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February 19, 2002 01:16 AM

Categories: Upgrading

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blackwolf5710

Pending Member
Joined: 01/26/2002

I have been experimenting with the Video/Audio sync issues and have arrived a the following:

TivoApp V2
1. If I use this to extract file as a single MPEG2 file, it plays totally out of sync requiring a lot more work to fix.
2. If I extract as seperate audio/video files, the video is fine but when I load the audio into Soundforge I can see numerous "peaks" (anomolies) throughout.
3. If I extract the TyStream as seperate chunks, I cannot find a way to seemlessly connect them without a audio/video glitch.
4. Extracting the TyStream as a single file is fine...Then:

TyConvert--
1. If used to convert the TyStream to one .mpg file, it has numerous audio/video anomolies throughout as well as the audio goes out of sync even with "sync audio" checked.
2. If used to convert to seperate audio/video files the audio file is fine when loaded into Soundforge (strange since Tyconvert is the program TivoApp uses..hmmm) but-- the video WILL have a 2-3 frame glitch with horrible anomolies at every point where the tyStreams were connected (approx every 11 minutes and 10 seconds.)
Also-- TyConvery does not give an audio offset value so I can't use the Video from TivoApp and the Audio from Tyconvert.

THEREFORE:--
Splitstream. This program seems to produce a flawless video (.m2v) and audio (.m2a) with no glitches or anomolies in either. PLUS it gives you an audio ofset value that can be used in the actual encoder. SplitStream actually gives you two audio offset values when it starts the conversion. If you watch the conversion it will display a caution message at every point in the TyStream file where the "segments" were joined by TivoApp. It will ALSO give you a Audio time and Video time. THESE WILL BE DIFFERENT by approx. the amount of one of the audio offsets it gave at the start of the conversion. Whichever of the two audio offset values is closest to the difference is the one you will use in the encoder. IN EVERY CASE for me SO FAR--it has always been the larger, first number.

SO-- in summary:

1. TivoApp V2 to get a single TyStream (File.ty)
2. Splitstream to get a seperate, glitch free audio/video files (file.m2v and file.m2a) and the correct audio offset to be used in an encoder.
3. Use the .m2v, .m2a, and offset value in your favorite method of encoding to whatever format you are trying to do.

This is as fas as I have got so far and I certainly have not tried EVERY method available so if someone has any better suggestions--plesae post.

Otherwise--hope this helps the effort.

Discussion:    Add a Comment | Comments 1-2 of 2 | Latest Comment

February 22, 2002 1:09 PM

I just wanted to second this opinion. At present, the above is the method which works best for me.

I am about to experiment with VirtualDub as the editor (instead of selecting clips from with-in TMPGEnc), frame-serving to TMPGEnc to produce a single MPEG. I'm afraid VirtualDub may introduce additional audio skew. Will post findings.

February 25, 2002 3:55 PM

I've tried this method now and, never having used splitstream before, I see that I get a variety of different offset messages throughout the extraction. Shall I ignore the offsets displayed on subsequent chunks because they have different deltas than the 1st pair of offsets displayed?
Also, the audio file is about 4 seconds shorter than the video file (1 hour show) when I drop them into Mediastudio. Yet the offset values I see are in the milliseconds (70-150). Could this relate back to the frame rate discrepancies of 29.97 vs 24.xx (I forget the rate now) someone had posted fixing the problem.. or the sound sample rate shift that someone had mentioned?

Discussion:    Add a Comment | Comments 1-2 of 2 | Latest Comment

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