Re: [FFmpeg-user] Understanding the behavior of "-ss/-t" option

[Gyan]

On Fri, Sep 8, 2017 at 10:38 AM, Nitish Prabhu 
wrote:

>
> Does FFmpeg apply the option "-ss/-t" based on container time stamp
> information, or is it based on bit stream timing information?
>

Thus, I wanted to understand how seeking works under the hood in FFmpeg.
>

You'll want to use the seek_timestamp option.

As it says in the docs,

"-seek_timestamp (*input*)

This option enables or disables seeking by timestamp in input files with
the -ss option. It is disabled by default. If enabled, the argument to the
-ss option is considered an actual timestamp, and is not offset by the
start time of the file. This matters only for files which do not start from
timestamp 0, such as transport streams."
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[FFmpeg-user] Understanding the behavior of "-ss/-t" option

[Nitish Prabhu]

Hi,

Does FFmpeg apply the option "-ss/-t" based on container time stamp
information, or is it based on bit stream timing information?

I generated a stream with a 60 second start offset using the following command:
$ ffmpeg -itsoffset 60 -i input_clip_x264.mp4 -c copy input_clip_x264_offset.mp4

I tried to seek to a particular time in the generated stream using the
following:
$ ffmpeg -ss 60 -t 10 -i input_clip_x264_offset.mp4 -copyts -filter:v
"select=between(t\,60.000\,70.000)" -c:v libx264 offset_extract.mp4

I see that no frames are extracted in the above command. Using
ffprobe, I checked that the frame timestamps start from 60 in the clip
with offset (input_clip_x264_offset.mp4). So, in theory, this had to
work. If I run the above command with "-ss 0", I see that it is able
to extract frames.

Thus, I wanted to understand how seeking works under the hood in FFmpeg.

Thanks!

Best Regards,
Nitish
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Re: [FFmpeg-user] Dolby E decoder

[Carl Eugen Hoyos]

2017-09-07 18:20 GMT+02:00 Frédéric Busnel-Joncour :

>> And one last question, is it possible to wrap Dolby-E stream in mov
>> or mxf container using ffmpeg without altering it in any way ?

Do you have a mov and / or mxf file containing Dolby-E so we
better understand what you request?

(Sorry, my knowledge of SMPTE 337M is limited but I know that so far,
this is the only "format" for which FFmpeg supports Dolby-E, and that
adding support for other formats will be possible but hasn't been
done yet.)

Carl Eugen
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Re: [FFmpeg-user] mp4 files size problem

[James Girotti]

On Thu, Sep 7, 2017 at 9:52 AM, Daniel <5960...@gmail.com> wrote:

> Thank you for the reply . I think you are right about the hardware encoder
> . I have encoded the video with libx264 and the output file was 189MB. Do
> you know what is the difference between nvenc_h264 and h264_nvenc  encoders
> ?


From what I can tell from the source code "nvenc_h264" is an alias for
"h264_nvenc", but "nvenc_h264" is the old deprecated name. So you if you're
writing any scripts/programs you should use "h264_nvenc"
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Re: [FFmpeg-user] mp4 files size problem

[Daniel]

Thank you for the reply . I think you are right about the hardware 
encoder . I have encoded the video with libx264 and the output file was 
189MB. Do you know what is the difference between nvenc_h264 and 
h264_nvenc  encoders ?



On 7.09.2017 17:09, Cley Faye wrote:

2017-09-07 15:57 GMT+02:00 Daniel <5960...@gmail.com>:


Hello Everyone,

I have tried to convert some videos to mp4 format what has surprised me
was the size of the videos, After the conversion some videos were 2,3,4
times bigger then the original wmv files. Here is the command i used to
convert :  /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v
nvenc_h264  video500.mp4 ; After this command the mp4 file is 630MB  and
the wmv file is 150MB (you can find attached the ffprobe to bothe files).
If you can suggest any way on how to keep the quality and make the mp4
files smaller please let me know .


ps: On some mp4 videos the bitrate has doubled have no idea why ?


