Problem with rendered ac3

Maverick wrote on 10/24/2007, 5:06 PM

I have just attempted to render an ac3 file after rendering the project to DVD mpg2.

I did exactly the same as yesterday yet the ac3 does not load properly into DVDAPro.

The ac3 plays fine in 7 Showtime and shows the full length but when dragged to DVDAPro it shows just 24 seconds 23 frames (PAL) out of a total of 3 mins 40 secs and 6 frames with message in the Audio timeline: 'Audio peaks not avialable.

I have re-rendered several times each with the same result. I am using the default Dolby Digial AC-3 Pro template with no changes.

Can anyone shed some light or point me in the right direction of where to solve this?

Cheers

Comments

daves2 wrote on 10/24/2007, 6:28 PM

just a bit of speculation but it sounds like there's a glitch in the encoding, either in the source material or the output (yes, I know that's obvious).

did you try rendering as a WAV file in vegas and then letting DVDA encode to AC3? (set your paramers for the DVDA project for AC3 audio). Perhaps if there is a glitch in your vegas projec,t letting it encode to WAV will fix it . I would think the DVDA AC3 encoder is the exact same as vegas, so if its something in your source that the encoder can't deal with, it may show up there too.

but, if you haven't tried that, may be worth a shot.

TGS wrote on 10/24/2007, 8:05 PM

Be sure, you destroy the old ac3 file, before rendering a new one. That means, EMPTY THE TRASH BIN 1st. If the file name is the same as it was, every time you render, it may just drag the bad one back in as a new render.
I don't know what you mean by "It plays fine in 7 showtime" . You should be able to play it in DVD-A, even without the mpg2
another thing to check for might be any peak in your timeline that goes above 0 dB, before rendering to ac3.
Are you using Vegas to make your ac3s?

Maverick wrote on 10/25/2007, 5:14 AM

Thanks for the replies.

@ daves2:

I have also rendered to MPEG2 DVD PAL (combined A & V) and all appears fine when loaded into DVDA.

I have also rendered to wav and that, too, loaded fine into DVDA.

@TGS
Yes,I always destroy the old ac3 files before re-rendering and I am using Vegas8Pro.

I meant it plays in Nero 7 Showtime without problems.

A system reboot still caused the same problems but I re-rendered to ac3 again but this time I set RF Mode Profile to None and it loaded to DVDA without problems (now same length as corresponding mpg2 file).

TBH I am not sure what RF Mode Profile does but I remember reading somewhere that it can be set to None for improved audio dynamics?

Vegas Help file suggests that PCM is uncompressed offering higher quality and can be used unless 5.1 surround is being used.

As my project does not use 5.1 maybe I am better off rendering to PCM but I can't find that option. Is that liable to appear suddenly as per my other post regarding EDL or is it a simple matter of just selecting PCM in the DVDA Project Properties?

Cheers

Stuart Robinson wrote on 10/25/2007, 5:32 PM

>As my project does not use 5.1 maybe I am better off rendering to PCM but I can't find that option.<

PCM is stored as .WAV on a PC, so that's the option you're looking for. But you're not going to be better off, a 2-channel PCM soundtrack soaks up about seven times the amount of bandwidth as 192kb/s Dolby Digital, so you'll have to reduce the video data rate accordingly.