> Excerpts from pshirkey's message of 2011-06-10 21:56:06 +0200: >> > Excerpts from Ralf Mardorf's message of 2011-06-10 19:24:54 +0200: >> >> On Fri, 2011-06-10 at 18:57 +0200, Renato wrote: >> >> > On Fri, 10 Jun 2011 17:58:46 +0200 >> >> > Philipp <hollunder@xxxxxxxxxxx> wrote: >> >> > >> >> > > Hi, >> >> > > sorry for abusing this list for a mostly video editing question, >> but >> >> I >> >> > > didn't find a proper list and knew that we have some video people >> on >> >> > > this list. >> >> > > >> >> > > I'd like to fix some videos that have partially out of sync video >> >> and >> >> > > audio, meaning that beginning at a certain point in the video the >> >> > > audio is suddenly out of sync by a couple of seconds. There's no >> >> > > constant change, the delay seems fixed once it's there. >> >> > > >> >> > > I wonder how to fix such a thing. The files are xvid encoded >> videos >> >> > > and vbr mp3 audio inside avi containers. I thought it should be >> >> > > reasonably easy to cut and move the audio (re-encode if >> unavoidable, >> >> > > but I know it's in principle possible without) and put it back in >> a >> >> > > container, but I didn't manage. >> >> > > >> >> > > Can someone recommend a program/workflow that would allow this? >> >> > > >> >> > > I tried: >> >> > > - Avidemux: seems like actual editing is not what this program >> was >> >> > > written for, couldn't figure it out, but it seems close >> >> > > >> >> > > - openshot: couldn't figure out how to separate video/audio >> >> > > >> >> > > - kino: seems to only work with DV-files, apparently takes ages >> to >> >> > > decode the file, doesn't seem to be what I need >> >> > > >> >> > > - openmovieeditor: I figured it might work by dragging the file >> to >> >> > > both a video and an audio track, but I got extremely garbled >> audio >> >> > > output, no idea what's wrong >> >> > > >> >> > > - cinelerra-cv: Doesn't start. No error message, it simply shows >> no >> >> > > window, nothing. Well, it does something with the screen, but >> it >> >> > > shows nothing. >> >> > > >> >> > > - pitivi: Doesn't seem like it can play back the video. I can >> drag >> >> the >> >> > > video to the tracks and it starts to draw a waveform, I guess >> no >> >> > > video thumbnails because of: gst.ElementNotFoundError: pngenc >> >> > > Doesn't seem to be able to play the video. >> >> > > >> >> > > - kdenlive: would require me to install 30 additional packages, >> >> total >> >> > > about 200MB, no thanks. >> >> > > >> >> > > I thought it would be a simple task, really nothing fancy. Seems >> >> like >> >> > > I was wrong. >> >> > > >> >> > > Regards, >> >> > > Philipp >> >> > > >> >> > >> >> > Hi, unfortunately can't give you a full solution, but only a hint: >> in >> >> > mplayer with "-" and "+" you can adjust audio/video syncronization >> by >> >> > multiples of 100ms (maybe you cand do finer, but I'm not sure). >> >> > >> >> > maybe you could then somehow record the output to a new file? >> > >> > Thanks Renato, I've played with that already and know the approximate >> > offsets, but that doesn't help much. I'm not sure screen recorders >> > typically can pause and resume, and even then it would be less than >> > optimal anyway due to the transcoding of both audio and video. >> > >> > Also, to clarify, those offsets are constant but only appear beginning >> > at a certain point in the file, imaginary example: after 97 Minutes >> the >> > offset is suddenly approximately -9600ms. Hence shifting the offset of >> > the whole file doesn't help. >> > >> >> >> I went through this a couple of years back with pretty much the same >> result. The general consensus round here was that it is not possible to >> shrink a video to fit with an audio track. Instead you should stretch >> the >> audio track to fit the video. >> >> I ended up using Blender to edit the video into chunks and align chunks >> of >> audio to fit as best as possible. >> >> I don't understand why it is not possible to resize a video track. It >> seems to me that dropping video frames is significantly easier >> programatically than time stretching audio. > > I've only done this with one video so far, so I don't know whether it > works fine in general, but in this case mencoder dropped a couple of > seconds that were just black anyway, so no real loss. It was a fade out > to black and I jugged down the time the moment it was black. I somewhat > wonder how it was messed up, I suspect files were put together and some > black frames were added without caring for audio, or something like > that. Anyways, there's no loss of content with this file, which was with > almost ten seconds delay by far the worst of the bunch. Ok, according to > mplayer the file is now 13 seconds shorter instead of 9.55, but who > cares as long as the result is fine. > > So it seems mencoder can just drop video frames. That's good to know. For references sake, what was the commandline that you ended up using? > I was also surprised about the speed. I guess it took at most a minute > per operation on this old cheap laptop and ~3h video, most likely it > avoided re-encoding of anything, which is a good thing in my book. In > contrast, just loading the video into kino would probably have taken an > hour. > > Regards, > Philipp > > _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