​If you don't supply your own settings, ffmpeg (and/or the underlying
codec) will assume some default values, not necessarily in compliance with
the input. In your case, you probably want (at least) to set the bitrate.
Also, I think that hardware encoder tend to produce bigger file for same
quality (and worse quality for same size), but this might not be accurate
anymore.​
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Re: [FFmpeg-user] Playing a file with subtitles that have single quotes in their filename

[Gonzalo Garramuño]

Never mind me.  I figured it out by myself.   Here's the quoted line:

$ ffplay 
/media/gga/Datos/movies/trailers/big_buck_bunny_1080p_surround.avi -vf 
subtitles=/media/gga/Datos/code/applications/mrViewer/Charlie\\\'s\ 
Angels.srt:charenc=ISO-8859-1



El 06/09/17 a las 21:36, Gonzalo Garramuño escribió:



El 06/09/17 a las 19:19, Gonzalo Garramuño escribió:

I found the web page 
https://ffmpeg.org/ffmpeg-utils.html#Quoting-and-escaping

and according to that and ffescape, I should be using:

Charlie\'s Angels.srt

Trying:
 ffplay 
/media/gga/Datos/movies/trailers/big_buck_bunny_1080p_surround.avi -vf 
subtitles=../../Charlie\\\'s\\\ Angels.srt


Gets me a tad further:

[Parsed_subtitles_0 @ 0x7fc591925420] Unable to open ../../Charlies 
Angels.srt
Error initializing filter 'subtitles' with args '../../Charlie's 
Angels.srt'


Reports the file name is being passed correctly, but the subtitle 
parser messes it up.

Is there any workaround against this dilemma?


--
Gonzalo Garramuño

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Re: [FFmpeg-user] Dolby E decoder

[Frédéric Busnel-Joncour]

> Afaict, SMPTE 337M is a file format.

OK, thanks. I have made many search but can't find any info about it. With what 
I've found, it seems to be more like a protocol (non-PCM stream transport in an 
AES-3 link) than a file format ?

> Please do not top-post here, Carl Eugen

Sorry, I don't understand what you mean ? What should I do to avoid that ?


And What about this question :

> And one last question, is it possible to wrap Dolby-E stream in mov or mxf 
> container using ffmpeg without altering it in any way ?


Best,

Fred


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Re: [FFmpeg-user] mp4 files size problem

[Carl Eugen Hoyos]

2017-09-07 15:57 GMT+02:00 Daniel <5960...@gmail.com>:

> I have tried to convert some videos to mp4 format what has surprised me was
> the size of the videos, After the conversion some videos were 2,3,4 times
> bigger then the original wmv files. Here is the command i used to convert :
> /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v nvenc_h264
> video500.mp4

Complete, uncut console output missing.

You did not specify a bitrate, so I assume you did not care about the
size of the output file, is that wrong?

What is the resulting file size if you encode with libx264?

Carl Eugen
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Re: [FFmpeg-user] mp4 files size problem

[Cley Faye]

2017-09-07 15:57 GMT+02:00 Daniel <5960...@gmail.com>:

> Hello Everyone,
>
> I have tried to convert some videos to mp4 format what has surprised me
> was the size of the videos, After the conversion some videos were 2,3,4
> times bigger then the original wmv files. Here is the command i used to
> convert :  /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v
> nvenc_h264  video500.mp4 ; After this command the mp4 file is 630MB  and
> the wmv file is 150MB (you can find attached the ffprobe to bothe files).
> If you can suggest any way on how to keep the quality and make the mp4
> files smaller please let me know .
>
>
> ps: On some mp4 videos the bitrate has doubled have no idea why ?
>

​If you don't supply your own settings, ffmpeg (and/or the underlying
codec) will assume some default values, not necessarily in compliance with
the input. In your case, you probably want (at least) to set the bitrate.
Also, I think that hardware encoder tend to produce bigger file for same
quality (and worse quality for same size), but this might not be accurate
anymore.​
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[FFmpeg-user] mp4 files size problem

[Daniel]

Hello Everyone,

I have tried to convert some videos to mp4 format what has surprised me 
was the size of the videos, After the conversion some videos were 2,3,4 
times bigger then the original wmv files. Here is the command i used to 
convert :  /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v 
nvenc_h264  video500.mp4 ; After this command the mp4 file is 630MB  and 
the wmv file is 150MB (you can find attached the ffprobe to bothe 
files). If you can suggest any way on how to keep the quality and make 
the mp4 files smaller please let me know .



ps: On some mp4 videos the bitrate has doubled have no idea why ?


