ffmpeg filter_complex concat 永远不会完成

Question

我正在尝试连接 mp4文件合并为一个文件。我正在尝试使用 concat出于与此问题无关的原因直接过滤(因此 -i list.txt 不是有效的解决方案)。所有相关视频文件的长度都在 4 到 20 分钟之间。
我正在执行的操作:

% ffmpeg -i f01.mp4 -i f02.mp4 -filter_complex "[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1[v][a]" -map "[v]" -map "[a]" output.mp4

这是我从 FFmpeg Filters Documentation: concat 等引用资料中对该命令形式的理解和 Concatenate Videos Together Using FFMPEG! .
会发生什么: ffmpeg在检查每个流的元数据然后开始处理时会提供大量输出。在短暂的持续时间(几秒到一分钟左右，似乎与第一个视频的持续时间成比例)后，我开始看到这样的消息:

More than 1000 frames duplicated
More than 10000 frames duplicated     512kB time=00:00:00.12 bitrate=32771.0kbits/s dup=33365 drop=0 speed=0.00449x
More than 100000 frames duplicated   1280kB time=00:00:00.17 bitrate=61442.1kbits/s dup=66730 drop=0 speed=0.00272x

...然后这个过程永远不会完成。如果我让我的电脑运行 24 小时， ffmpeg仍在使用最大可用 CPU (200-300%)。输出文件的长度为 48 字节。
注:每个输入只需几分钟，因此单独重新编码输入只需几分钟。
注:如果我将命令更改为使用 f01.mp4对于源 0 和源 1，命令在 5 分钟内按预期完成:

% # example that works:
% # note, however, that this just repeats the same source twice
% ffmpeg -i f01.mp4 -i f01.mp4 -filter_complex "[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1[v][a]" -map "[v]" -map "[a]" output.mp4

完整输出:
以下是运行的完整输出，以防有帮助:

% ffmpeg -i f01.mp4 -i f02.mp4 -filter_complex "[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1[v][a]" -map "[v]" -map "[a]" output.mp4
ffmpeg version 4.3 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.62)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'f01.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2020-06-04T21:34:26.000000Z
    encoder         : HandBrake 1.3.2 2020050300
  Duration: 00:04:14.66, start: 0.000000, bitrate: 525 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt709), 708x478 [SAR 8:9 DAR 944:717], 366 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2020-06-04T21:34:26.000000Z
      handler_name    : VideoHandler
    Stream #0:1(jpn): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 149 kb/s (default)
    Metadata:
      creation_time   : 2020-06-04T21:34:26.000000Z
      handler_name    : Stereo
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'f02.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2020-06-04T21:38:15.000000Z
    encoder         : HandBrake 1.3.2 2020050300
  Duration: 00:06:30.95, start: 0.000000, bitrate: 1328 kb/s
    Stream #1:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt709), 708x478 [SAR 8:9 DAR 944:717], 1179 kb/s, 29.97 fps, 30 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2020-06-04T21:38:15.000000Z
      handler_name    : VideoHandler
    Stream #1:1(jpn): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 140 kb/s (default)
    Metadata:
      creation_time   : 2020-06-04T21:38:15.000000Z
      handler_name    : Stereo
File 'output.mp4' already exists. Overwrite? [y/N] y
Stream mapping:
  Stream #0:0 (h264) -> concat:in0:v0
  Stream #0:1 (aac) -> concat:in0:a0
  Stream #1:0 (h264) -> concat:in1:v0
  Stream #1:1 (aac) -> concat:in1:a0
  concat:out:v0 -> Stream #0:0 (libx264)
  concat:out:a0 -> Stream #0:1 (aac)
Press [q] to stop, [?] for help
[mp4 @ 0x7ff130014000] Frame rate very high for a muxer not efficiently supporting it.
Please consider specifying a lower framerate, a different muxer or -vsync 2
[libx264 @ 0x7ff130021200] using SAR=8/9
[libx264 @ 0x7ff130021200] MB rate (1350000000) > level limit (16711680)
[libx264 @ 0x7ff130021200] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x7ff130021200] profile High, level 6.2, 4:2:0, 8-bit
[libx264 @ 0x7ff130021200] 264 - core 160 r3011 cde9a93 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'output.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
    Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p(progressive), 708x478 [SAR 8:9 DAR 944:717], q=-1--1, 1000k tbn, 1000k tbc (default)
    Metadata:
      encoder         : Lavc58.91.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      encoder         : Lavc58.91.100 aac
More than 1000 frames duplicated
More than 10000 frames duplicated     512kB time=00:00:00.12 bitrate=32771.0kbits/s dup=33365 drop=0 speed=0.00449x
More than 100000 frames duplicated   1280kB time=00:00:00.17 bitrate=61442.1kbits/s dup=66730 drop=0 speed=0.00272x
frame=667333 fps=1079 q=33.0 size=   14848kB time=00:00:00.76 bitrate=158379.2kbits/s dup=667312 drop=0 speed=0.00124x

Answer 1

正如日志中的警告所说，Frame rate very high for a muxer not efficiently supporting it.发生这种情况是因为 concat 取消设置流帧速率，当 tbr的所有视频流不匹配。 ffmpeg 然后将使用 time_base 作为有效帧速率，然后复制帧以匹配该帧速率。在这种情况下，它是 90000，因此这有效地爆炸了资源使用并减慢了进程。
添加 -vsync 2以避免帧重复。ffmpeg -i f01.mp4 -i f02.mp4 -filter_complex "[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1[v][a]" -vsync 2 -map "[v]" -map "[a]" output.mp4