Wierd AVI fault

[lincspoacher]

I bow to the superior knowledge of those who post here...........

Ive got a wierd AVI problem. Its a 650 Mb AVI, containing 12 music videos. It plays fine as is, but i want to snip it up into individual tracks.

I load it into Sony Vegas 6b, and the first thing that happens is that halfway through building the audio peaks (at exactly 46%) it says it has encountered an error and cannot complete the task. So I drag it into the edit pane, and I have a video track and an audio track with no peak information.

The next thing you notice is that the audio is out of synch. in fact to get it in synch on the last track, i have to stretch the 52 minute audio track by another 42 seconds.

But that doesnt synch it in the middle, so in fact, i cant get the whole track in synch in one go.

I started to chop the tracks out one by one, stretching the audio to match. AT track 5 it goes wierd. The start is out by about 5 seconds, but no matter what i do, (including ALT drag and ALT shift drag) the audio refuses to move relative to the video. I simply cannot get the two to match up.

I tried converting to an MPG using WINMPG converter, I end up with an MPG that plays fine in DIVX but still has the out of synch probelm when loaded into VEGAS.

I have d/loaded the latest K-Lite codec pack (2.41 full), and ive run out of ideas (but i concede I am a newb at VEGAS as well, but this is the first thing ive tried thats stumped me)

Anyone got any ideas/suggestions/comments, all gratefully recieved

[guns1inger]

First guess - the audio is VBR MP3. Vegas does not like this at all. Load the avi into virtualdub and say no when the error message appears. Now set audio to full processing mode and save the audio out as an uncompressed wav file.

In vegas, delete the audio track with no peaks, and add a new audio track containing the uncompressed wav. You should now be sweet.

[lincspoacher]

Absolutely spot on!!! It produced a 12Mb WAV file with perfect synch, although the original was 2 channel not 5 channel. The quality is a bit down, buts thats cos I think I set the sampling rate too low, ill do it again at best quality now I have an idea of the size of the file.

Thank you very much, I shall be your bitch if we ever meet in jail....
;-D

Steve

[guns1inger]

12mb wav file - that's not uncompressed. 52 minutes uncompressed should be around 500 mb. That might explain why the quality is so low.

[DarrellS]

The quality is a bit down, buts thats cos I think I set the sampling rate too low, ill do it again at best quality now I have an idea of the size of the file.

It's because you didn't follow gunslinger's instructions. He didn't tell you to set the video compression to a low bitrate MP3, he told you to save an uncompressed Wave file.

[lincspoacher]

The quality is a bit down, buts thats cos I think I set the sampling rate too low, ill do it again at best quality now I have an idea of the size of the file.

It's because you didn't follow gunslinger's instructions. He didn't tell you to set the video compression to a low bitrate MP3, he told you to save an uncompressed Wave file.

This is true, I am guilty of experimenting with the settings, but he was absolutley right, i set to uncompressed and got a 520Mb file of top quality.

Ok, explain this to me then: how come the audio in the AVI is good, but has to be compressed in order that it fit into 650Mb along with the video data, yet to get the WAV to best quality , it needs 500MB uncompressed. How does the AVI compress the audio without degrading it, wheras the WAV cant ?

[DarrellS]

Ok, explain this to me then: how come the audio in the AVI is good, but has to be compressed in order that it fit into 650Mb along with the video data, yet to get the WAV to best quality , it needs 500MB uncompressed. How does the AVI compress the audio without degrading it, wheras the WAV cant ?

The audio in the AVI sounds good to you but it is only an acceptable high bitrate MP3, not a high quality audio file. The uncompressed Wave that you made is no better that the original MP3, it is just better that the MP3 that you made since you compressed it to such a low rate. The only reason that you needed the uncompressed file was to fix the VBR audio.

The person who made the AVI that you have probably started off with a lossless compression AVI with uncompressed WAVE audio.

He had to compress his multi GB AVI capture to DivX compression and compress his 500+ MB audio file to MP3. He just made the mistake that most people are making these days and used VBR MP3.

An audio cannot be compressed without losing quality and the quality cannot be improved by uncompressing it. You might be able to fix some things with an audio editor but just uncompressing the file will not make it better quality, just a much larger file.

As for your other statement. Yes, experimenting is good when your working on your own. You can figure alot of stuff out that way and it's possible that you could've figured this problem out in a few weeks time but when you are following instructions, it's good to follow them step by step.