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View Full Version : Can't achieve decent CBR


leoenc
21st April 2007, 17:11
Hi everyone,

I have read the discussions with akupenguin regarding how to achieve CBR.
The only way I can generate a stream that does not peak over the specified bitrate, is when using a VBV bufsize of the same bitrate.
However, this causes ugly "artifact flashes" from time to time, making the video unacceptable.
If VBV bufsize is set to 0, the artifact flashes are gone, but the stream peaks way above the specified bit rate.

Below is the generated command line from MeGUI. Can anyone help?

--bitrate 2000 --level 3 --keyint 40 --ref 3 --mixed-refs --bframes 3 --b-rdo --bime --weightb --subme 6 --trellis 1 --analyse p8x8,b8x8,i4x4 --qpmin 1 --vbv-bufsize 2000 --vbv-maxrate 2000 --ratetol 0.1 --threads auto --thread-input --progress --no-psnr --no-ssim --output "E:\test.264" "E:\test.avs"

leoenc
21st April 2007, 19:19
When using greater numbers than 2000kbps in VBV bufsize, the artifacts are gone, but I can't just put any number I like there, for streaming reasons.
Actually, I found out that entering any number in VBV bufsize keeps the stream below the specified bit rate. Why is that? Isn't this the purpose of VBV maxrate?