MPEG Audio Kills All Audio.

farss wrote on 5/15/2009, 6:59 AM

This is truly wierd, even for Vegas (8.0b)

I'm trying to cut a short piece of video from one DVD into another DVD. Main program was recorded on a STB DVD recorder, it's a funeral, not that it makes any difference.

STB DVD's VOB goes onto the T/L just fine, waveforms and thumbnails as they should be. But no sound, absolute silence, not a meter stirs. Thinking I've stuffed up something I add a wav file of some music. Nothing but silence, nice waveform though.

Just to be sure I start a fresh project and add same music file. It plays just fine. Add same VOB file as tried in first project. Looks OK but zero sound. Play music again, fine. Play VOB for a while just in case, no joy. Move playhead back to music. Now silence from it too??.

Save and close project and the symptoms remain the same. The only thing unusual, that I've never had to deal with before, is the VOB file has mpeg audio according to it's properties. I can understand that maybe Vegas doesn't have a clue how to decode this but it seems able to decode it to draw a correct waveform file. The really big mystery here is how did the mpeg audio infects the rest of the timeline as it was played and then kill all the audio. That's truly wierd.

So I guess I'm going to somehow have to find a way to convert this mpeg audio into something else. If no ones got any bright ideas I can just playout the DVD and record the audio so don't sweat too much over this, in fact I would have done this and not mentioned my problems if it weren't for this wierd virus like effect the mpeg audio is having.

Bob.

Comments

farss wrote on 5/15/2009, 7:30 AM

Update:

Tried attacking this another way. Used Vegas's Import DVD Camcorder function. That for some unkown reason split the VOB file from the disk into 6 mpg files. Somewhat amazed to discover that they played just fine, audio exactly as expected except Vegas as oftenly happens drops a couple of frames of audio where the files are joined.

Not to worry I think, I convince VOBMerge to stich them back together. into one big VOB. Open Vegas again and guess what, waveform builds just fine but my audio munching virus is back, not a sound again.

Think I'll have to sleep on this one. Too much excitement today. V9 arrived and I GOT THE BOX :)

Bob.

UlfLaursen wrote on 5/15/2009, 8:17 AM

Hi Bob

I have done this quite often in 7 and 8 with the import from disc, and is has worked fine. I also get splitted files, in my case I think it is splitted in chaptermarks - my sony DVD recorder makes a mark every 5 min. on the disc, and as far as I remember, I get 5 min. files. I have always left the splitted files alone, but it could be interesting to test the 'stiching' next time to se if I got the audio prob too.

But as you put it, it is wierd.

/Ulf

farss wrote on 5/15/2009, 3:31 PM

The audio problem is not coming from the stitching, it's from the mpeg audio in the stream. I've done exactly this before with PCM and ac3 audio no problem. On top of that it happens exact;y the same with the original VOB before it was split.

Good news, workaround found. I opened the original VOB in Sound Forge. It let me play the footage for a few seconds before it too went in Silent Movie mode. However just for giggles I tried Saving As a regular 16/48K wav file and that file is perfect.

If I open the original VOB in Vegas and immediately mute its audio track and add the wav file from SF all is well, goodbye silent movie "virus".

Bob.

farss wrote on 5/16/2009, 1:16 AM

Sorry if this reads like a blog, just wanted to document my journey for the benefit of others.

My method above failed also. After a while of editing even with the mpeg audio track deleted from the project somehow it found it's way back into Vegas's thoughts and killed all audio. Not that one could edit that way but just to see what was going on I rendered a small section and the audio was flatlined.

To finally get this 30minute free job to fly I placed the original VOB onto the T/L, deleted it's audio track and added the previously created wav file from Sound Forge. Visually checked the sync and rendered to the Sony YUV codec in 8 bit. That gave me a clean file to work from. Job is finally out the door.

I really hate those STB DVD recorders. I know it's a cheap and easy way to hand the mourners a DVD of the service but they could have chosen a model that does record PCM audio or even ac3. Just to help image quality they've recorded in EP mode or some such. The 40 min service fitted into a single VOB and the camera's quality looks like something that used to record to VHS-C.

Bob.