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| miqrogroove |
 Posted: Dec 17 2002, 08:06 PM |
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VDub has been plagued for all time by a bug in Append AVI audio sync. I emailed the virtualdub.org webmaster a few times but nothing ever came of that. Does anyone know about this problem? Video captures work fine, but any time I append and edit AVI files the audio sync is drastically screwed up.
Help if you can.. I've been trying to make this work for years.
p.s. Using divx and mp3 if you need to know.
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| fccHandler |
| Posted: Dec 17 2002, 09:12 PM |
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I think the problem is not VirtualDub, but the fact that your audio is compressed. Look at this topic:
Joining Avi Files
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May the FOURCC be with you... |
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| miqrogroove |
| Posted: Dec 17 2002, 09:17 PM |
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This is absoultely not the case.
Are you saying that I must append and then save before compressing? That seems like an unnecessary step. What I am doing now is appending files, editing (still uncompressed audio), setting the compressor to MP3, and then saving. If this "feature" is not intended to work, then that would explain a lot!
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| miqrogroove |
 Posted: Dec 17 2002, 09:22 PM |
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In case that was unclear, I am experiencing this problem with uncompressed AVI files. The problem occurs during the compression process. |
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| fccHandler |
| Posted: Dec 17 2002, 09:47 PM |
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| QUOTE (miqrogroove @ Dec 17 2002, 05:17 PM) | | Are you saying that I must append and then save before compressing? |
No, I wasn't saying that. But since you mentioned it, and if (as you say) the problem appears during compression, then that suggestion should produce a perfectly synced uncompressed AVI. Have you tried it? Because if that works, then the compressor(s) are at fault, not VirtualDub.
One other thing: If the audio is short on any of the segments you're appending, then all segments added after that will be out of sync. (I think I mentioned that in the topic pointed to above.)
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May the FOURCC be with you... |
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| kaisersox |
 Posted: Dec 20 2002, 09:25 PM |
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I have a similar problem .
I have encoded ( xvid+ mp3 128kbps) some vob files in different times .
the singles avi files appears to be perfecly sinch. , but when i try to put them togheter I obtain a movie that seems to be non in sinch a little from the second file ,badly from the others.
Do you think that the problem is that also the original files have different duration of video and audio ( but only in the end, so I can't see/hear this???)
Thanks for your support , sorry for my bad english
K. |
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| miqrogroove |
| Posted: Dec 20 2002, 09:44 PM |
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fccHandler:
I tested the Append AVI feature as recommended. I captured 5 files, each 30 seconds or more in length. I appended them together and did no editing other than that. Each source file was captured using DIVX 5 Pro and WAV audio (44k, 16bit stereo). I selected direct stream copy for both video and audio.
The resulting AVI file was badly desynchronized after the first 30 seconds, and the problem was increasingly appearent after each transition.
My initial assumption that the fault lies with Append AVI, and not the compression system, appears to be correct. |
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| phaeron |
| Posted: Dec 20 2002, 10:23 PM |
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The append functionality is meant to be used for segments that were explicitly split apart from one video programmatically, and doesn't resynchronize in order to avoid gaps in the streams. When you capture multiple videos, the audio and video streams in the video files don't have the same length and thus can't be successfully joined in this manner.
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| fccHandler |
| Posted: Dec 21 2002, 05:45 AM |
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(To augment what phaeron said)
You must ensure that the audio and video of each segment is exactly the same duration before you append. The method I described in the other topic will work, but it's awfully tedious. As an alternative, you could try Avisynth's AlignedSplice() function.
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May the FOURCC be with you... |
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| miqrogroove |
| Posted: Dec 24 2002, 05:54 AM |
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Good lord. Let me paraphrase what you are saying:
#1 AVI files captured by VDub cannot be appended together seamlessly.
#2 Copying the audio stream to a WAV file, performing a menial operation on that file, and then reprocessing the whole mess will fix the problem.
#3 There is no easier way to do this using VDub.
Excuse my grumping but I think some programmatical enhancement of VDub is in order. |
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| fccHandler |
| Posted: Dec 24 2002, 07:27 AM |
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| QUOTE (miqrogroove @ Dec 24 2002, 01:54 AM) | | #1 AVI files captured by VDub cannot be appended together seamlessly. |
They can, if and only if the audio and video are the same duration. Otherwise, your AVIs are (in a sense) corrupt.
| QUOTE | | #2 Copying the audio stream to a WAV file, performing a menial operation on that file, and then reprocessing the whole mess will fix the problem. |
True.
| QUOTE | | #3 There is no easier way to do this using VDub. |
As phaeron said, the program is not designed to do what you are asking. Quit grumping and give Avisynth a try and u will be happy I think.
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May the FOURCC be with you... |
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| Shaker |
| Posted: Dec 26 2002, 11:45 AM |
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I am a user with the same problem of desycronisation in Virtual Dub.
I read all of your postings but the problem occurs in a different way on my system:
When I have ONE big AVI (Vid: DivX 5, Aud: mp3) that still contains the commercials and I cut them out of the stream in Virtual Dub I get the same desync as if appending 2 AVIs together. Seems like the mp3-stream from of the section after the cut out slides into and fills the gap of the section before the cut out.
But why is there a gap after deleting something? I don't want to save each section to a file and re-append them together...... (even if that might work)
Apart from this and to compensate all the criticism - Virtual Dub is a cool peace of software and the programers have done a good job :)
Greetings; Shaker |
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| miqrogroove |
 Posted: Dec 26 2002, 05:30 PM |
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| QUOTE (fccHandler @ Dec 24 2002, 02:27 AM) | | QUOTE (miqrogroove @ Dec 24 2002, 01:54 AM) | | #1 AVI files captured by VDub cannot be appended together seamlessly. |
They can, if and only if the audio and video are the same duration. Otherwise, your AVIs are (in a sense) corrupt. |
So what you are saying now is that it is normal behavior for Virtual Dub to capture corrupt AVI files?
-- Confused |
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| fccHandler |
| Posted: Dec 27 2002, 04:09 AM |
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@miqrogroove:
Sorry, my describing the AVIs as "corrupt" wasn't really accurate; I apologize. But I know that it's extremely rare for the audio and video of a capture file to be exactly the same duration, because of minute variations in timing between the video card and the sound card. It's a common problem with all kinds of capture hardware (mine too), and not really VirtualDub's fault.
Also, what exactly are you trying to do, that you would make a number of captures and want to paste them together seamlessly without some kind of cutting?
P.S. Did you ever try Avisynth?
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May the FOURCC be with you... |
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| fccHandler |
| Posted: Dec 27 2002, 04:17 AM |
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@Shaker:
Your cutting problem occurs because the audio has been compressed to MP3; this format doesn't allow precise editing. Whenever possible use uncompressed PCM while editing, and compress to MP3 later. In your case it will probably be necessary to decompress the audio before making your cuts, and recompress it afterwards.
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May the FOURCC be with you... |
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