FFmpeg 错误“轨道 X：编解码器帧大小未设置”

Question

我刚刚发现 FFmpeg，我需要它来将大量 MP4 文件剪切到每个文件的最后 20 秒。每个 MP4 文件都有一个视频轨道和两个音频轨道。

我一直在使用这行代码：

for %F in (*.mp4) do ffmpeg -sseof -20 -i "%F" -map 0:v -map 0:a -c:v copy -c:a copy "%~nF_trimmed.mp4"

修剪顺利，但音频存在问题。在没有取消修剪过程的情况下出现此错误：

[mp4 @ 0000025740443740] track 1: codec frame size is not set
[mp4 @ 0000025740443740] track 2: codec frame size is not set

 

请记住，我不熟悉编码，我只需要它来进行视频编辑目的。我一直在尝试寻找解决方法，但我没有运气。有任何想法吗？

如果有用的话，这是控制台完整流程：

D:\User Libraries\Desktop\Test>for %F in (*.mp4) do ffmpeg -sseof -20 -i "%F" -map 0:v -map 0:a -c:v copy -c:a copy "%~nF_trimmed.mp4"

D:\User Libraries\Desktop\Test>ffmpeg -sseof -20 -i "Test1.mp4" -map 0:v -map 0:a -c:v copy -c:a copy "Test1_trimmed.mp4"
ffmpeg version N-91024-g293a6e8332 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 7.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --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-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
  libavutil      56. 18.100 / 56. 18.100
  libavcodec     58. 19.101 / 58. 19.101
  libavformat    58. 13.102 / 58. 13.102
  libavdevice    58.  4.100 / 58.  4.100
  libavfilter     7. 21.100 /  7. 21.100
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Test1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2018-05-05T06:59:14.000000Z
    date            : 2018
  Duration: 00:02:57.53, start: 0.000000, bitrate: 48706 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt470m), 1920x1080 [SAR 1:1 DAR 16:9], 48332 kb/s, 59.83 fps, 59.94 tbr, 90k tbn, 120 tbc (default)
    Metadata:
      creation_time   : 2018-05-05T06:59:14.000000Z
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 171 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T06:59:14.000000Z
      handler_name    : SoundHandle
    Stream #0:2(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T06:59:14.000000Z
      handler_name    : SoundHandle
Output #0, mp4, to 'Test1_trimmed.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    date            : 2018
    encoder         : Lavf58.13.102
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt470m), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 48332 kb/s, 59.83 fps, 59.94 tbr, 90k tbn, 90k tbc (default)
    Metadata:
      creation_time   : 2018-05-05T06:59:14.000000Z
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 171 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T06:59:14.000000Z
      handler_name    : SoundHandle
    Stream #0:2(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T06:59:14.000000Z
      handler_name    : SoundHandle
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)
Press [q] to stop, [?] for help
frame= 1211 fps=833 q=-1.0 Lsize=  124193kB time=00:00:19.98 bitrate=50911.9kbits/s speed=13.8x
video:123268kB audio:887kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.030864%

D:\User Libraries\Desktop\Test>ffmpeg -sseof -20 -i "Test2.mp4" -map 0:v -map 0:a -c:v copy -c:a copy "Test2_trimmed.mp4"
ffmpeg version N-91024-g293a6e8332 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 7.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --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-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
  libavutil      56. 18.100 / 56. 18.100
  libavcodec     58. 19.101 / 58. 19.101
  libavformat    58. 13.102 / 58. 13.102
  libavdevice    58.  4.100 / 58.  4.100
  libavfilter     7. 21.100 /  7. 21.100
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Test2.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2018-05-05T07:02:30.000000Z
    date            : 2018
  Duration: 00:02:36.73, start: 0.000000, bitrate: 49260 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt470m), 1920x1080 [SAR 1:1 DAR 16:9], 48916 kb/s, 58.73 fps, 59.94 tbr, 90k tbn, 120 tbc (default)
    Metadata:
      creation_time   : 2018-05-05T07:02:30.000000Z
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 139 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T07:02:30.000000Z
      handler_name    : SoundHandle
    Stream #0:2(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T07:02:30.000000Z
      handler_name    : SoundHandle
[mp4 @ 000001cf28f53740] track 1: codec frame size is not set
[mp4 @ 000001cf28f53740] track 2: codec frame size is not set
Output #0, mp4, to 'Test2_trimmed.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    date            : 2018
    encoder         : Lavf58.13.102
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt470m), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 48916 kb/s, 58.73 fps, 59.94 tbr, 90k tbn, 90k tbc (default)
    Metadata:
      creation_time   : 2018-05-05T07:02:30.000000Z
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 139 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T07:02:30.000000Z
      handler_name    : SoundHandle
    Stream #0:2(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      creation_time   : 2018-05-05T07:02:30.000000Z
      handler_name    : SoundHandle
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)
Press [q] to stop, [?] for help
frame= 1225 fps=834 q=-1.0 Lsize=  125448kB time=00:00:19.98 bitrate=51429.4kbits/s speed=13.6x
video:124591kB audio:815kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.034254%

Answer 1

此警告消息的来源指示来自 ffmpeg MKV 到 MP4 后错误 track 1: codec frame size is not set。

Gyan 的回答是 这样说的：

MP4 写入器尝试确定音轨是否为 VBR，以便其必须写入一些进一步的元数据。它检查编码的音频帧大小作为其中的一部分。MKV 编写者不会这样做。

由于您正在重新混合，因此该数据不适用于 Opus，因此作者抱怨道。但该文件没有任何缺陷。

我将更改该消息的日志级别 - 这并不是一般用户需要关心的事情。

我的理解是，首先，该消息与要写入结果视频标题的元数据有关，并且对视频本身的正确性没有影响。这意味着它可以被忽略（上面的答案说它确实应该被最终用户忽略）。

其次，这意味着由于视频和音频在任意点被切割，因此视频和音频需要重新混合，意味着分离和重新编码（至少在切割点周围），这会导致音频编码器出现问题，同时没有可用的视频数据来补充其元数据。

无论如何，最终的视频文件应该是正确的，没有不利影响。您可以忽略此警告，