AVI's AV not in sync (sometimes)

[zehd]

Was just wondering if I could do anything about AV not being in sync when playing avi files through the MVP. It happens at random, mostly it plays fine , sometimes it's not. Same file, different file doesn't matter. I use the same encoding settings on all AVI's so no diffrences between files.
Anyone any thoughts ?

While writing and troubleshooting ZProcess for both FFmpeg and MEncoder, I discovered that FFmpeg seems to do a better job of keeping things in sync.

I also noticed that a fresh reboot of the MVP seems to fix a sync issue, though I can't see why...

Also, the settings for FFmpeg that worked the best also required the most beefy CPU. 720x480, 6000 Vid Bitrate, 224 Aud Bitrate, 48000 Aud Freq.

Then there were some vids that just wouldn't keep in sync. Oh well

[SuMo]

Also, the settings for FFmpeg that worked the best also required the most beefy CPU. 720x480, 6000 Vid Bitrate, 224 Aud Bitrate, 48000 Aud Freq.
Then there were some vids that just wouldn't keep in sync. Oh well

Just wondering, any difference between files that will stay sync and the ones that won't (size, bitrate, ac3/mp3 audio, freq ?)

I'll download and try your latest ZProcess, keep you posted.

=======================================

The family had a go at the MVP with the new settings and till now I didn't notice any sync issues.
Although AVI's have to be transcoded on the fly maybe if no resizing has to be done, and audio bitrate is the same in the ffmpeg cmd line as the AVI file, the chance to sync problems is minimized.

[zehd]

Just wondering, any difference between files that will stay sync and the ones that won't (size, bitrate, ac3/mp3 audio, freq ?)

I don't see any difference in the files that work and the ones that don't

[SuMo]

I don't see any difference in the files that work and the ones that don't

Hmmm, my argues down the drain......

[zehd]

Just playing with VLC as a transcoder in ZProcess... It's keeping everything in sync and even faster then MEncoder.

Keep watching for a release....

[4zm4r3d02]

I also noticed that a fresh reboot of the MVP seems to fix a sync issue, though I can't see why...

I believe that at least part of the sync problem has to do with the hardware/firmware of the mvp. I often get a/v sync problems when I fast-forward, and I only use the mvp for viewing mpeg videos, so it can't be a transcoder issue in my case.

There was one version of the dongle.bin that seemed to cure this, but I quit using it because of the annoying, large information display that stayed on-screen much too long.

[kennyd]

Hi,

My MVP Av and playback video goes out of sync also. It seems to happen when I forward a few minutes. By forwarding and rewinding sometimes it corrects itself. Any ideas?

Thanks
Kenny

[zehd]

Hi,

My MVP Av and playback video goes out of sync also. It seems to happen when I forward a few minutes. By forwarding and rewinding sometimes it corrects itself. Any ideas?

Thanks
Kenny

That is the problem many of us have. There is no black and white fix for it.

re: MEncoder/FFmpeg/VLC/ZProcess
I have also noticed that transcoding AVI to MPEG with either MEncoder, FFmpeg, or VLC seems better at keeping sync on a faster machine. FFmpeg is the hands down winner IMHO.

It seems (for me at least) no amount of tweaking can outdo a faster computer.

That said, even a really fast computer has sync issues... as mentioned in other posts, the resulting MPG after transcode is lacking some sync track or something that is created properly when recording on the PVR straight to MPG... Something is getting lost in the translation and there aren't many transcoders out there that can fix that...

[SuMo]

... as mentioned in other posts, the resulting MPG after transcode is lacking some sync track or something that is created properly when recording on the PVR straight to MPG...

zehd, how about using enough keyframes (about every 24 frames) the sync issue should be minimized .... unfortunately will never disappear.

[zehd]

zehd, how about using enough keyframes (about every 24 frames) the sync issue should be minimized .... unfortunately will never disappear.

I've been playing with key frames, actually referred to as keyint with MEncoder. The option to play with the number is built into ZProcess. I haven't noticed any appreciable difference even cranking down the value to 1 or 12...

There's seems to be some confusion as to the allowed values...

14.8.1.2. GOP Size Constraints

DVD, VCD, and SVCD also constrain you to relatively low GOP (Group of Pictures) sizes. For 30 fps material the largest allowed GOP size is 18. For 25 or 24 fps, the maximum is 15. The GOP size is set using the keyint option.

This came out of a how to: http://www.cscs.ch/~mvalle/mencoder/mencoder.html

opt="vbitrate=2160000:mbd=2:keyint=132:vqblur=1.0:cmp=2ubcmp=2:dia=2:mv0:last_pred=3"

http://gentoo-wiki.com/HOWTO_mencoder_divx_to_dvd

keyint=<gop>: sets the maximum interval between keyframes in frames (15 for PAL DVD, 18 for NTSC DVD)