Total audio bitrate highlighted in 'red'?

paige wrote on 8/13/2008, 12:14 AM

Hi all,
I have a question about the Optimize DVD option when preparing a DVD,

Both the video and audio have a 'tick' so they won't be re-rendered. But, the total audio bitrate is listed at 0.192 and highlighted in red. Is this a warning message that the bitrate is somehow incorrect?

I have rendered the video as mpg2, and the audio as ac3 using the stereo DVD template in Vegas.

The project is only 10mins long - so I just want the best audio quality possible.

If anyone could help, that would be great,
Thank you
Paige

Comments

owlsroost wrote on 8/14/2008, 1:47 AM

It should be fine - on DVD the 'standard' bitrate for stereo AC3 is 192kbit/s (0.192Mbit/s), 448kbit/s for 5.1 surround AC3.

You should not exceed 448kbit/s for AC3 on DVD - otherwise the DVD might not play properly on all players.

Tony

paige wrote on 8/14/2008, 2:39 AM

Thank you Tony,
I appreciate your response. I have always used the standard template in vegas "stereo DVD' and have only just noticed the bitrate in DVDA highlighted in red - just wondered if I had done something wrong somewhere!

Whilst searching this forum on this subject, I noticed that some do recommend that you should render as a wav file for DVDA to render, then others disagree, and render out of vegas as ac3 (as I have been doing).

Whlst on the render subject - I always render the video portion as mpg2 (PAL), and use a constant bitrate of 7,000,000 (another subject that causes a bit of confusion to me!). Since most of my projects are only 10 to 15 mins long, disc space isn't an issue, would you say a CBR of 7 is too conservative to obtain both the best quality picture, and, play on the majority of DVD players?

Thanks again
Paige

johnmeyer wrote on 8/14/2008, 8:46 AM

mpeg.org

(Document describing DVD spec and maximum bitrates)

Many people seem concerned about high bitrates making a DVD unplayable in some DVD players. According to the official spec referenced above, all DVD players must be able to sustain almost 10,000,000 bps.

You will find many posts warning about doing CBR at 8,000,000, but you will also find many people who claim to do this all the time with no problem. My recommendation is that you use single-pass VBR at an average of between 7,000,000 and 7,500,000. The VBR should give you marginally better quality than CBR (probably not noticeable). Don't change the minimum and maximum bitrates.

Two-pass VBR is only useful when trying to cram more than and hour and a half of video onto a single-side, single-layer DVD. IMHO, it is pretty much a waste of time until you get to bitrates lower than 6,000,000.

paige wrote on 8/14/2008, 5:43 PM

Thanks John,
I'll start using the VBR with specs as you described, makes perfect sense.
I've never noticed the 2-pass check box before, not even sure what that is, but I'll do some researching. I think it will help if I can understand the rendering process itself.
Thanks again
Paige