Bitrate setting has no effect on output?

tranglos wrote on 7/6/2010, 4:51 PM

I've been trying out various rendering settings to get the optimal quality / filesize ratio in Vegas 10. What's rather strange is that the bit rate setting and CBR/VBR choice seem to have no effect on the rendered file.

For example, I render the movie using three different settings, all derived from the factory profile "MainConcept MPEG-2, HDV 720p-25p":

(1) the factory profile above, with audio bitrate reduced to 224 kbps, using constant video bitrate of 15 703 000
(2) the same, with video VBR max 5000000, avg 2500000, min 192000, single pass
(3) the same, with video VBR max 10000000, avg 5000000, min 192000, two-pass

No matter what the bitrate, constant, variable, one or two pass, I'm always getting a file of the same exact size, though not the same contents. Why could this be? Shouldn't the file size differ with lower bitrates?

FWIW, for all the profiles I have the "quality" slider set to Max. When I save the settings to a custom profile, Vegas displays my specified bitrate in the info panel, so it seems to accept it.

(Of course I do get different results when using different factory presets, but not when tweaking a specific preset.)

Comments

musicvid10 wrote on 7/6/2010, 9:06 PM

"all derived from the factory profile "MainConcept MPEG-2, HDV 720p-25p"

That is the cause of your problem. HDV is a defined industry standard. It comes in a few basic flavors. Vegas 10 is smart enough to not let you make changes from the standard while maintaining an .m2t extension.

The solution is to start with the Default template, which is .mpg. Then, any changes you make to bitrate or anything else will "stick."

Or, if you wish to use the HDV settings as a starting point for your custom renders, change the Output Type to MPEG-2, and save the template using a new name.

tranglos wrote on 7/7/2010, 5:21 AM

Thanks, musicvid, but that doesn't seem to help.

I start with "Main Concept MPEG-2", pick the default template, select MPEG-2 as output type (instead of HDV) and change aspect ratio to 16:9. This produces mpg files instead of m2t. But still, no matter what bitrate I use, all resulting files have the same exact size (and really the same apparent visual quality when played).

(Also, unlike in the video settings, changing audio bitrate does affect the files as it should.)

This is very strange. At the very least, settings which cannot be changed or which make no sense in context should be disabled in the Custom dialog. There is no indication in the Help files or Vegas knowledge base that what I'm doing is not supposed to work. I've sent a support request to Sony.

Chienworks wrote on 7/7/2010, 8:12 AM

It works in Vegas Pro 9, so maybe it's a bug in Studio 10.

musicvid10 wrote on 7/7/2010, 8:31 AM

Before I posting a response, I always test my suggestions first whenever possible. In this case, I tried all your settings starting with both the HDV and MPEG-2 profiles using the Vegas 10 trial.

My results were that HDV rendering parameters did not change for the reason I stated, and that all the changes took effect as I expected using MPEG-2.

But since you don't know about profile/level settings yet, start with the Default template (that's the actual name of the template!) as I suggested first. Then, when you have achieved results, proceed to the second suggestion, noting the differences, and see what you can learn from it. Good luck.

HDV Template:
General : C:\Users\****\Desktop\Untitled.m2t

Settings #1:
General : C:\Users\****\Desktop\Untitled1.mpg

Settings #2:
General : C:\Users\****\Desktop\Untitled2.mpg

Settings #3:
General : C:\Users\****\Desktop\Untitled3.mpg