wav and mp3 why the difference ?

[cpuuk]

When creating a DivX I usually end up with a choice of sound to encode from the ac3 source file (wav or mp3). How come when I mux a DivX avi & mp3 the sound is usually in sync. Yet when I mux DivX avi & wav the sound is usually off at around the 50 minute into the film.

Why does mp3 sound track stay sync’d, but wav doesn’t?

Using the usual stuff Gordianknot, Nano, VD etc

[DJ Bobo]

You still have place for a whole 1536kbps WAV??!!

Anyway, there is no reason for that, they are all synch, it doesn't matter if WAV or MP3, you must be doing some wrong things (which I can't guess since I hadn't such a problem before)

And if you still have place for a whole WAV, why not make the video look better and compress the audio to MP3?!

[cpuuk]

I have 120G drive, so space isn't a problem.

OK, you tell me what you would do to do a final mux of avi & wav file using say VD, just reference the audio options (as I have no problems with the video options)......

[DJ Bobo]

I never changed any audio options, not for wav and not for mp3 (Except delay of course). All is on default settings.

[cpuuk]

I've been testing, and the audio codec that I use when doing wav to avi mux, is DivX3.11. It looks like this codec is what is introducing the audio sync error, as I tried MSadpcm codec instead (thios added 250M to final avi) and that sync'd perfectly into the avi.

So I have 2x questions-
1. Anyone know why good old alpha 3.11 audio creates this sync problem?
2. Is there a wav (or similar) to avi codec that I can mux with? OgVo perhaps?

PS I can't use mp3 on my PC, hence the need for wav or something else playback support.

[Got Milk?]

I don't know the details, but there was a well known problem with DivX 3.11 audio becoming out of synch. As I only use MP3, I don't know much about other compression formats, but OggVorbis is meant to be good at low bitrates.

How come you can't use MP3 on your PC?

[cpuuk]

Oh the usual problem of WMP6.4 stop working with avi MP3 (ie no sound). I've asked a gazzillion times if anyone knows how to re-enable WMP with avi packaged mp3, but never an answer :-(

BTW WMP plays ordinary MP3 ok, just not avi MP3.

[DJ Bobo]

and how is it in other players, like BSPlayer?

[cpuuk]

BSplayer - sound but, no video.
DivX Player - sound\ video OK (just), but Player is, well you know how player is ;-)

[DJ Bobo]

switch to overlay mode2 in BSPlayer

[cpuuk]

Mode2 got the video& audio up, thanks. AVI audio playback is wave only though, BSP will not playback VBR encoded MP3 AVI- is there another switch?

[DJ Bobo]

BSPlayer plays all things, VBR or CBR, all works.

Your system is weird anyway, you should reinstall your windows.

Entre nous, VBR is nothing sensational, CBR is good enough.

[cpuuk]

I could re-install windows, but somewhere along the line the playback problem happens again, the only thing I can think of is IE6 might cause this problem? I have 3x systems with this same playback problem, but I do have a new system that doesn’t and it is running with default IE5.

OK, back to my original question- To summarise, it looks like 3.11alpha AUDIO has always been broke, and does introduce a skew error (not the same thing as the audio offset) in it’s encode. Usually I fix this by adjusting the frame from 25fps to say 24.9991fps after the muxing has completed. This fix is ok for PC but not for making (S)VCD as their playback fps is fixed.

Anyway, thanks for being a sounding board, I now have some crazy ideas about how I can counter the alpha skew problem.

[DJ Bobo]

DivX Audio is also synch... if you make the right settings! the settings are given in some help file coming with DivX3:

Use VirtualDub to
compress and multiplex Audio with Video
Select your AVI video file,
Video -> Direct Stream Copy
Audio -> Interleaving -> 500 ms of audio before video start
-> Interleave audio every 500 ms
Audio -> Compression -> Choose DivX ;-) Audio at 64Kbps for DivX ;-) Video
Audio -> Full Processing Mode
Save the final AVI

[EDIT]
As for your MP3 problem, try to install an mp3 directshow filter, I think there is one on the doom9 download page

[Slogra]

Have you ever tried 320kbps mp3? I think this will stay in sync and it will sound just as good as the wav.

Ogg is ONLY good for lower bitrates (< 100kbps)

You can only use 64kbps for divx audio so this ain't good either.


(edit: ooops, i just read that mp3 doesn't work at all. It works ok on my mediaplayer 6.4 with fraunhofer codec).

[cpuuk]

DJ- Hmm, the only setting that is different that I have, is interleave is set 1 frame, rather than 500ms. As long as your setting isn't being confused with preload (also 500ms) it's definitely something to try (I'll report back).

Will try mp3 DSS.

Slogra- No, as I only ever use wave (OK KN is making me use 128k mp3). Like I said above, something I install kills the mp3 avi playback, but I don't know what. I have 1x system that works OK, but 3x system that can't playback mp3 avi thru WMP.

Hey don't knock divx audio, it may be 64K but it sounds good and makes for a nice small avi :D

[goldseal]

i used a whole wav for terminator and about 2 gig for the film the wholes things about 3 gig and the synch is fine used divx5

[cpuuk]

Which wav codec ?

[DJ Bobo]

Originally posted by cpuuk
Which wav codec ?

There is no wav codecs! :p

[cpuuk]

So godseal post just confirms what I said said, and in fact has no bearing on solving the divx audio codec problem :(

Like I said I have no problem making mp3 avi, just playing them back :)

[DJ Bobo]

@ cpuuk
Have you tried the super tips I gave ya? :D

[cpuuk]

Unable to find filter on Download, still looking for ....

[DJ Bobo]

awwa! sorry! it vanished! I also did a small search with google, but havn't found a working link, damn!

But hey! I got something for ya! *may be* it will solve your problem! what about installing the latest DirectX version?

[cpuuk]

Nice thought, but already on dx8.1.

Say does OgV have a codec, I can only find some OV conversion progs?

And yes, I've tried Nemo as well :(

[diji1]

@cpuuk : is there actually any quality gained by extracting the ac3 to wav ? am i wrong in thinking that there would be no sound difference between ac3 and wav extracted from that ac3 ?

[cpuuk]

It's not a quality question, its a "can I play it back thru my player" question :)

Guys, I don't want to tax anyone's times unduly, I just wanted to know why after making 200+ divx files, my wav sound was always "off". This only really came to light when I switched from mpeg2avi to Gordian Knot, which produced mp3 sound in perfect sync.

The playing back of mp3 or wav has just been an annoyance, which I get round by using 2x different players (WMP for wav, Player for MP3). I just wondered if a fix existed, as I went thru this question a year ago.

I continue to thank you for your suggestions on things to try, if it can't be fixed, so be it :D

[cpuuk]

Woah! Just wondered into the the twilight zone. After my experiments I decided to restore a backup of my system. As I was so impressed with BSP (thx DJ) I installed it again with a view to replacing Player2, and lo and behold it now plays the mp3 or wav encoded avi- spooky! :D


UPDATE

Sorry, I was in Twilight zone, the files I thought were mp3 were in fact regular wav (mis-lablled) :confused: