Strange project

[Manngo]

Hi!

I have the crazy idea, to use avisynth to decompress audio from an avi file. The avi is divx3 and the audio is mp3 VBR. The audio streem seems to be broken, Vdub(mod) can not properly decompress it to wav (it decompress it, but loose about 3 sec inside the stream, and from that point audio is earlyer than video with 3 sec). The avi PLAYS FINE, without errors. I can watch it with media player classic. So I think, that my directshow codec can decompress audio well, while acm used by vdub not (as I know acm does not support VBR MP3).

I tryed to frameserve with avisynth to vdub. The script was only 1 line: avisource. It played also fine. Vdub fileinformation said, that the avs cosisted of an uncompressed video and an uncompressed audio stream. I saved audio as wav. Partial success: from a point the resulted audio is silent, however the length is correct (not loosing the 3 sec). Problem starts about the same point where the 3 sec loss appears in the stream when decompressing with Vdub.

Questions:
When frameserving with avisynth to vdub I use the directshow codec to decompress the audio?
What can couse the silent problem?

[bond]

why not simply create a graph in graphedit and decompress the audio there? no need to go the way via avisynth and vd

.avi (file source) -> avi splitter -> mpeg layer3 decoder -> wav dest -> .wav (filter writer)

[Manngo]

I'm thinking about handling the problem is DVD2SVCD. It's routine could not decompress the audio properly.

[Manngo]

I did exactly the same you said (with graphedit). The end of the wav file is half an hour silence, however in the avi there is sound.

[bond]

hm MPC has an own mp3 decoder afaik, try disabling mpc's mp3 decoder in the mpc options to force it to use the default windows one and report whether it still works fine during playback

[Manngo]

The avi plays also with win media player.
Gspot can render it and report no problems.
But: Gspot says it is mp3 CBR, Vdub saya it is mp3 VBR.

[stephanV]

thats fishy... also that it will play in WMP but that graphedit cannot extract it properly...

what if you use directshowsource() with avisynth instead of avisource()?
also, if you frame serve with avisynth to VDub and you only try to extract the last piece of audio (say last 5 minutes), does that work?

[Manngo]

Yep!
avs->Vdub works for the last 5 min. It saves the 5 min wav.
When I open the avs in graphedit I see:
avssource->matrixmixer->morgan stream switcher->default audio renderer
I have already tryed directshowsource. The same.

[bond]

very strange, basically the directshow graph shouldnt differ whether you play the file in wmp or graphedit

what happens if you open the avi in graphedit, dont change anything in the graph, play the file there and seek to the place where the troubles start - does it work as in wmp?

[Manngo]

Played with graphedit, as U said. No problems. The audio is in sync till the last second. And nothing is missing.

I also tryed adding resampleaudio(48000) to the avs, but solved nothing.

@bond

The directshow graph is not different. It is exactly the same. (I can see the used filters right-clicking on dvobsub, that is the video renderer). Just work in playing back, and in saving not.

I should use filewriter or dump to save the audio file?

[stephanV]

i guess you could try to extract the audio in two parts, one part before trouble point and one part directly after trouble point... or something like that...

weird problem :rolleyes:

edit: dump might be worth a try

[bond]

Originally posted by Manngo
The directshow graph is not different. It is exactly the same. (I can see the used filters right-clicking on dvobsub, that is the video renderer). Just work in playing back, and in saving not.

I should use filewriter or dump to save the audio file?filewriter
dvobsub is for subtitles, try unistalling it to be sure it doesnt kick in badly