ffmpeg - CRF/CQP 与 2pass 不兼容。 FFmpeg错误

Question

这是我的命令:

..\ffmpeg -y -i "D:\FFMPEG\ffmpeg-20200129-de1b2aa-win64-static\bin\test\aa_start_with_BAGAN.mp4" -c:v libx264 -preset ultrafast -maxrate 3000k -bufsize 6000k -g 50 -c:a aac -b:a 128k -ac 2 -ar 44100 -an -pass 1 -f mp4 NUL   && ..\ffmpeg -i "D:\FFMPEG\ffmpeg-20200129-de1b2aa-win64-static\bin\test\aa_start_with_BAGAN.mp4" -c:v libx264 -s 1280x720 -preset ultrafast -maxrate 500k -bufsize 1000k -vf "scale=1280:-1,format=yuv420p" -g 50 -c:a aac -b:a 128k -ac 2 -ar 44100 -an -pass 2 aa_start_with_BAGAN.mp4_ultrafast_500.mp4

在输出中我得到 CRF/CQP is incompatible with 2pass，但我根本没有在命令中使用 cfr/-q 选项，为什么会出现此错误？ 添加 FFMpeg 的完整元数据，也许有人可以帮我解决这个问题？ (-g 50 因为根据文档默认的 fps 是 25)

`ffmpeg version git-2020-01-29-de1b2aa Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.2.1 (GCC) 20200122
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 38.100 / 56. 38.100
  libavcodec     58. 67.100 / 58. 67.100
  libavformat    58. 36.100 / 58. 36.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 71.100 /  7. 71.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'D:\FFMPEG\ffmpeg-20200129-de1b2aa-win64-static\bin\test\aa_start_with_BAGAN.mp4':
  Metadata:
    major_brand     : M4V
    minor_version   : 1
    compatible_brands: M4V mp42isom
    creation_time   : 2018-04-24T18:21:09.000000Z
  Duration: 00:35:54.00, start: 0.000000, bitrate: 1057 kb/s
    Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv), 640x480 [SAR 1:1 DAR 4:3], 929 kb/s, 25 fps, 25 tbr, 50k tbn, 50 tbc (default)
    Metadata:
      creation_time   : 2018-04-24T18:21:09.000000Z
      handler_name    : Mainconcept MP4 Video Media Handler
      encoder         : AVC Coding
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
    Metadata:
      creation_time   : 2018-04-24T18:21:09.000000Z
      handler_name    : Mainconcept MP4 Sound Media Handler
Codec AVOption b (set bitrate (in bits/s)) specified for output file #0 (NUL) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0000024ec2de0f80] using SAR=1/1
[libx264 @ 0000024ec2de0f80] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0000024ec2de0f80] profile Constrained Baseline, level 3.0, 4:2:0, 8-bit
[libx264 @ 0000024ec2de0f80] 264 - core 159 - H.264/MPEG-4 AVC codec - Copyleft 2003-2019 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=50 keyint_min=5 scenecut=0 intra_refresh=0 rc_lookahead=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=3000 vbv_bufsize=6000 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=0
Output #0, mp4, to 'NUL':
  Metadata:
    major_brand     : M4V
    minor_version   : 1
    compatible_brands: M4V mp42isom
    encoder         : Lavf58.36.100
    Stream #0:0(eng): Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=-1--1, 25 fps, 12800 tbn, 25 tbc (default)
    Metadata:
      creation_time   : 2018-04-24T18:21:09.000000Z
      handler_name    : Mainconcept MP4 Video Media Handler
      encoder         : Lavc58.67.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 3000000/0/0 buffer size: 6000000 vbv_delay: N/A
frame=53849 fps=999 q=-1.0 Lsize=  496489kB time=00:35:53.92 bitrate=1888.3kbits/s speed=39.9x
video:496266kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.044919%
[libx264 @ 0000024ec2de0f80] frame I:1077  Avg QP:20.39  size: 38800
[libx264 @ 0000024ec2de0f80] frame P:52772 Avg QP:23.39  size:  8838
[libx264 @ 0000024ec2de0f80] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0000024ec2de0f80] mb P  I16..4:  8.4%  0.0%  0.0%  P16..4: 51.8%  0.0%  0.0%  0.0%  0.0%    skip:39.8%
[libx264 @ 0000024ec2de0f80] coded y,uvDC,uvAC intra: 44.8% 54.5% 18.3% inter: 30.2% 22.0% 2.0%
[libx264 @ 0000024ec2de0f80] i16 v,h,dc,p: 39% 25% 16% 19%
[libx264 @ 0000024ec2de0f80] i8c dc,h,v,p: 35% 23% 24% 17%
[libx264 @ 0000024ec2de0f80] kb/s:1887.41
ffmpeg version git-2020-01-29-de1b2aa Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.2.1 (GCC) 20200122
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 38.100 / 56. 38.100
  libavcodec     58. 67.100 / 58. 67.100
  libavformat    58. 36.100 / 58. 36.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 71.100 /  7. 71.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'D:\FFMPEG\ffmpeg-20200129-de1b2aa-win64-static\bin\test\aa_start_with_BAGAN.mp4':
  Metadata:
    major_brand     : M4V
    minor_version   : 1
    compatible_brands: M4V mp42isom
    creation_time   : 2018-04-24T18:21:09.000000Z
  Duration: 00:35:54.00, start: 0.000000, bitrate: 1057 kb/s
    Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv), 640x480 [SAR 1:1 DAR 4:3], 929 kb/s, 25 fps, 25 tbr, 50k tbn, 50 tbc (default)
    Metadata:
      creation_time   : 2018-04-24T18:21:09.000000Z
      handler_name    : Mainconcept MP4 Video Media Handler
      encoder         : AVC Coding
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
    Metadata:
      creation_time   : 2018-04-24T18:21:09.000000Z
      handler_name    : Mainconcept MP4 Sound Media Handler
Codec AVOption b (set bitrate (in bits/s)) specified for output file #0 (aa_start_with_BAGAN.mp4_ultrafast_500.mp4) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0000013691fbda00] using SAR=3/4
[libx264 @ 0000013691fbda00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0000013691fbda00] CRF/CQP is incompatible with 2pass.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!`

Answer 1

如果不设置目标码率-b:v，ffmpeg会默认为CRF模式。 maxrate 和 bufsize 设置 VBV 约束，可用于比特率和 CRF 模式。

对于正确的 2 遍编码，所有过滤器和编码参数在两次遍历中都应该相同。