Sound out of sync, please help

[Meg]

Hi,
I'm using the divx low motion as a video codec and mp3 compression as my audio codec but when I play the finished product it is out of sync about 10 mins into the movie. How do I fix this ? Please help me.

[UncasMS]

ok, so you see your doctor and tell him:

doc, i'm not feeling fine. help me!



what do you think he will do?

what do you expect someone here to do?

spending time asking you questions, on what exactly you DID to encode?

no, sorry

state ALL facts one should know.
tools, versions, settings etc.

[klettke]

OK.
I'm not the original poster; but I'm having the same problem. I made a two hour movie. Did a DV capture using Pinnacle Studio 7. Used a custom capture mode 352 x 240 at 29.97fps. Resulting total, of course, is over 4GB (Win98SE OS), so I split the avi capture into 3--1.64GB, 2.92GB, 1.47GB. Did an append AVI with Virtual Dub 1.4d. Extracted the audio as a .wav. Used RazorLame (1.1.4) to prepare the mp3. Added a WAV Header with WaveMP3 (1.2). mp3 audio and avi video match precisely in total timings. Return to VirtualDub. Open video file ->desired avi. Audio...WAV Audio-> desired WAV'ed mp3. Options...Sync to audio. Audio...Direct stream copy. Audio...Enable audio/video interleaving. Interleave audio every 500 ms. Video...Filters...Smart Resize. Enabled Size Calculator with a Fit Width of 544, upsize conversion with Precise Bicubic, and Fit width to multiple of 32. Video...Compression...DivX Low-Motion (still using the 3.11 codecs). Keyframe every 6 seconds. Smoothness 86. Data Rate 720 aiming for file size between 650 and 700MB output. Save as .avi... and the file is made. Starts out fine; but de-synchs more and more as movie plays (WMP 6.4). By the end of the 2 hours, it's made it to about 1.75 seconds difference. Appears the same whether it's playing off a 7200 rpm hard disk or burned onto CD-R and played from a 40x CD-ROM player. Converting to Real Media or Windows Media does not result in the same de-sync. Have not tried VideoCD formatting, as goal was single CD; but may try it in the future just for experimentation. Now, the Real Media, Windows Media and VideoCD of course I can do right out of Pinnacle. Haven't attempted doing a custom Divx out of Pinnacle with the 3.11 codecs because I don't immediately understand how I'd handle the audio stream. I guess my question is, is this effect something to pursue within Virtual Dub, or inherent in the DivX codec? As an aside, the de-synching does NOT appear to occur at the avi border appends. However, I will admit that I've used the above approach on ripped DVD files which have been AVI'ed through DVD2AVI without the same noticeable de-synching occuring.

[mevan]

Just a suggestion!
use it with your own caution!!!

See if there is an option in your encoding program to maintain the same sample rate in your input and output files (eg in FlaskMPEG there is a "same as input" checkbox in the "sampling frequency" window of the "Audio" tab).Make sure that option is activated!!!

In general your resulting video file must have the same audio sampling rate as your original (unencoded) file.

Hope I've helped, and if I'm sorry if I have caused any trouble.

[klettke]

Thanks for the suggestion. No trouble at all. I use Lame, with a Razor Lame front end for my encoding, and so do not have the same type of options.
I would however, enjoy some clarification about your statement, "In general your resulting video file must have the same audio sampling rate as your original (unencoded) file." I'm not at all clear what you mean by that. Are you talking about, for example, the 44.1kHz versus 48 or 22.05? If so, that had not occurred to me. That's before Virtual Dub, back in my encoder instead. And, indeed, in this particular situation, I did change that around somewhat. I'll go ahead and try it keeping the rate the same. In the meantime, is there some general reference you can point me to? Or is that in the Flask help file, which I don't use. I'll report my experience with this variation. I'll be on holiday for about a week, so don't expect an earlier response. Thanks again for the suggestion.

[omarh]

Is anyone else pretty disappointed in DIVX?? I mean, the audio sync problems are incredibly annoying and make it almost worthless. I am totally impressed with the video quality of divx, but since it doesn't seem to work right with audio then what's the point?? if I use mpeg-2 or mpeg-1 i never get these stupid audio sync problems.

