CBR or VBR for video use online?

[Les Grossman]

I understand where it would matter for a DVD, but how about the net?

[TheSenator]

I use VBR with 2 passes....

[BobG]

From what I've read, you should always use CBR for video use online, which is what I do. VBR is harder to control file sizes.

Constant bit rate (CBR) encoding persists the set data rate to your setting over the whole video clip. Use CBR only if your clip contains a similar motion level across the entire duration. CBR is most commonly used for streaming video content using the Flash Media Server (rtmp)

Variable bit rate (VBR) encoding adjusts the data rate down and to the upper limit you set, based on the data required by the compressor. VBR takes longer to encode but produces the most favorable results. VBR is most commonly used for http delivery if video content (http progressive)

http://help.encoding.com/idx.php/4/0...-encoding.html

[BobG]

http://en.wikipedia.org/wiki/Variable_bitrate

[JarvisEncoding]

Originally Posted by BobG

From what I've read, you should always use CBR for video use online, which is what I do. VBR is harder to control file sizes.

Constant bit rate (CBR) encoding persists the set data rate to your setting over the whole video clip. Use CBR only if your clip contains a similar motion level across the entire duration. CBR is most commonly used for streaming video content using the Flash Media Server (rtmp)

Variable bit rate (VBR) encoding adjusts the data rate down and to the upper limit you set, based on the data required by the compressor. VBR takes longer to encode but produces the most favorable results. VBR is most commonly used for http delivery if video content (http progressive)

http://help.encoding.com/idx.php/4/0...-encoding.html

Agreed! Perfect answer!

[rowan]

I thought the whole idea of VBR is that it averages out, using extra space for high bandwidth frames and compensating by using less elsewhere for more compressible frames. The encoder I use allows you to specify an average bitrate, and also as an option to pad out any regions that compress extremely well and would cause the average bitrate to drop significantly (important for media which may have a minimum output rate such as a DVD disc). If you tell it to do 500kbps VBR then the output file size will be very close to that of 500kbps CBR.

Even the text that BobG quoted "against" VBR says that it produces the most favourable results.

[rowan]

Originally Posted by rowan

If you tell it to do 500kbps VBR then the output file size will be very close to that of 500kbps CBR.

Should mention that this is 2 pass so it knows which sections to give or take bandwidth from on the second pass.

Single pass VBR is called Constant Quality in my encoder, which basically compresses each frame to a specific size/quality without worrying about average bandwidth.