Comments

riredale wrote on 10/23/2004, 9:38 AM
Why not do a couple of experiments to find out? Some people on this board say you should never go above 7Mb/sec; the official spec says anything under 9.8 is legal, but others say that DVD-R (burned) disks are not as easy to read as pressed disks, so the player sometimes has to re-read, which causes problems, etc.

In my own experience I found that an average bitrate of around 8Mb/sec gave excellent image quality and never caused a player to choke.

Your 2-channel AC-3 audio will be about .2Mb/sec, so if you shoot for 8 as your target, your video rate should be 7.8Mb/sec. But it's really not that critical.
John_Cline wrote on 10/23/2004, 9:44 AM
The total can't exceed about 9.8 megabits/sec. On short videos, I normally use 8 Mbits CBR for the video and 192k for the AC3 audio. Some MPEG2 encoders will occasionally "spike" above the the set bitrate, so it's a good idea to leave a little "wiggle room", hence the 8 Mbits + 192 Kbits. I suppose you may be able to 9 Mbits + 192k AC3 and still leave enough headroom for spikes. I use ProCoder to make MPEG2 files and it doesn't spike, I'm not sure about the MainConcept encoder in Vegas.

John
JHendrix wrote on 10/23/2004, 6:36 PM
Isnt 192 rather low for audio?
Liam_Vegas wrote on 10/23/2004, 6:57 PM
192 for AC3 is perfectly adequate. The Dolby AC3 is the critical thing. If you are using the PCM format - that would be a different matter!