QSVEnc AV1 VBR - Bufsize multiplied by 4

I'm encoding AV1 with an Arc A750, vbv-bufsize is being multiplied by 4 so I've had to divide my bufsize setting by 4 to compensate.

--avsync vfr --avsw --crop 0,20,0,20 --codec av1 --output-depth 10 --quality 1 --vbr 6000k --qp-max 64 --qp-min 255 --max-bitrate 9000k --vbv-bufsize 3000k --fallback-rc --la-depth 100 --tune vmaf --gop-len 96 --vpp-edgelevel --colormatrix bt709 --colorprim bt709 --transfer bt709 --colorrange limited --chromaloc auto --audio-stream 1?5.1 --audio-codec 1?ac3:dialnorm=-20 --audio-bitrate 1?448k --audio-samplerate 1?48000 --audio-filter 1?loudnorm=i=-20:lra=18,aresample=out_chlayout=5.1 --metadata clear --video-metadata clear --audio-metadata clear --audio-metadata language=eng --thread-priority all=abovenormal

cop.AUDelimiter value changed off -> auto by driver cop.PicTimingSEI value changed off -> auto by driver cop.SingleSeiNalUnit value changed off -> auto by driver QSVEncC (x64) 7.84 (r3665) by rigaya, Mar 22 2025 11:42:46 (VC 1943/Win) OS Windows 11 x64 (26100) [UTF-8] CPU Info AMD Ryzen 9 3900X 12-Core Processor [4.30GHz] (12C/24T) <DG2> GPU Info Intel Arc A750 Graphics (448EU) 300-2400MHz (32.0.101.6732) Media SDK QuickSyncVideo API v2.14, FF, 1st(d) GPU Async Depth 3 frames Hyper Mode off Buffer Memory d3d11, 123 work buffer Input Info avsw: h264(yv12)->p010 [AVX2], 1920x1080, 24000/1001 fps crop(0,20,0,20) VPP cspconv(p010 -> yv12(16bit)) edgelevel: strength 5.0, threshold 20.0, black 0.0, white 0.0 cspconv(yv12(16bit) -> p010) AVSync vfr Output AV1(yuv420 10bit) main @ Level 4 1920x1040p 1:1 23.976fps (24000/1001fps) avwriter: av1, #1:dca/5.1(side):5.1:loudnorm+aresample -> ac3/5.1/448kbps => matroska Target usage 1 - best Encode Mode Bitrate Mode - VBR Bitrate 6000 kbps Max Bitrate 9000 kbps VBV Bufsize 12000 kb LookaheadDepth 100 Tune Quality vmaf QP Limit min: 64, max: 255 Ref frames 5 frames GopRefDist 8, B-pyramid: on Max GOP Length 96 frames VUI matrix:bt709,colorprim:bt709,transfer:bt709,range:limited,chromaloc:left [40.7%] 56374 frames: 80.04 fps, 6841 kbps, remain 0:17:06, GPU 5%, VD 24%, est out size 4712.8MB

Apr 06 '25 03:04 holmy88

AV1 Bufsize seems to be multiplied by number of temporal layers (which depends on --gop-ref-dist value) by the driver. QSVEnc 7.86 will show the original value in the log.

Apr 16 '25 11:04 rigaya

I’ll close this issue, as the problem should have been already fixed in QSVEnc 7.86.

Aug 31 '25 10:08 rigaya