All I have to do is seek around with media player, or the playa, and it loses sync big time. It looks like an old kung fu movie with dubbing.

[UncasMS]

divx 3.x or better ms v2 DO WORK like a charm with mp3.

dont get me wrong, but using the right tools properly is the magic key.

i wouldnt touch flask anymore (do believe me, i#ve spent month using it some 15 month back from now, and that piece of shit has NOT improved!)

using mpeg2avi or nandub gave/give me almost perfect results.
handle video and audio separately is essential!
have a look at my older mpeg2avi guide to see what i'd suggest for sound extraction and muxing.

[omarh]

i've only used flask so far....

the video flask produces in divx format is beautiful...
so if i use flask for the video, and then extract the audio separately and add it in with virtual dub, will that work?

[UncasMS]

using flask this would be my advice:

video with flask audio as pcm wave (either with flask as separate stream or with vob2audio or dvd2avi).

now mux both: video and audio with virtualdub.
stick to the interleaving values i mentioned in my guide and of course let virtualdub compress the wav to mp3.

this way the avi should be in sync

[omarh]

Thanks for the help UncasMS.

It seems to help a lot. I used dvd2avi, and then mux'ed the audio with the video using virtual dub.

But, here's the weird thing...as long as I use the Playa, its fine! the audio and video are synced really well, not even a second off sometimes, other times its dead on.

BUT, if I use any other player, like Windows Media player 6.4, or BSPlayer, or RadLight, they always screw up the sync horribly!! I wonder why those other 3 players can't play it right but The Playa does. Its weird 'cause in other forum posts, people complain about the Playa and suggest that Media Player is better.

[omarh]

I think I know why the Playa works and the other players don't!

When I run the Playa, my CPU usage is at 70% to 80% while playing a movie.
But if I watch the exact same movie with Media Player 6.4 or BSPlayer or Radlight, they all are at 100% cpu usage.
So I'm wondering if maybe when the CPU is over-taxed like that it can't handle seeks properly and loses sync very easily.

I have a P3 733 mhz with an older VIA chipset (Apollo Pro 133).

maybe its time to start asking for an Athlon XP for christmas hehe

[UncasMS]

omarh, are you by chance using DIVX4????

pretty much sounds like you do.

if you, i'm sorry i have no further ideas.

i dont like divx4 at all and dont use it myself. i prefer nandubs smartbitrate-controlling which works better than anything else i have tested.

[omarh]

You're right, I'm using DIVX 4.11
Several months ago I tried out Divx 3.11alpha, and it seemed to work but the quality (video) was so horrible, I gave up on divx all together.
Then I tried divx 4.02 just for fun and was blown away by the video quality! I think its related to the low motion, fast motion thing...on slow moving parts, the video looked ok, but any time someone would move, you'd get this annoying jerky type of picture...and it was a show stopper for me so I gave up on divx. I think at the time I read that you can encode the fast moving parts using the fasts motion codec, but piecing all those together was just too time consuming!!
Now though, I guess this nanddub technique handles that....

Anyway, i'm really happy with Divx now. I'm doing the audio separately and also I found that if i reduce the quality setting when it plays back divx movies that media player drops down in usage to 90% instead of 100. and that seems good enough to allow for the audio to stay in sync.

The reason I wanted to use 4.11 is because its open source and i was worried that there's no more development on 3.11alpha so wouldn't it be a little dangerous to keep all these movies in that older format???

[omarh]

Uncas, I forgot to say thanks for helping me out.

Thanks!!

[UncasMS]

1) my pleasure

2) nandub does nearly the same that divx4 does: multipass transcoding. first pass is done with highest bitrate to create a statistic file, then comes pass number two, which tries to stick to whatever setting / bitrate you selected.

this is being done with divx 3.x or ms v2
and the quality is awesome, let alone the fact that nandub gives me the exact filesize i set in the beginning. thus my 2cd rips always use the max capacity and dont end up being some 1200mb though i'd love to have 1450

3) i dont think it'll be dangerous to stick to the original mpeg4 codec MS V2 (is one of them). they will always be supported imho.
on the other hand divx 3.x movies can easily behave like they were ms codecs. changing the fourcc code is done within seconds and thus a divx 3.11 avi will pretend to be an ms v2 for example.