Michael Niedermayer <[email protected]> added the comment: [...] > > > COMMAND LINE 1 RESULTS > > > ---------------------- > > > No "impossible bitrate constraints, this will > fail" > > > warning > > > Buffer underflow > > > > > Video Peak 9845 Average 8398 > > > > What tool was used to find these 2 values? > > "MPEG Bitrate Viewer" (bitrate.exe) 1.5.054
Considering that google shows zero hits for "mpeg bitrate viewer" "video buffer verifier" I have no faith that this tool implements a VBV, and if it does not, its output would be wild guesses and meaningless [...] > > > > > > WHAT WE KNOW SO FAR > > > ------------------- > > > > > > a) Buffer underflows seem to occur more severely > with "high > > quality" > > > encodes that involve e.g. -mbd 2 - trellis. Both > average and peak > > > bitrate are also higher. > > > > > b) Hervé found that reducing -buf_size avoids > excessive > > bitrate, but > > > at the expense of DVD-Video compliance of course. > It's > > unclear whether > > > this was in the presence of the -maxrate option. > > > > what i know is that you guys dont know too much. > > That is quite correct in my case :-). > > > a increase in bufsize breaks compliance, a decrease > does not > > normally also iam not convinced that there is any > bug in > > libav* at all at least you have not provided a non > > contradictionary case that produced any issues > > > > [...] > > > CLOSE > > > ----- > > > > > > I am under lots of pressure to finish my current > DVD magnum > > opus soon, > > > and if there's any prospect of investigating and > hopefully > > fixing this > > > bug in the near future, please let me know where I > can help with > > > testing and/or more information. > > > > given that you managed to feed ffmpeg with > contradictionary > > parameters the buffer underflows you report are just > a case > > of garbage in, garbage out. > > > > If you can provide a minimal command line with non > > contradictionary paremeters (you need a gap between > muxrate > > and the sum of all video and audio max rates), how > large that > > gap has to be, i dont know but not 0, and also not > 0.1%, > > mpeg-ps is a mildly bloated format it does need some > space > > for its bloat! > > Yes. > > The very compelling evidence is on my hard drive. It > involves an encode with more real-world bitrates: > > ffmpeg -i "Movie.avi.37.avs" -target pal-dvd -muxrate > 10080000 -acodec ac3 -ab 128000 -flags ildct+ilme -g > 15 -vcodec mpeg2video -b 6300000 -pass > 1 "Movie.avi.37.mpg" > ffmpeg -i "Movie.avi.37.avs" -target pal-dvd -muxrate > 10080000 -acodec ac3 -ab 128000 -flags ildct+ilme -g > 15 -vcodec mpeg2video -b 6300000 -pass > 2 "Movie.avi.37.mpg" > > That encode works. > > When I add -maxrate 9800000, the average and peak > video bitrates shoot up and (on pass 2) buffer > underflows result. > > Much more believable evidence? ;-) nope, 10080k - 128k - 9800k = 152k 152k / 10080k = ~ 0.015 that is 1.5% 1.5% might simply not be enough for mpeg-ps overhead [...] > 2) You and I need to find a way to get that 36GB file > to you. Then everybody would be perfectly happy, but I > have neither fast nor much bandwidth! If you have any > suggestions, please let me know. I dont need the file, though if you ever want to send someone large amounts of data, a bunch of DVD-R/CD-R/SD cards/usb sticks (whatever is cheapest) per snailmail is the way to go. > > LATEST SVN > ---------- > Because I am finding FFmpeg useful, as a token of > gratitude I am trying to contribute to the greater > effort what I can. What I can contribute is helping to > idenfity and correct code and documentation errors. My > programming has become too rusty for anything else. That is a pitty, if you did code as much as you write english text you would surely be a pretty valuable developer. also id like to repeat that the target dvd option enables a maxrate and that your adding of a maxrate command line option really is just changing its value not adding a limit where none was before. [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB The educated differ from the uneducated as much as the living from the dead. -- Aristotle ---------- status: open -> closed substatus: needs_more_info -> invalid _____________________________________________________ FFmpeg issue tracker <[email protected]> <https://roundup.ffmpeg.org/roundup/ffmpeg/issue1081> _____________________________________________________
