Re: Media Centre-Vista- Lipsync

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"Questor" <Questor@xxxxxxxxxxx> wrote in message news:Ol5G3LtjJHA.4644@xxxxxxxxxxxxxxxxxxxxxxx
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Not so much different drivers maybe but different pieces of hardware capturing the audio and video streams during recording. TV capture cards introduce a time delay to accommodate special viewing features like pause. There's no problem if the audio stream is also routed through the capture card but in some cases during recording the audio stream bypasses the capture card straight to the PC sound device which results in the sound being out of synch with the time delayed video.

"Questor" <Questor@xxxxxxxxxxx> wrote in message news:u6mXV4sjJHA.3380@xxxxxxxxxxxxxxxxxxxxxxx
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Loss of audio/video synch is a frequent issue in digital transmission: if you ever subscribed to any of the satellite services you would be very familiar with this.
The problem is in the signal source, not the recording medium.

I don't believe this to be true at all. I've subscribed to DirecTV for over 10 years and have NEVER had any of my channels be out of sync between voice and picture. TV cards inside computers tend to have individual drivers for voice and video. If either of these drivers are delayed by higher priority interrupts, the sound could very well get out of sync.

Questor


That's what I was alluding to. Hardware drivers. Several years ago I had an ATI All-In-Wonder (TV) card. If I used the direct video input all was fine, but if I relied on the 'cable' input, there were times that audio and video got out of sync. What stopped it was to make sure that nothing was running in the background that would steal cycles away from the CPU. Of course, the CPU speeds back then were pretty slow compared to all the new stuff out there so this argument might just be smoke and the original problem may be deeper.

Questor

There are other possibilities, like working with AC3 audio or variable bitrate MP3 audio tracks. Both can easily become out of synch depending on what you do with them. I've got another scenario where the direct audio from my TV tuner card isn't recognized by a lot of capture software. It would be very easy to miss the fact that video and audio streams were not coming from the same place.. say direct TV capture for the video track but line in for the audio, which would result in out of synch sound.

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