使用ffmpeg将PAL标准视频（720×576[785 × 576]）中的MP4文件转换为720×576？

Question

我有一个 MP4 格式的视频文件，据称其分辨率为 720×576，但根据 Mac 上的 Finder 显示为 786 × 576:

作为此处讨论的一部分，有人向我指出这可能是因为该文件是 PAL 标准视频，据此这是预期的行为。我想使用 ffmpeg 更改它，以便文件实际上不再是 PAL 标准视频，但宽度始终只有 720 像素。

为此，我被指向此 question 以找到相应的 ffmpeg 命令。然而，当我尝试运行 ffmpeg -i weird_video.mp4 -vf "scale=iw*sar:ih,setsar=1" -crf 28 -c:a aac -b:a 80k -ac 1 -movflags +faststart h-264-out.mp4 时，我收到一条错误消息，因为视频的实际宽度似乎是 785，而不是 finder 指示的 786 像素：

ffmpeg -i weird_video.mp4 -vf "scale=iw*sar:ih,setsar=1" -crf 28 -c:a aac -b:a 80k -ac 1 -movflags +faststart h-264-out.mp4
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 12.0.0 (clang-1200.0.32.29)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1_9 --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-libxml2 --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-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox
  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 'weird_video.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.29.100
  Duration: 00:00:12.27, start: 0.000000, bitrate: 585 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt470bg/bt470bg/smpte170m), 720x576 [SAR 131:120 DAR 131:96], 577 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 2 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x7fd77e00b600] width not divisible by 2 (785x576)
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
[aac @ 0x7fd77e00ce00] Qavg: 63846.375
[aac @ 0x7fd77e00ce00] 2 frames left in the queue on closing
Conversion failed!

当我运行 ffmpeg -i <myvideo> 我得到以下信息：

ffmpeg -i weird_video.mp4
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 12.0.0 (clang-1200.0.32.29)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1_9 --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-libxml2 --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-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox
  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 'weird_video.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.29.100
  Duration: 00:00:12.27, start: 0.000000, bitrate: 585 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt470bg/bt470bg/smpte170m), 720x576 [SAR 131:120 DAR 131:96], 577 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 2 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
At least one output file must be specified

我在视频编辑器 Shotcut 中打开视频，宽度为 785 而不是 786，这符合 ffmpeg 失败的原因：

因此，我的问题是，是否有一种方法可以使用 ffmpeg 转换视频，尽管它有 785 像素的奇怪宽度？

如有任何帮助，我们将不胜感激！

Answer 1

要将非方形像素转换为方形像素并裁剪至所需宽度：

ffmpeg -i weird_video.mp4 -vf "scale=iw*sar:ih,crop=720:ih,setsar=1" -crf 28 -c:a aac -b:a 80k -ac 1 -movflags +faststart h-264-out.mp4

有关详细信息，请参阅 scale, crop, and setsar 过滤器文档。

使用ffmpeg将PAL标准视频（720×576[785 × 576]）中的MP4文件转换为720×576？

Convert MP4 file in PAL standard video (720×576[785 × 576]) to 720×576 using ffmpeg?

video

ffmpeg

crop

resolution

aspect-ratio