time 2021-03-25ToastmastersClubAvond.mp4 > > > > I tested your command ona typical video file and found thta the output looks > basically like this: > > [FRAME] > best_effort_timestamp_time=3900.00 > [/FRAME] > [FRAME] > best_effort_timestamp_time=3905.00 > [/FRAME] > [FRAME] > best_effort_timestamp_time=3910.00 > [/FRAME] > [FRAME] > best_effort_timestamp_time=3915.00 > [/FRAME] > > It seems like there are "frames" at every 5 seconds. Not to be picky, but there are certainly very many more frames. The distinction is between *keyframes* and everything else called a frame. > So on such videos is it impossible to cut say from time 2603 to 3401 and get a > video of length 798 seconds? Extrapolating from your above example, yes and no. If there is a keyframe every five seconds, there is none at 2603, so you would need to either start at 2600 or 2605. You can, however, make the video 768 seconds long, because the last frame need not be a keyframe. Or you could cut the end short at 3401 seconds, no problem. > What does ffmpeg do? > Does it skip to the closest frame border or does it include both the starting > and ending frame so giving a video time of 805 seconds? It will find the last keyframe prior to the timestamp specified by -ss. See the documentation or try it yourself. > Switching from the copy handler to something else makes ffmpeg work a lot > harder > and processing time goes from 5 seconds to 30 minutes or so That is normal since now your CPU needs to actually encode the frames and not just copy packets. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Am Fr., 26. März 2021 um 17:28 Uhr schrieb Cecil Westerhof via ffmpeg-user : > ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 > -to 442 -acodec copy -vcodec libx264 -crf 8 -async 1 speech.mp4 The x264 documentation states that there is no good reason to use "crf 8" and please don't use "acodec copy" with "async 1", these two options are exclusive. Carl Eugen ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Carl Zwanzig writes: > On 3/26/2021 9:28 AM, Cecil Westerhof via ffmpeg-user wrote: > >> No, that I cannot do. I cannot publish stuff containing other people. > > Well you -can-, may not want to. I used cannot in the sense that I am not allowed to. ;-) >> There is only one problem. The video is 7:21 long, but both mpv and >> vlc think it is 7:30 long. > > IME, the metadata length often lies. When you say it's 7:21, is that > exactly how long it plays for or how long it ought to be? I almost never have this. (If I remember well, only with videos created with ffmpeg. Sometimes it started on a negative timestamp instead of 00:00:00.) Looking at the -to you would expect 7:22, but when I just play it, it ends at 7:21. >> ffprobe version 4.1.6-1~deb10u1 Copyright (c) 2007-2020 the FFmpeg developers > > That's an older version, even though it wouldn't help on this, it's > always best to check with as current as you can get. I am using Debian (stable). That always uses older versions. I could look if there is a newer version in backports. -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On 3/26/2021 9:28 AM, Cecil Westerhof via ffmpeg-user wrote: No, that I cannot do. I cannot publish stuff containing other people. Well you -can-, may not want to. There is only one problem. The video is 7:21 long, but both mpv and vlc think it is 7:30 long. IME, the metadata length often lies. When you say it's 7:21, is that exactly how long it plays for or how long it ought to be? ffprobe version 4.1.6-1~deb10u1 Copyright (c) 2007-2020 the FFmpeg developers That's an older version, even though it wouldn't help on this, it's always best to check with as current as you can get. z! ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Peter White writes: > On Fri, Mar 26, 2021 at 09:55:21AM +0100, Cecil Westerhof via ffmpeg-user > wrote: >> I want to publish a speech I gave during a Zoom meeting. But cutting >> it out does not work. >> >> When I use: >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 >> -acodec copy -vcodec copy -async 1 speech.mp4 >> >> The video starts just a bit to late. But when I use: >> ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 >> -acodec copy -vcodec copy -async 1 speech.mp4 >> >> which is five seconds earlier. I get the same output. >> >> Am I doing something wrong? > > This is the expected outcome, because, due to the nature of lossy video > codecs, one can only start on keyframes. Please have a look at the > description of the -ss option for further details > >> Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, >> 1920x1080, 2070 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default) >> Metadata: >> creation_time : 2021-03-25T19:02:11.00Z >> handler_name: H.264/AVC video >> encoder : AVC Coding > > This is a lossy codec. > > If you can live with further quality loss in the video, you can > transcode it, i.e. -c:v libx264. > > Or you can set the start point some seconds further back. This way you > will not get the perfect cut but at least you do not lose anything of > the content you want. No, that I cannot do. I cannot publish stuff containing other people. I now use: ffmpeg -y -ss 1189 -i 2021-03-25ToastmastersClubAvond.mp4 -to 442 -acodec copy -vcodec libx264 -crf 8 -async 1 speech.mp4 This takes about 8 minutes instead of a second. But I have to live with that. There is only one problem. The video is 7:21 long, but both mpv and vlc think it is 7:30 long. And even ffprobe does think that: ffprobe version 4.1.6-1~deb10u1 Copyright (c) 2007-2020 the FFmpeg developers built with gcc 8 (Debian 8.3.0-6) configuration: --prefix=/usr --extra-version='1~deb10u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared libavutil 56. 22.100 / 56. 22.100 libavcodec 58. 35.100 / 58. 35.100 libavformat58. 20.100 / 58. 20.100 libavdevice58. 5.100 / 58. 5.100 libavfilter 7. 40.101 / 7. 40.101 libavresample 4. 0. 0 / 4. 0. 0 libswscale 5. 3.100 / 5. 3.100 libswresample 3. 3.100 / 3. 3.100 libpostproc55. 3.100 / 55. 3.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'speech.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf58.20.100 Duration: 00:07:30.90, start: 0.00, bitrate: 2750 kb/s Chapter #0:0: start 0.00, end 442.00 Metadata: title : Recording Started Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1024x576, 2765 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default) Metadata: handler_name: H.264/AVC video Stream #0:1(und): Audio: mp3 (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 34 kb/s (default) Metadata: handler_name: AAC audio Stream #0:2(eng): Data: bin_data (text / 0x74786574) Metadata: handler_name: SubtitleHandler Unsupported codec with id 100359 for input stream 2 -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Fri, 26 Mar 2021 10:59:23 +0100, Peter White wrote: >You can use ffprobe to find the keyframe timestamps: > >ffprobe -select_streams V:0 -show_frames -skip_frame nokey -show_entries >frame=best_effort_timestamp_time 2021-03-25ToastmastersClubAvond.mp4 > Interesting, I have wondered about why my ffmpeg cut engine does not give me clean cuts... I tested your command ona typical video file and found thta the output looks basically like this: [FRAME] best_effort_timestamp_time=3900.00 [/FRAME] [FRAME] best_effort_timestamp_time=3905.00 [/FRAME] [FRAME] best_effort_timestamp_time=3910.00 [/FRAME] [FRAME] best_effort_timestamp_time=3915.00 [/FRAME] It seems like there are "frames" at every 5 seconds. So on such videos is it impossible to cut say from time 2603 to 3401 and get a video of length 798 seconds? What does ffmpeg do? Does it skip to the closest frame border or does it include both the starting and ending frame so giving a video time of 805 seconds? Switching from the copy handler to something else makes ffmpeg work a lot harder and processing time goes from 5 seconds to 30 minutes or so -- Bo Berglund Developer in Sweden ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Fri, Mar 26, 2021 at 10:59:23AM +0100, Peter White wrote: > If you can live with further quality loss in the video, you can > transcode it, i.e. -c:v libx264. Forgot one thing. You can, and maybe should, use -ss as an input option. This way ffmpeg does not decode the whole file until it reaches the cut point. It will be an accurate cut if you use a real codec as opposed to the copy codec. Again, see -ss and -accurate_seek for more details. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Fri, Mar 26, 2021 at 09:55:21AM +0100, Cecil Westerhof via ffmpeg-user wrote: > I want to publish a speech I gave during a Zoom meeting. But cutting > it out does not work. > > When I use: > ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 > -acodec copy -vcodec copy -async 1 speech.mp4 > > The video starts just a bit to late. But when I use: > ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 > -acodec copy -vcodec copy -async 1 speech.mp4 > > which is five seconds earlier. I get the same output. > > Am I doing something wrong? This is the expected outcome, because, due to the nature of lossy video codecs, one can only start on keyframes. Please have a look at the description of the -ss option for further details > Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, > 1920x1080, 2070 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default) > Metadata: > creation_time : 2021-03-25T19:02:11.00Z > handler_name: H.264/AVC video > encoder : AVC Coding This is a lossy codec. If you can live with further quality loss in the video, you can transcode it, i.e. -c:v libx264. Or you can set the start point some seconds further back. This way you will not get the perfect cut but at least you do not lose anything of the content you want. You can use ffprobe to find the keyframe timestamps: ffprobe -select_streams V:0 -show_frames -skip_frame nokey -show_entries frame=best_effort_timestamp_time 2021-03-25ToastmastersClubAvond.mp4 Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
