When to set as VBR and CBR?

[Jeff_NJ]

I was playing around in Vegas with using custom settings based on the bitrate calculator. One question came up. What type of projects require you to use VBR and which require CBR? Is there a safer one to use in general? Thanks.

Jeff

[Baldrick]

What are you making? DVD?

[Jeff_NJ]

Yep, just converted a school play from vhs, ripped to avi, did some minor editing in Vegas and am ready to render. I'll then import into dvd architect.

Jeff

[lordsmurf]

You cannot "rip" VHS.

[jagabo]

If you want to put much more than 60 minutes of full D1 video on a single layer DVD use VBR. Othewise use CBR and a high bitrate, ~8000 to 9000 kbps for the video.

[Jeff_NJ]

Sorry, by rip I meant I converted my vhs tape to a dvd using a dvd recorder. Then ripped that to my pc and imported into vegas.

Thanks for the info guys.

Jeff

[tinker]

VBR is good to use if your video has fast motion in it. In that case good encoder will use higher bitrate, where for no motion will use low bitrate so end product is better.
For VHS tapes it will not make that much difference, because original video is not that good to begin with.

[Jeff_NJ]

Ah, that answers my question..

So if there is movement involved, go with VBR? If the object is stationary, go with CBR? Thanks.

Jeff

[edDV]

Ah, that answers my question..

So if there is movement involved, go with VBR? If the object is stationary, go with CBR? Thanks.

Jeff

CBR at high bit rates get you 60-75 min (e.g. 75 min @ 8500Kb/s with 224Kb/s audio). Use VBR when you want longer recording times.

VBR gets additional compression by reducing bitrate in areas with low motion. Unfortuately, high noise levels from sources like VHS may mask low motion. If the VBR motion detctor fails to find low motion areas due to noise, it just increases in frame compression degrading the picture quality. This is why noise reduction filters help encoders in VBR mode produce better results.

CBR is recommended for hand held camcorder video where pixels are always in motion.

[Jeff_NJ]

Thanks Ed. Appreciate the info.

Jeff