Heads up on DVDA issue.

farss wrote on 10/8/2003, 8:51 AM
I've posted this as an issue on the DVDA forum but as it seems to get read by very few these days I'll mention it hear as well.

This only relates to producing silent videos on DVDA. I'm doing a lot of this from 8mm film.

It seems that even though there is no sound to get muxed into the mpeg stream selecting AC3 audio instead of PCM permits you to fit much more video onto the DVD. This doesn't make a whole lot of sense to me buts its more of an annoyance that I wasted quite a few hours re encoding only to discover that the previous encode would have fitted if I'd changed to AC3.

I guess this doesn't affect too many of us, but it could also have an influence on say intro video with no sound or silent animated backgrounds.

Comments

planders wrote on 10/8/2003, 8:58 AM
Sort of makes sense, since PCM is uncompressed and thus even a silent PCM track needs to include every '0'. A silent AC3 track, on the other hand, should compress down to almost nothing. And since sound quality won't be an issue, you can safely set the minimum bitrate to free up every last bit of space for video.
farss wrote on 10/8/2003, 9:36 AM
planders,
you mised the point here, there is no audio track at all, none, zip!

Yet DVDA must still mux in an empty track. I now the mpeg file that goes into DVDA has to contain blank audio frames (an mpeg file that doesn't is a m2v file and DVDA will not work with them).

But what staggered me is that the total of all the created VOB files is much larger than the mpeg file. If I had added audio I'd expect them to roughly total to the same as the total of the mpeg video file and the audio file.
TorS wrote on 10/8/2003, 1:30 PM
Even if he missed the point I think he gave you a good idea. Add a AC3 soundtrack with the lowest possible bitrate.
Tor
planders wrote on 10/8/2003, 1:38 PM
I assume the point I missed is that you're letting the encode happen during the DVDA Prepare DVD process; simple mistake, as I generally prepare my streams in Vegas.

Still, my comment is probably still valid--since the DVD format requires an audio stream, DVDA has to create a blank audio stream. So, selecting AC3 and overriding the default bitrate with a low setting will max out the video capacity of the disc and minimize the wasted space used by the silent audio track.
kentwolf wrote on 10/8/2003, 8:03 PM
For what it's worth:

Adobe Encore DVD will allow you to compile DVDs with absolutely no sound track at all.

Extremely flexible.

Just my $0.02.
farss wrote on 10/8/2003, 8:49 PM
I do the encode within VV, if I'd done it in DVDA I would have imediatley seen that the bitrate was too high to fit on the DVD.

Your suggestion though is probably going to achieve much the same thing as DVDA is doing anyway, muxing in an empty audio stream. As an AC3 stream with nothing in it is much smaller than a PCM stream that would be why the muxed VOB files are much smaller.