Setting mpeg 2 render bitrate to 7k produces 7.7k

TonyP wrote on 8/31/2012, 7:57 PM
I recently upgraded to Vegas Pro 10 (I'm on XP where 11 is not available) and went to render a 1 hour 22 minute project to MPEG2 for DVD and set the maximum and average bitrates to 7000 and the lowest to 4200, VBR 2 pass but the resulting file was 7702 and too big to fit on the DVD. Am I doing something stupid with my settings?

Comments

rs170a wrote on 8/31/2012, 8:05 PM
Your bitrate settings are fine (I'd bump the max up to 8500 but that's just me).
If you rendered your audio as a WAV file, that would do it.
Use AC-3 instead.
If that file size was reported by DVDA, ignore it as it has a long history of incorrectly reporting file sizes.
It happens to me at least once a week and I know that my total file size is under the limit.
When you get the warning, ignore it and DVDA will continue on as expected.

Mike
Former user wrote on 8/31/2012, 8:06 PM
Not for sure, but if you set the average rate to 7000, in order for it to average that rate, it has to go over it sometimes.

Set your average lower.

Dave T2
musicvid10 wrote on 8/31/2012, 9:12 PM
http://www.videohelp.com/calc.htm
It has never gone over available disk space for me.
TonyP wrote on 8/31/2012, 11:08 PM
Thanks guys,

I do use the videohelp bitrate calculator (it's where I got the 7k figure) but what Vegas produced was definitely too big - the file shows as 4.9GB in Explorer - and video info programs show the bitrate to be 7.7K (DVDA shows it to be 8k but I am used to it showing higher than reality),

Either way, the only way I could get it to fit on a DVD was to recompress it in DVDA, which I'd like to avoid by getting my bitrate settings right and having Vegas keep the bitrate within what I set.

I think you're right about the audio possibly adding to the file size because I used to use AC3 as a separate file but in this instance I included the audio in the MPEG stream. Not sure why this would affect the bitrate though.
musicvid10 wrote on 8/31/2012, 11:11 PM
"but in this instance I included the audio in the MPEG stream. "
Don't do that.
Chienworks wrote on 9/1/2012, 8:19 AM
If you have the average and max set to the same then you really should just use constant at that rate. When they are the same you're not giving the VBR encoder any room to work with, so i'm not surprised it messed up.
TonyP wrote on 9/1/2012, 8:20 AM
Thank you very much, everyone, it's working fine now :)
riredale wrote on 9/1/2012, 12:57 PM
The bitrate calculator is okay, but I've always used a trivial calculator:

Video+audio bitrate total = 600 / minutes.

That's it. If you have 100 minutes of video, the bitrate needs to be 6Mb/sec. Subtract .2 for the ac3 audio, you have 5.8, so set your average bitrate at that. Then I use max 9 and min 1. Done.
rs170a wrote on 9/1/2012, 2:40 PM
http://www.johncline.com/bitcalc110.zip has been my go to calculator for a long time and it's never let me down.

Mike
John_Cline wrote on 9/1/2012, 4:43 PM
Setting the average and maximum bit rates to the same value completely defeats the purpose of doing two-pass rendering.
John_Cline wrote on 9/1/2012, 4:47 PM
Setting the average and maximum bit rates to the same value completely defeats the purpose of doing two-pass rendering. Just set it to 6,960,000 bps CBR and be done with it. It will also take half as long to render. VBR is useful when you're trying to cram 2-3 hours on a disc and have to use a low average bit rate but want to throw some extra bits at the high motion stuff when it need it. That's what the maximum bitrate setting is for.