What's best for 1 pass CBR encoding: CRF+VBV or 1pass+VBV

[Manaka]

I'm working on some CBR encodes for streaming. First I used CRF with VBV , overall PQ looks good except some I frames look horrible(there's no VBV underflow). 1 pass VBV cure the I frames problem but overall PQ doesn't look good compare to CRF


avs2yuv source.avs -o - | start /b /low x264 --demuxer y4m --crf 1 --sar 64:45 --profile main --level 3.2 --ref 4 --bframes 2 --deblock -1:-1 --aq-strength 0.8 --vbv-bufsize 320 --vbv-maxrate 1600 --direct auto --no-mbtree --partitions p8x8,b8x8,i8x8,i4x4 --keyint 100 --no-fast-pskip --no-dct-decimate --subme 8 --trellis 2 --psy-rd 1.0:0.0 --me umh --b-adapt 2 --output "crf.mkv" - 2> x264log.log



avs2yuv source.avs -o - | start /b /low x264 --demuxer y4m --bitrate 1600 --sar 64:45 --profile main --level 3.2 --ref 4 --bframes 2 --deblock -1:-1 --aq-strength 0.8 --vbv-bufsize 320 --vbv-maxrate 1600 --direct auto --no-mbtree --partitions p8x8,b8x8,i8x8,i4x4 --keyint 100 --no-fast-pskip --no-dct-decimate --subme 8 --trellis 2 --psy-rd 1.0:0.0 --me umh --b-adapt 2 --output "1pass.mkv" - 2> x264log.log


Any suggestions ?

[Dark Shikari]

Why is your VBV bufer size so incredibly low? It's no wonder I-frames look horrible, the buffer isn't large enough to contain them.

[Manaka]

I had to use low vbvbufsize to prevent bitrate peak too high, since I want to stream my encode at 2mbps (video +audio) via rtsp protocol

[Dark Shikari]

I had to use low vbvbufsize to prevent bitrate peak too highThis phrase demonstrates you don't know what a VBV is or how it works. The "peak bitrate" does not depend on the bufsize unless you're measuring the peak bitrate without a proper buffer model.

You can't meaningfully use I-frames with such a small bufsize.

[Manaka]

I see , thanks for your info.

BTW what's vbvbufsize would you recommend in my situation? Same as the vbv maxrate?