video - ffmpeg 在子剪辑上运行时出现转换失败

Question

我有一个主视频剪辑，我正在使用 ffmpeg 从中生成一个子剪辑。我用来生成子剪辑的命令是:

ffmpeg -i {input_video} -ss {start_time} -to {end_time} {output_filename}

获得子剪辑后，我将执行以下操作:

第 1 步:我正在使用 ffprobe 计算平均帧速率:

ffprobe -v error -select_streams v:0 -show_entries stream=avg_frame_rate -of default=noprint_wrappers=1:nokey=1 <input file>

第 2 步:我正在提取原始视频流并将其存储在临时位置，并使用以下方法删除现有的 PTS 值:

ffmpeg -i <input video> -c:v copy -an $TMP_STREAM 2>&1

第 3 步:我将视频重新混合到一个容器中，强制平均 FPS 导致 PTS 值被重写:

ffmpeg-r <FPS> -i $TMP_STREAM -c:v copy $OUTPUT_FILE 2>&1

当我在主视频剪辑上执行上述 3 个步骤时，它工作得很好。但是当我对子剪辑(我使用 ffmpeg 生成)执行这些步骤时，第 3 步给了我错误:

Can't write packet with unknown timestamp
av_interleaved_write_frame(): Invalid argument

关于可能发生的事情的任何意见？

以下是我的命令和日志:

命令 1:
ffprobe -v 错误 -select_streams v:0 -show_entries stream=avg_frame_rate -of default=noprint_wrappers=1:nokey=1 abcd.mp4。

---> 输出:287/12

命令 2:
ffmpeg -i abcd.mp4 -c:v 复制 -an/tmp/tmp.h264 2>&1

---> 输出:

ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.9.4 (GCC)
  configuration: --prefix=/local/p4clients/pkgbuild-DlViY/workspace/src/FFmpeg/build/private/install --disable-static --enable-gpl --enable-libx264 --enable-shared --enable-encoder=vorbis --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libebur128
  libavutil      55. 34.101 / 55. 34.101
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.101 / 57. 56.101
  libavdevice    57.  1.100 / 57.  1.100
  libavfilter     6. 65.100 /  6. 65.100
  libswscale      4.  2.100 /  4.  2.100
  libswresample   2.  3.100 /  2.  3.100
  libpostproc    54.  1.100 / 54.  1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'subclip_fv_1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.56.101
  Duration: 00:00:29.44, start: 0.000000, bitrate: 329 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 300 kb/s, 23.92 fps, 23.92 tbr, 18368 tbn, 47.83 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 8000 Hz, mono, fltp, 26 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
File '/tmp/tmp.h264' already exists. Overwrite ? [y/N] y
Output #0, h264, to '/tmp/tmp.h264':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.56.101
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 300 kb/s, 23.92 fps, 23.92 tbr, 23.92 tbn, 23.92 tbc (default)
    Metadata:
      handler_name    : VideoHandler
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=  703 fps=0.0 q=-1.0 Lsize=    1077kB time=00:00:29.31 bitrate= 301.1kbits/s speed=4.47e+03x
video:1077kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.010517%

命令 3:
ffmpeg -r 287/12 -i/tmp/tmp.h264 -c:v 复制 abcd.mp4_retimed.mkv 2>&1

----> 输出:

ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.9.4 (GCC)
  configuration: --prefix=/local/p4clients/pkgbuild-DlViY/workspace/src/FFmpeg/build/private/install --disable-static --enable-gpl --enable-libx264 --enable-shared --enable-encoder=vorbis --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libebur128
  libavutil      55. 34.101 / 55. 34.101
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.101 / 57. 56.101
  libavdevice    57.  1.100 / 57.  1.100
  libavfilter     6. 65.100 /  6. 65.100
  libswscale      4.  2.100 /  4.  2.100
  libswresample   2.  3.100 /  2.  3.100
  libpostproc    54.  1.100 / 54.  1.100
Input #0, h264, from '/tmp/tmp.h264':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: h264 (High), yuv420p(progressive), 640x480 [SAR 1:1 DAR 4:3], 23.92 fps, 23.92 tbr, 1200k tbn, 47.83 tbc
Output #0, matroska, to 'subclip_fv_1.mp4_retimed.mkv':
  Metadata:
    encoder         : Lavf57.56.101
    Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p(progressive), 640x480 [SAR 1:1 DAR 4:3], q=2-31, 23.92 fps, 23.92 tbr, 1k tbn, 23.92 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[matroska @ 0x43d880] Timestamps are unset in a packet for stream 0. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
[matroska @ 0x43d880] Can't write packet with unknown timestamp
av_interleaved_write_frame(): Invalid argument

Answer 1

第三步依赖于输出复用器在没有输入时间戳的情况下分配时间戳。在常见的复用器中，只有 MP4 会这样做，所以

ffmpeg-r 287/12 -i /tmp/tmp.h264 -c:v copy abcd.mp4_retimed.mp4

获得 MP4 后，您可以运行

ffmpeg -i abcd.mp4_retimed.mp4 -c copy abcd.mp4_retimed.mkv