BR

 ffprobe video500.mp4 
 *
ffprobe version 3.3.3 Copyright (c) 2007-2017 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
  configuration: --enable-gpl --enable-libass --enable-libfdk-aac 
--enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora 
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 
--enable-nonfree --enable-cuda --enable-cuvid --enable-nvenc --bindir=/usr/bin
  libavutil  55. 58.100 / 55. 58.100
  libavcodec 57. 89.100 / 57. 89.100
  libavformat57. 71.100 / 57. 71.100
  libavdevice57.  6.100 / 57.  6.100
  libavfilter 6. 82.100 /  6. 82.100
  libswscale  4.  6.100 /  4.  6.100
  libswresample   2.  7.100 /  2.  7.100
  libpostproc54.  5.100 / 54.  5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video500.mp4':
  Metadata:
major_brand : isom
minor_version   : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf57.71.100
  Duration: 00:41:26.32, start: 0.00, bitrate: 2122 kb/s
Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 480x360 
[SAR 1:1 DAR 4:3], 1987 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
Metadata:
  handler_name: VideoHandler
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, 
fltp, 128 kb/s (default)
Metadata:
  handler_name: SoundHandler


ffprobe video500.wmv 
***
ffprobe version 3.3.3 Copyright (c) 2007-2017 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
  configuration: --enable-gpl --enable-libass --enable-libfdk-aac 
--enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora 
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 
--enable-nonfree --enable-cuda --enable-cuvid --enable-nvenc --bindir=/usr/bin
  libavutil  55. 58.100 / 55. 58.100
  libavcodec 57. 89.100 / 57. 89.100
  libavformat57. 71.100 / 57. 71.100
  libavdevice57.  6.100 / 57.  6.100
  libavfilter 6. 82.100 /  6. 82.100
  libswscale  4.  6.100 /  4.  6.100
  libswresample   2.  7.100 /  2.  7.100
  libpostproc54.  5.100 / 54.  5.100
Input #0, asf, from 'video500.wmv':
  Metadata:
VBR Peak: 1389000
DeviceConformanceTemplate: MP@ML
WM/WMADRCPeakReference: 32767
WM/WMADRCAverageReference: 4467
WMFSDKVersion   : 9.00.00.3267
WMFSDKNeeded: 0.0.0.
IsVBR   : 1
Buffer Average  : 112323
  Duration: 00:41:20.17, start: 0.00, bitrate: 504 kb/s
Stream #0:0(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 2 channels, 
fltp, 48 kb/s
Stream #0:1(eng): Video: wmv3 (Main) (WMV3 / 0x33564D57), yuv420p, 480x360, 
443 kb/s, 29.97 tbr, 1k tbn, 1k tbc
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Re: [FFmpeg-user] Dolby E decoder

[Carl Eugen Hoyos]

2017-09-07 15:38 GMT+02:00 Frédéric Busnel-Joncour :

> Not sure to have well understood: can a SMPTE 337M file be in a wav 
> container, or it has a specific wrap and file extension ?

Afaict, SMPTE 337M is a file format.

Please do not top-post here, Carl Eugen
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Re: [FFmpeg-user] Dolby E decoder

[Frédéric Busnel-Joncour]

Hi Carl Eugen,


Thanks for this quick reply !
Not sure to have well understood: can a SMPTE 337M file be in a wav container, 
or it has a specific wrap and file extension ?


Best regards,

Fred

> 2017-09-07 15:20 GMT+02:00 Frédéric Busnel-Joncour :
> 
>> I've seen that a Dolby E decoder has been added to the last release of 
>> libavcodec.
> 
> So far, only SMPTE 337M files are supported, patch for more file types 
> welcome!
> 
> Carl Eugen
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Re: [FFmpeg-user] Dolby E decoder

[Carl Eugen Hoyos]

2017-09-07 15:20 GMT+02:00 Frédéric Busnel-Joncour :

> I've seen that a Dolby E decoder has been added to the last release of 
> libavcodec.

So far, only SMPTE 337M files are supported, patch for more file types welcome!

Carl Eugen
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[FFmpeg-user] Dolby E decoder

[Frédéric Busnel-Joncour]

Hi there,


First question here !
I've seen that a Dolby E decoder has been added to the last release of 
libavcodec.

I'm sometimes delivered of stereo 24bit/48Khz wav file that are Dolby E encoded 
streams.
Is there a way to tell ffplay to play it as Dolby E and decode it ? By default 
it plays it as a standard PCM wav files.

Sometimes, Dolby E streams are also wrapped into video files, and most of times 
splitted into two mono audio streams. Is there a way, without any rewrap, to 
play and decode it through ffplay ? (select both streams > "merge" as a Dolby E 
stream > decode)

And one last question, is it possible to wrap Dolby-E stream in mov or mxf 
container using ffmpeg without altering it in any way ?


Best regards,

Fred
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Re: [FFmpeg-user] ffprobe reliability

[Carl Eugen Hoyos]

2017-09-05 19:52 GMT+02:00 Vaidas Kascėnas :

> Does anyone have any ideas how I could improve that?

You could use ffmpeg -i with a large probesize (and / or analyzeduration)

Carl Eugen
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