Sound ONLY with "passthrough"

[mk84]

I have a big problem with ffmpegx:

It´s impossible to convert my mpeg-2 files (from eyetv) into other files, this is possible only with the "passthrough" option because with this option i´ve a video with pictures AND sound. With all the other video options there´s only a video without any audio.... I´ve tried nearly all options, also in the Audio Menu, but it seems that there´s something wrong....

The "passthrough" option was very fine for a lot of my recorded files, but now i´ve recorded some music-videos from TV and in this videos you can see the problem very well: Audio and Video are NOT synchron (after converting with "passthrough"), so you can see the artist begins to sing the song and the audio comes with a gap of +/- 2 seconds

So what´s wrong with my ffmpegx? I´ve OS X 10.5.1 but under "Tiger" it works the same way, so that´s not the problem, i think. It´s very important for me to convert my mpeg-2 files from eyetv into a file that works with Quicktime, cause i want to watch them in FrontRow and without other videoplayers and i can cut them with QT (pro), too. But i´m not willing to buy the QT mpeg-2 plugin that costs here 20 euros (nearly 30 US $) !

In my local macuser-forum i couldn´t get working solutions for this problem, so i post it here.....Thanks a lot for all suggestions !!!!

Michael

[tomlee59]

Can you post the logfile output? That might help point the way toward a solution. The information you've provided is not quite enough to go on.

Also, when you drag your eyetv file onto ffmpegx's source window, what does it say about the audio stream? Does it say "unrecognized," or does it in fact identify it? If the latter, what does it say its codec type, bitrate, etc are?

In the absence of that information, here is something to try:

Demux your eyetv file. Then remux it using ffmpegx's muxing tool, for example. Sometimes, vidcap boxes will use a not-quite compliant format that can trip up subsequent processing. Demuxing and remuxing can frequently fix those problems. Once remuxed, try converting the new file and see what happens.

Now, as far as the sync problem is concerned, is the drift rate constant, or is it a fixed offset, or does it jump? The first two can be fixed with relative ease, whereas the latter is a pain. A fixed offset is readily repaired by using ffmpegx's own muxing offset parameter. A constant bitrate can be fixed by processing the audio with a tool like Audacity, which allows you to shorten or elongate the audio track as necessary. It can do this without altering any pitches.

Jumps are tougher. You have to divide up your clip into multiple regions in which the sync is either offset by a constant amount or drifts at a constant rate. Then you fix each segment separately, then recombine the fixed segments. Depending on the number of jumps, this can be a very cumbersome process.

[mk84]

Hello again, this shows ffmpegx about my mpeg2-file (that i´ve picked out of the eyetv-file):

Mpeg 2 Transport Stream [1 program]
Program N∞ 1 contains 2 Elementary Streams:
Stream 1: MPEG 1 audio [pid: 35]
Stream 2: MPEG 2 video [pid: 34]

ffmpegx says in the audio-field: mp2, 48000hz, 384 kbps
video-field: mpeg-2, 720x576, 8000 kbps, 25 fps

That´s my beginning situation. Than i choose "passthrough", now i´ve tried "DivX 3 [.AVI] (ffmepg)"....Ok, there i also have a video with pictures AND audio, but the gap between picture and audio is also +/- 3 seconds, more than with the "passthrough" option.....

ffmpegx shows in this case on the "to AVI" Side:

video-field: ffmpeg msmpeg4, 640x352, 1265 kbps, 25 fps, no crop
audio-field: mp3, 48000 Hz, 128 kbps

I don´t have select or deselct options or changed any settings, i´m a real newbie....

[mk84]

Servus again, currently i´ve made an very interesting notice:

At the beginning of my converted file, the pictures and audio is very synchron.....i would say almost 100 %.

But than with the time (this recorded file takes 4 hours) it drifts away, but only in the converted ffmpegx-file, not in the original eyetv-file !!

I´ve just watched a music-video, that was at the beginning......in this "video-night" this video comes again nearly at the end of the recording.....and than you can see difference very clear.....strange

[tomlee59]

I'm not sure what you're saying in your most recent posts. Are you saying that the original source file has sync problems?

In any case, try selecting "invert mapping" in the audio tab. Ffmpegx expects the video stream to come before the audio one; yours seems to be the other way. Clicking "invert mapping" takes care of that. Perhaps this is the source of your missing audio (but I'm far from certain on this point). At least it's easy to try. Do this experiment on a short clip, of course.

[mk84]

In the source file from eyetv, everthing is 100 % synchron when i watch it with the eyetv software.

Only in the files that i´ve converted so far in ffmpegx (by selecting "passthrough, ffmpeg" or "DivX 3, ffmpeg") there are these gaps between picture and audio, with more length of the video you notice these gaps more and more.....in my above described video the gap is at the end 3 seconds !

I have to select "passthrough" or, as i just noticed, "DivX3", because in all other options i have in the converted file only a picture and no sound at all. But it´s ok if it works with this options, now there´s only the problem that audio and picture is not synchron more and more with the length of the video....

So i will try your suggestions, hope it works and say "thank you!" so far to California!

[tomlee59]

An additional consideration is to keep the target frame rate equal to the source frame rate (in this case, 25fps). I am not sure what ffmpegx chooses as a default, so you may wish to verify what it is doing, and make alterations if necessary.

Good luck!

--Tschüss