media-autobuild_suite编译FFmpeg编码H265时Mediainfo参数异常

故障表现 #

使用media-autobuild_suite编译的最新版FFmpeg批量将视频转码为H265格式时，转码完成后用Mediainfo查看输出文件，Writing library和Encoding settings两项参数显示错误，与实际配置的x265编码参数不符，反而和源AVC视频的x264编码参数一致，旧版本FFmpeg无该问题。

环境信息 #

所用FFmpeg版本 #

ffmpeg version N-103367-g5ddb4b6a1b-g88b3e31562+1 Copyright (c) 2000-2021 the FFmpeg developers
built with gcc 10.3.0 (Rev5, Built by MSYS2 project)
configuration:  --pkg-config=pkgconf --cc='ccache gcc' --cxx='ccache g++' --ld='ccache g++' --disable-autodetect --enable-amf --enable-bzlib --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-iconv --enable-lzma --enable-nvenc --enable-schannel --enable-zlib --enable-sdl2 --enable-ffnvcodec --enable-nvdec --enable-cuda-llvm --enable-gmp --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libdav1d --enable-libaom --disable-debug --enable-libfdk-aac --extra-libs=-liconv --enable-gpl --enable-version3 --enable-nonfree
libavutil      57.  4.101 / 57.  4.101
libavcodec     59.  5.101 / 59.  5.101
libavformat    59.  4.102 / 59.  4.102
libavdevice    59.  0.101 / 59.  0.101
libavfilter     8.  3.100 /  8.  3.100
libswscale      6.  0.100 /  6.  0.100
libswresample   4.  0.100 /  4.  0.100
libpostproc    56.  0.100 / 56.  0.100

转码命令 #

ffmpeg -y -hide_banner -loglevel error -stats -hwaccel dxva2 -i "input.mkv" -c:v libx265 -vsync cfr -pix_fmt yuv420p10le -preset fast -tune animation -x265-params ctu=32:min-cu-size=8:max-tu-size=16:tu-intra-depth=2:tu-inter-depth=2:me=1:subme=3:merange=44:max-merge=2:keyint=250:min-keyint=23:rc-lookahead=60:lookahead-slices=6:bframes=6:bframe-bias=0:b-adapt=2:ref=6:limit-refs=3:limit-tu=1:aq-mode=3:aq-strength=0.6:rd=3:psy-rd=1.00:psy-rdoq=1.50:rdoq-level=1:deblock=-1,-1:crf=21.0:qblur=0.50:qcomp=0.60:qpmin=0:qpmax=51:frame-threads=1:strong-intra-smoothing=1:no-lossless=1:no-cu-lossless=1:constrained-intra=1:no-fast-intra=1:no-open-gop=1:no-temporal-layers=1:no-limit-modes=1:weightp=1:no-weightb=1:no-analyze-src-pics=1:no-rd-refine=1:signhide=1:sao=1:no-sao-non-deblock=1:b-pyramid=1:no-cutree=1:no-intra-refresh=1:no-amp=1:temporal-mvp=1:no-early-skip=1:no-tskip=1:no-tskip-fast=1:no-deblock=1:no-b-intra=1:no-splitrd-skip=1:no-strict-cbr=1:no-rc-grain=1:no-const-vbv=1:no-opt-qp-pps=1:no-opt-ref-list-length-pps=1:no-multi-pass-opt-rps=1:no-opt-cu-delta-qp=1:no-hdr=1:no-hdr-opt=1:no-dhdr10-opt=1:no-idr-recovery-sei=1:no-limit-sao=1:no-lowpass-dct=1:no-dynamic-refine=1:no-single-sei=1 -c:a libfdk_aac -vf "fps=fps=29.970,setdar=16/9,scale=960:540:flags=lanczos" -map 0:v:? -map 0:a:? -map_metadata:g -1 -map_chapters 0 "output.mkv"

