Problems with audio encoding

[eymajai]

Hi

I am an unexperienced user of Virtual Dub and I have found a problem when I want to join two avi files, because when I open the first avi file, a message appears in VirtualDub :

“VirtualDub has detected an improper VBR audio encoding in the source avi file and will rewrite the audio header with standard CBR values during processing for better compatibility. This may introduce up to 16351 ms of skew from the video stream. If this is unacceptable, decompress the *entire* audio stream an uncompressed WAB file and recompress with a constant bitrate encoder. (bitrate: 117.2+/-11.8 kbps)”.

The question is that I do not know how I must do this job, because I do not understand VBR, CBR, etc, audio encoding. Also I do not know how can I decompress the audio stream in an uncompressed WAB file and also how to recompress with a constant bitrate encoder.

Also I do not know why VirtualDub indicates a bitrate of 117.2+/-11.8 kbps.

Can you hep me?

Thank you in advance and best regards.

[Lecter]

The question is that I do not know how I must do this job, because I do not understand VBR, CBR, etc, audio encoding. Also I do not know how can I decompress the audio stream in an uncompressed WAB file and also how to recompress with a constant bitrate encoder.

Hi. I'm a VirtualDubMod user, but the procedures are very similar. The audio stream must be switched to "Full processing Mode". Then go to "Compression" and select "No compression (PCM)". Finally go to "Conversion" and select the same audio features that the original stream ones (i.e. 44.1 Hz, 16 bits...) Then, click "Save wav" and you will get an uncompressed PCM wav of about 1 GB of size. Then you can convert it to the suitable audio format with headac3he for instance.

I hope this could help you

PD: Sorry for my bad english :rolleyes:

[eymajai]

Hi Lecter:

Thank you very much for your explanation. I will try and I say you my results.
A last thing, Which one is better to work, VirtualDubMod or VirtualDub?

[Lecter]

VirtualDubMod has more features than virtualdub because the source code has been adapted. As you may read in the VDM help:
VirtualDubMod is a project that was born when suddenly a lot of modifications to the original VirtualDub by Avery Lee sprung up, mainly on the Doom9 forums. Some people got tired of needing several diffrent modified VirtualDub executables, so the idea arose to put them all together into a single app, VirtualDubMod.

Greetings

[eymajai]

Thank you Lecter for your explanations.
Did you know the differences between Nandub and VirtualDubMod?

[Asmodian]

Nandub is a very old modification of vdub and is designed for encoding with to divx3.11 and will not encode with any other codec.

VdubMod is very new (still being developed) and is basically a more feature rich version of vdub.

You also don't need to re-encode your audio - this will cause quality loss and with a source at that low of a bit rate (117.2+/-11.8) I would try to avoid that. Just use vdubmod and tell it not to change the header when you open the file and it gives you a similar message (use Nandub like audio processing) and save to your file to a matroska or ogg (something that supports vbr audio properly).

[eymajai]

Thank you for your help Asmodian. I will follow your ideas and will try VirtualDubMod

[galapogos]

Originally posted by Asmodian
Nandub is a very old modification of vdub and is designed for encoding with to divx3.11 and will not encode with any other codec.

VdubMod is very new (still being developed) and is basically a more feature rich version of vdub.

You also don't need to re-encode your audio - this will cause quality loss and with a source at that low of a bit rate (117.2+/-11.8) I would try to avoid that. Just use vdubmod and tell it not to change the header when you open the file and it gives you a similar message (use Nandub like audio processing) and save to your file to a matroska or ogg (something that supports vbr audio properly).

Hi,
How exactly do you save to ogg/matroska? Can I use direct stream copy? Is there no way to do it with avi?

[stephanV]

you save to matroska or ogm (not ogg!) just by going to file-->save as and then select the output method. you can use direct stream copy with this.

and yes, you can save just as fine in AVI.

BTW - i believe VirtualDubMod development has slowed down to a halt for the moment.

[therealjoeblow]

Originally posted by eymajai
Thank you Lecter for your explanations.
Did you know the differences between Nandub and VirtualDubMod?

Nandub is OLD. VDM is a newer progression of what Nandub was, a modification of Avery Lee's original Virtualdub wit some additional features.

Don't use Nandub! Nandub doesn't split files correctly. It discards some audio samples at the split point. No big deal if all you want is a permanent split, but heaven forbid you should ever want to rejoin those split files back into one. You'll end up with audio desync on the 2nd half. See mo other post about this:

http://forum.doom9.org/showthread.php?s=&threadid=85114

Use VDM instead.