Topic: synch sbd audio to dvd

[yousef]

What about the situation where my audio source is definitely spot on (ie - taping audio with a 744t) and it may be the video that is drifting? Is it possible or wouldn't it be better to stretch the video rather than an audio source that is correct?

I don't think it is an issue of one source 'drifting' as such - more that different clocks or crystals or whatever it is inside the recording gear leading to very slightly differing sample rates. So I'm not sure if you could say that one or the other source was the 'correct' one.

That aside, I've found the results of time stretching audio to be far more acceptable than those when doing the same to video - either the medium or the eye is much less forgiving and the overall effect seems quite unnatural. YMMV, of course...

[guitard]

b)  Compare the timing of the two files to determine if the SBD needs to be stretched or shrunk to match.  I do this by choosing a continuous run of music that exists on both the SBD and the stripped audio.  I then select two distinct points in the music (usually a drum hit) at the beginning and end of the sample (the longer the sample the better).  Use the software to shrink or stretch the SBD audio to match the stripped audio.

What about the situation where my audio source is definitely spot on (ie - taping audio with a 744t) and it may be the video that is drifting? Is it possible or wouldn't it be better to stretch the video rather than an audio source that is correct?

There are a few things you have to keep in mind regarding video and audio ~

Video is frame rated, i.e., 30 frames per second for NTSC video.  So in terms of "stretching" it, it's not the same as changing the length of an audio recording.

Now, of course, some might say, but I have a video tape that is all out of whack with the video slowing down, speeding up, etc., etc.  But that's not a case of the *video* getting stretched ~ it's the *tape* on which the video is recorded.  And when you put that analog video in the digital realm, short of snipping out or adding frames, you can't easily "resize" it.

So the short answer to your question - it's probably better to alter the audio, rather than alter the video.

There are some exceptions though.  Let's say you have a concert video and in between songs, the picture is pretty much black when the stage lights are down.  You can easily go in and snip/add a frame or two (or three, four....however many are necessary) and no one will ever know you altered the video.