对比参数 #

源视频参数 #

Video
ID                          : 1
Format                      : AVC
Format/Info                 : Advanced Video Codec
Format profile              : High@L3
Format settings             : CABAC / 5 Ref Frames
Format settings, CABAC      : Yes
Format settings, Reference  : 5 frames
Codec ID                    : V_MPEG4/ISO/AVC
Bit rate                    : 1 595 kb/s
Nominal bit rate            : 2 030 kb/s
Width                       : 720 pixels
Height                      : 480 pixels
Display aspect ratio        : 16:9
Original display aspect rat : 3:2
Frame rate mode             : Variable
Original frame rate         : 29.970 FPS
Color space                 : YUV
Chroma subsampling          : 4:2:0
Bit depth                   : 8 bits
Scan type                   : Progressive
Bits/(Pixel*Frame)          : 0.196
Writing library             : x264 core 66 r1115M 11863ac
Encoding settings           : cabac=1 / ref=5 / deblock=1:1:1 / analyse=0x3:0x133 / me=esa / subme=7 / psy_rd=1.0:0.0 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=2 / deadzone=21,11 / chroma_qp_offset=-2 / threads=1 / nr=0 / decimate=0 / mbaff=0 / bframes=1 / b_pyramid=0 / b_adapt=1 / b_bias=0 / direct=3 / wpredb=1 / keyint=250 / keyint_min=25 / scenecut=40 / rc=2pass / bitrate=2030 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / pb_ratio=1.30 / aq=1:1.00
Default                     : Yes
Forced                      : No

异常输出参数 #

Video
ID                          : 1
Format                      : HEVC
Format/Info                 : High Efficiency Video Coding
Format profile              : Main 10@L3.1@Main
Codec ID                    : V_MPEGH/ISO/HEVC
Duration                    : 23 min 29 s
Width                       : 960 pixels
Height                      : 540 pixels
Display aspect ratio        : 16:9
Frame rate mode             : Constant
Frame rate                  : 29.970 (29970/1000) FPS
Color space                 : YUV
Chroma subsampling          : 4:2:0
Bit depth                   : 10 bits
Writing library             : Lavc59.5.100 libx265
Encoding settings           : cabac=1 / ref=5 / deblock=1:1:1 / analyse=0x3:0x133 / me=esa / subme=7 / psy_rd=1.0:0.0 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / cqm=2 / deadzone=21,11 / chroma_qp_offset=-2 / threads=1 / nr=0 / decimate=0 / mbaff=0 / bframes=1 / b_pyramid=0 / b_adapt=1 / b_bias=0 / direct=3 / wpredb=1 / keyint=250 / keyint_min=25 / scenecut=40 / rc=2pass / bitrate=2030 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / pb_ratio=1.30 / aq=1:1.00
Default                     : Yes
Forced                      : No
Color range                 : Limited

