[ffmpeg-qsv][avc_encode]encode file bitrate out of range target 10% on iHD driver.

[a]

Summary of the bug:

(real_filezise-ref_filesize)/ref_filesize > 10%

environment

FFMPEG-QSV	CFL	OS: ubuntu 17.04	kernel: 4.15.0
	KBL	OS: ubuntu 16.04	kernel: 4.14.0-rc1
	SKL	OS: ubuntu 16.04	kernel: 4.15.0
			
libva	b6c50dad4d7d14c507108d9f468662e2d7ae1c4d	 https://github.com/01org/libva.git  ( master )
iHD Driver	ed04556a6676fd77ff845508bc54bfc60915450c	 https://github.com/intel/media-driver
libva-utils	9a10ad663349732decd668a426cfc349b0010d1d	 https://github.com/01org/libva-utils.git
Mediasdk	7ea683585f0f84f1bea035a405855312c92c46c0	 https://github.com/Intel-Media-SDK/MediaSDK
FFMPEG	56f68a099cc607658118e00cad30569103ae3751	 https://git.ffmpeg.org/ffmpeg.git

How to reproduce:

1.build env as above lists
2.ffmpeg -hwaccel qsv -init_hw_device qsv=hw -filter_hw_device hw -v verbose -f rawvideo -video_size 3840x2160 -pix_fmt yuv420p -i ./encoderbitstreams//4K_2013_3840_2160_300frames.yuv -an -vf hwupload=extra_hw_frames=64,format=qsv -c:v h264_qsv -g 30 -bf 3 -r 30 -b:v 3M -maxrate:v 3M -preset 4 -vframes 100 -vsync 0 -y ./h264e_cbr_3840x2160_gop30_refdist3_bitrate3M.h264
3. size of h264e_cbr_3840x2160_gop30_refdist3_bitrate3M.h264 =1561474 ,  ref_filesize = 3 * 1024 =3072
4. bitrate_real=1561474*8*30/1024/100=3659.70
5. bitrate_gap = (3659.70-3072)/3072= 19.00% large than 10%

failed case

h264e_cbr_352x288_gop30_refdist3_bitrate100k.h264 on CFL/KBL/SKL
h264e_cbr_3840x2160_gop30_refdist3_bitrate3M.h264 on CFL/KBL/SKL
h264e_cbr_3840x2160_gop30_refdist3_bitrate5M.h264 on SKL
h264e_cbr_720x480_gop30_refdist3_bitrate1M.h264 on CFL/KBL
h264e_cbr_720x480_gop30_refdist3_bitrate2M.h264 on CFL/KBL
h264e_vbr_352x288_gop30_refdist3_bitrate100k.h264 on CFL/KBL/SKL
h264e_vbr_352x288_gop30_refdist3_bitrate200k.h264 on CFL/KBL/SKL
h264e_vbr_720x480_gop30_refdist3_bitrate1M.h264 on CFL/KBL/SKL
h264e_vbr_1280x720_gop30_refdist3_bitrate8M.h264 on CFL/KBL/SKL

yuv file too large to upload

[Carl Eugen Hoyos]

How could this possibly be an issue that can be fixed in FFmpeg?

[Zhong,Li]

3Mbps is a little strict for a 4K video. Especially you are just encoding 100 frames.
Agree with Carl, please make sure it is a ffmpeg issue before you create an issue.