How do I make an "mpeg-4 compliant" audio stream ?

[ukb007]

Somewhere I read that, in mpeg-1 > mpeg-4 (DivX) conversions (although not really a good idea to begin with), one has to convert audio also to an mpeg-4 compliant stream before muxing with the DivX4-encoded video stream to avoid audio-synch issues. So how do I transcode the mp2 from the VCD into an "mpeg-4 compliant" mp3 stream?

I'm asking because I sometimes extract the audio from the VCD with GoldWave, reencode into mp3, and mux with the .avi generated by DivX4 low-motion codec in VDubMod, always resulting in a gradually asynch audio. Then I have to take a lot of pain to stretch or shrink the audio to correct this.

Thanks.

[KpeX]

AVI is not mpeg-4 compliant so it doesn't really matter what audio format choice you make. The sync problem is not due to the fact that you're using MPEG-1 audio. I'd recommend transcoding your audio ( if really necessary ) with BeSweet.

[ukb007]

Thanks, Kpex.

The DivX file that I make with VDubMod using DivX4 compression has the .avi file extension. Why isn't that mpeg-4 compliant? I thought DivX is mpeg-4 - but maybe I have a serious misconception here. Correct me please.

Secondly, why d'you think GoldWave might have botched it up? I'd like to know because I use it ever so often. Only in the VCD>DivX transcoding has it given rise to audio synch issue.

[symonjfox]

MPEG1 audio layer 1, 2 and 3 ARE supported by MP4.
I did some tests, recording DVB channels, encoding the video in Xvid and keeping the original audio. It works good!

The bad thing is that some software (like MP4/AAC plugin for Winamp, expects that there's an AAC stream in MP4 container, so if there's an MP2 or MP3 it just freezes). No matter with Direct Show filters.

about MP4 compilance, you should read more in the New A/V Containers forum, and read the Doom9's guide about MP4. ATM is unsafe to use MP4ip / MP4ui programs, since they have troubles with lastest Xvid. Use 3ivX media muxer instead.

Cheers

[bond]

well you have to divide 3 things, when talking about mpeg-4 compliance:
1) the container format
2) the video format
3) the audio format

ad 1) the container format defined in the mpeg-4 standard is .mp4, .avi has nothing to do with the mpeg-4 standard, its just another container format like .mov, .ogm, .mkv, .wmv aso..
ad 2) video codecs which are compliant to the mpeg-4 standard are divx5, xvid, 3ivx, nero digital, ffvfw/ffmpeg aso...
ad 3) the audio format defined in the mpeg-4 standard is aac

now if you want to have a mpeg-4 compliant video stream choose one of the listed codecs and your video is compliant to the standard of course..
but to have a 100% complaint file you will have to use aac (or mp3) and mp4 too (which both are top of the technology available)