Safe to Re-encode "Packed Bitstream" Xvid File?

[adalect]

Hi there,

I have a couple of Xvid files that are made up of GMC's, BVOPs, and VBR MP3 audio track. All of these files also have packed bitstreams. My goal is to have these files play in my standalone Xvid player. Of course, the characteristics above are known to choke many Xvid players. So my plan is to re-encode all of these files to something more compatible.

I have re-encoded files that involved GMC's, BVOPs, packed bitstreams, and VBR MP3 audio before. The results have been very successful.

Here's my question: do I need to unpack the Xvid files (so it's originally packed bitstream, and now it is normal), before I re-encode? I am not sure if leaving the files as is (before re-encoding) will cause problems, so I thought I'd ask.

If anybody is wondering, here is the script I usually use, before importing the file to VDM to work with:

Directshowsource("Original-Video.avi", fps=29.97, convertfps=true)
# Where the FPS indicator is for the actual frame-rate of the original video file.
# I find leaving the FPS modifier on ensures that audio and video stays in sync

Any help would be appreciated. Thanks!

[netmask56]

You can unpack these files with avidemux - no re-encoding necessary. Takes only a few minutes unless you have a very slow computer...

[jagabo]

You can unpack these files with avidemux - no re-encoding necessary.

Xvid's 3 warp point GMC will still be a problem.

[jagabo]

f anybody is wondering, here is the script I usually use, before importing the file to VDM to work with:

I

Directshowsource("Original-Video.avi", fps=29.97, convertfps=true)
# Where the FPS indicator is for the actual frame-rate of the original video file.
# I find leaving the FPS modifier on ensures that audio and video stays in sync

DirectShowSource isn't frame accurate. AviSource() would be better. But if you're not doing any filtering in AviSynth you might as well open the files directly with VirtualDub. Recent (the last few years) builds don't have any problem with VBR MP3. You may get a warning about the VBR MP3 but the file you make should turn out ok.

[adalect]

If anybody is wondering, here is the script I usually use, before importing the file to VDM to work with:

Directshowsource("Original-Video.avi", fps=29.97, convertfps=true)

...if you're not doing any filtering in AviSynth you might as well open the files directly with VirtualDub. Recent (the last few years) builds don't have any problem with VBR MP3. You may get a warning about the VBR MP3 but the file you make should turn out ok.

Oh yeah! I forgot about that. I usually use the above script for .mkv files (just change the extension in the script), since I find .mkv files always have some sort of audio problem if I do otherwise.

I am currently using VirtualDubMod 1.5.10.3 since I that historically works. Since our objective is just a simple re-encode of an AVI file, I opened the original file in question directly in VDM, as suggested. This is what happens:



So I get a warning about VBR audio streams and re-writing headers. I have done a bit of research on this, and have read that if I click "No" and then fully re-encode the audio with "Full Processing Mode" and something like LAME MP3, the resulting video should not have any audio sync problems. Is this true?

Of course, I would also be re-encoding the video portion to get rid of the GMC problems too.


Thanks for the help so far!

[netmask56]

AviReComp I suppose?

[manono]

So I get a warning about VBR audio streams and re-writing headers. I have done a bit of research on this, and have read that if I click "No" and then fully re-encode the audio with "Full Processing Mode" and something like LAME MP3, the resulting video should not have any audio sync problems. Is this true?

If there's nothing wrong with the current audio, why reencode it? Click 'No' to the question and keep it on 'Direct Stream Copy'.

[jagabo]

So I get a warning about VBR audio streams and re-writing headers. I have done a bit of research on this, and have read that if I click "No" and then fully re-encode the audio with "Full Processing Mode" and something like LAME MP3, the resulting video should not have any audio sync problems. Is this true?

Yes. I seem to recall that sometimes you have to select Yes instead of No.

If there's nothing wrong with the current audio, why reencode it? Click 'No' to the question and keep it on 'Direct Stream Copy'.

Some old players don't like VBR MP3.

[manono]

Some old players don't like VBR MP3.

I had thought of that but since he didn't mention anything about reencoding it as CBR, I didn't think that was what he was thinking of doing - that just the act of reencoding it would somehow keep it in synch.