On Fri, Mar 26, 2021 at 10:07:14AM +0100, Michael Koch wrote: > Am 26.03.2021 um 09:55 schrieb Cecil Westerhof via ffmpeg-user: > > I want to publish a speech I gave during a Zoom meeting. But cutting > > it out does not work. > > > > When I use: > > ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 > > -acodec copy -vcodec copy -async 1 speech.mp4 > > > > The video starts just a bit to late. But when I use: > > ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 > > -acodec copy -vcodec copy -async 1 speech.mp4 > > > > which is five seconds earlier. I get the same output. > > > > Am I doing something wrong? > > Without re-encoding you can only cut at keyframes. > If you want to cut at exact times, you must remove -acodec copy and -vcodec > copy -acodec copy should be fine. Cheers, Peter ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Cutting out part of a video does not work
Am 26.03.2021 um 09:55 schrieb Cecil Westerhof via ffmpeg-user: I want to publish a speech I gave during a Zoom meeting. But cutting it out does not work. When I use: ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4 The video starts just a bit to late. But when I use: ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4 which is five seconds earlier. I get the same output. Am I doing something wrong? Without re-encoding you can only cut at keyframes. If you want to cut at exact times, you must remove -acodec copy and -vcodec copy Michael ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
[FFmpeg-user] Cutting out part of a video does not work
I want to publish a speech I gave during a Zoom meeting. But cutting it out does not work. When I use: ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4 The video starts just a bit to late. But when I use: ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4 which is five seconds earlier. I get the same output. Am I doing something wrong? Output: ffmpeg version 4.1.6-1~deb10u1 Copyright (c) 2000-2020 the FFmpeg developers built with gcc 8 (Debian 8.3.0-6) configuration: --prefix=/usr --extra-version='1~deb10u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared libavutil 56. 22.100 / 56. 22.100 libavcodec 58. 35.100 / 58. 35.100 libavformat58. 20.100 / 58. 20.100 libavdevice58. 5.100 / 58. 5.100 libavfilter 7. 40.101 / 7. 40.101 libavresample 4. 0. 0 / 4. 0. 0 libswscale 5. 3.100 / 5. 3.100 libswresample 3. 3.100 / 3. 3.100 libpostproc55. 3.100 / 55. 3.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '2021-03-25ToastmastersClubAvond.mp4': Metadata: major_brand : mp42 minor_version : 0 compatible_brands: isommp42 creation_time : 2021-03-25T19:02:11.00Z Duration: 01:34:26.16, start: 0.00, bitrate: 2198 kb/s Chapter #0:0: start 0.00, end 4016.12 Metadata: title : Recording Started Chapter #0:1: start 4016.12, end 4048.20 Metadata: title : Sharing Started Chapter #0:2: start 4048.20, end 5666.16 Metadata: title : Sharing Stopped Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 126 kb/s (default) Metadata: creation_time : 2021-03-25T19:02:11.00Z handler_name: AAC audio Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 2070 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default) Metadata: creation_time : 2021-03-25T19:02:11.00Z handler_name: H.264/AVC video encoder : AVC Coding Stream #0:2(und): Data: bin_data (text / 0x74786574) Metadata: creation_time : 2021-03-25T19:02:11.00Z handler_name: Text Output #0, mp4, to 'speech.mp4': Metadata: major_brand : mp42 minor_version : 0 compatible_brands: isommp42 encoder : Lavf58.20.100 Chapter #0:0: start 0.00, end 446.00 Metadata: title : Recording Started Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, q=2-31, 2070 kb/s, 25 fps, 25 tbr, 30k tbn, 30k tbc (default) Metadata: creation_time : 2021-03-25T19:02:11.00Z handler_name: H.264/AVC video encoder : AVC Coding Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 126 kb/s (default) Metadata: creation_time : 2021-03-25T19:02:11.00Z handler_name: AAC audio Stream mapping: Stream #0:1 -> #0:0 (copy) Stream #0:0 -> #0:1 (copy) Press [q] to stop, [?] for help frame=0 fps=0.0 q=-1.0 size= 0kB time=00:00:00.00 bitrate=N/A speed= 0x.frame= 2057 fps=2057 q=-1.0 size= 39168kB time=00:01:27.80 bitrate=3654.5kbits/s speed=87.8x.frame= 7885 fps=5256 q=-1.0 size= 154112kB time=00:05:21.27 bitrate=3929.6kbits/s speed= 214x.frame=11017 fps=5760 q=-1.0 Lsize= 232009kB time=00:07:25.97 bitrate=4261.7kbits/s speed= 233x video:224885kB audio:6873kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.107917% -- Cecil Westerhof Senior Software Engineer LinkedIn: http://www.linkedin.com/in/cecilwesterhof ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org