预期输出参数 #

Video
ID                          : 1
Format                      : HEVC
Format/Info                 : High Efficiency Video Coding
Format profile              : Main 10@L3.1@Main
Codec ID                    : V_MPEGH/ISO/HEVC
Duration                    : 24 min 37 s
Bit rate                    : 833 kb/s
Width                       : 960 pixels
Height                      : 720 pixels
Display aspect ratio        : 4:3
Frame rate mode             : Constant
Frame rate                  : 23.976 (23976/1000) FPS
Color space                 : YUV
Chroma subsampling          : 4:2:0
Bit depth                   : 10 bits
Bits/(Pixel*Frame)          : 0.050
Stream size                 : 147 MiB
Title                       : HEVC
Writing library             : x265 3.4+28-419182243:[Windows][GCC 10.2.0][64 bit] 10bit
Encoding settings           : cpuid=1111039 / frame-threads=3 / numa-pools=12 / wpp / no-pmode / no-pme / no-psnr / no-ssim / log-level=2 / input-csp=1 / input-res=960x720 / interlace=0 / total-frames=0 / level-idc=0 / high-tier=1 / uhd-bd=0 / ref=5 / no-allow-non-conformance / no-repeat-headers / annexb / no-aud / no-hrd / info / hash=0 / no-temporal-layers / no-open-gop / min-keyint=1 / keyint=360 / gop-lookahead=0 / bframes=4 / b-adapt=2 / b-pyramid / bframe-bias=0 / rc-lookahead=20 / lookahead-slices=4 / scenecut=40 / hist-scenecut=0 / radl=0 / no-splice / no-intra-refresh / ctu=64 / min-cu-size=8 / no-rect / no-amp / max-tu-size=32 / tu-inter-depth=1 / tu-intra-depth=1 / limit-tu=0 / rdoq-level=0 / dynamic-rd=0.00 / no-ssim-rd / signhide / no-tskip / nr-intra=0 / nr-inter=0 / no-constrained-intra / strong-intra-smoothing / max-merge=2 / limit-refs=3 / no-limit-modes / me=1 / subme=3 / merange=16 / temporal-mvp / no-frame-dup / no-hme / weightp / no-weightb / no-analyze-src-pics / no-deblock / sao / no-sao-non-deblock / rd=3 / selective-sao=4 / no-early-skip / rskip / no-fast-intra / no-tskip-fast / no-cu-lossless / no-b-intra / no-splitrd-skip / rdpenalty=0 / psy-rd=0.20 / psy-rdoq=0.00 / no-rd-refine / no-lossless / cbqpoffs=0 / crqpoffs=0 / rc=crf / crf=26.0 / qcomp=0.60 / qpstep=4 / stats-write=0 / stats-read=0 / ipratio=1.40 / pbratio=1.00 / aq-mode=0 / aq-strength=0.00 / no-cutree / zone-count=0 / no-strict-cbr / qg-size=64 / no-rc-grain / qpmax=51 / qpmin=0 / no-const-vbv / sar=1 / overscan=0 / videoformat=5 / range=0 / colorprim=2 / transfer=2 / colormatrix=2 / chromaloc=0 / display-window=0 / cll=0,0 / min-luma=0 / max-luma=1023 / log2-max-poc-lsb=8 / vui-timing-info / vui-hrd-info / slices=1 / no-opt-qp-pps / no-opt-ref-list-length-pps / no-multi-pass-opt-rps / scenecut-bias=0.05 / hist-threshold=0.03 / no-opt-cu-delta-qp / no-aq-motion / no-hdr10 / no-hdr10-opt / no-dhdr10-opt / no-idr-recovery-sei / analysis-reuse-level=0 / analysis-save-reuse-level=0 / analysis-load-reuse-level=0 / scale-factor=0 / refine-intra=0 / refine-inter=0 / refine-mv=1 / refine-ctu-distortion=0 / no-limit-sao / ctu-info=0 / no-lowpass-dct / refine-analysis-type=0 / copy-pic=1 / max-ausize-factor=1.0 / no-dynamic-refine / no-single-sei / no-hevc-aq / no-svt / no-field / qp-adaptation-range=1.00 / no-scenecut-aware-qpconformance-window-offsets / right=0 / bottom=0 / decoder-max-rate=0 / no-vbv-live-multi-pass
Language                    : English
Default                     : Yes
Forced                      : No
Color range                 : Limited

已执行测试 #

• 使用官网下载的最简版FFmpeg、简化为ffmpeg -i "input.mkv" -c:v libx265 "output.mkv"命令测试，问题仍复现
• 官网FFmpeg 4.4 "Rao"版本运行正常
• media-autobuild_suite编译的轻量版、完整版FFmpeg均存在该问题

根本原因 #

该问题属于FFmpeg 5.0开发分支版本的Matroska封装器元数据继承bug：

1. 你使用的N-103367版本属于FFmpeg 4.4之后的5.0开发分支，该版本对MKV封装的元数据继承逻辑做了改动，默认会继承源文件视频流的私有元数据（包括Writing library、Encoding settings），而libx265生成的新元数据没有正确覆盖旧的继承值
2. media-autobuild_suite的编译配置默认开启了MKV元数据全继承的编译选项，进一步触发了该bug；官网4.4正式版没有引入该逻辑改动，因此运行正常

修复方案 #

在你的转码命令中加入-map_metadata:s:v -1参数，明确禁止继承源文件的视频流元数据，即可让libx265生成的编码参数正确写入输出文件。修改后的命令核心部分示例：

ffmpeg -i "input.mkv" -c:v libx265 [其他编码参数] -map_metadata:g -1 -map_metadata:s:v -1 -map_chapters 0 "output.mkv"

内容的提问来源于stack exchange，提问作者Foong