我一直在使用ffmpeg将mkv转换为mp4，下面是我使用的命令。
ffmpeg -i demo.mkv -vcodec libx264 -vprofile high -crf 28 -c:v h264 demo.mp4
但现在我在尝试转换一个新的mkv文件时出错了。我在网上做了大量的搜索，但到目前为止我还没能找到解决方案。
以下是屏幕输出，其中包括版本和库信息。
ffmpeg version N-101385-gb34d1de Copyright (c) 2000-2021 the FFmpeg developers
built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.4)
configuration: --enable-gpl --enable-nonfree --enable-libx264 --enable-libmp3lame --enable-libass
libavutil 56. 66.100 / 56. 66.100
libavcodec 58.128.100 / 58.128.100
libavformat 58. 70.100 / 58. 70.100
libavdevice 58. 12.100 / 58. 12.100
libavfilter 7.107.100 / 7.107.100
libswscale 5. 8.100 / 5. 8.100
libswresample 3. 8.100 / 3. 8.100 libpostproc 55. 8.100 / 55. 8.100
[av1 @ 0x2e66180] Your platform doesn't suppport hardware accelerated AV1 decoding.
[av1 @ 0x2e66180] Failed to get pixel format.
[av1 @ 0x2e66180] Missing Sequence Header.
Last message repeated 122 times [av1 @ 0x2e66180] video_get_buffer: image parameters invalid
[av1 @ 0x2e66180] get_buffer() failed
[av1 @ 0x2e66180] thread_get_buffer() failed
[av1 @ 0x2e66180] Failed to allocate space for current frame.
[av1 @ 0x2e66180] Get current frame error
[matroska,webm @ 0x2e62580] decoding for stream 0 failed
[matroska,webm @ 0x2e62580] Could not find codec parameters for stream 0 (Video: av1 (Main), none(tv, bt709), 1920x1072 [SAR 1:1 DAR 120:67]): unspecified pixel format
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, matroska,webm, from 'demo.mkv':
Metadata:
COMPATIBLE_BRANDS: iso6av01mp41
MAJOR_BRAND : dash
MINOR_VERSION : 0
ENCODER : Lavf58.70.100
Duration: 00:13:39.08, start: -0.007000, bitrate: 779 kb/s
Stream #0:0: Video: av1 (Main), none(tv, bt709), 1920x1072 [SAR 1:1 DAR 12 0:67], 25 fps, 25 tbr, 1k tbn, 1k tbc (default)
Metadata:
HANDLER_NAME : ISO Media file produced by Google Inc.
VENDOR_ID : [0][0][0][0]
DURATION : 00:13:39.000000000
Stream #0:1(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
Metadata:
DURATION : 00:13:39.081000000
Multiple -c, -codec, -acodec, -vcodec, -scodec or -dcodec options specified for stream 0, only the last option '-c:v h264' will be used.
Stream mapping:
Stream #0:0 -> #0:0 (av1 (native) -> h264 (libx264))
Stream #0:1 -> #0:1 (opus (native) -> aac (native))
Press [q] to stop, [?] for help
[av1 @ 0x2e6ad40] Your platform doesn't suppport hardware accelerated AV1 decoding.
[av1 @ 0x2e6ad40] Failed to get pixel format.
Error while decoding stream #0:0: Function not implemented
[av1 @ 0x2e6ad40] Missing Sequence Header.
Error while decoding stream #0:0: Invalid data found when processing input
... [the above two lines repeated dozens of times]
[av1 @ 0x2e6ad40] video_get_buffer: image parameters invalid
[av1 @ 0x2e6ad40] get_buffer() failed
[av1 @ 0x2e6ad40] thread_get_buffer() failed
[av1 @ 0x2e6ad40] Failed to allocate space for current frame.
[av1 @ 0x2e6ad40] Get current frame error
Error while decoding stream #0:0: Invalid argument
... [the above 6 lines repeated hundreds of times]
[av1 @ 0x2e6ad40] Failed to get reference frame.
Error while decoding stream #0:0: Invalid argument
Cannot determine format of input stream 0:0 after EOF
Error marking filters as finished
[aac @ 0x2ed0f00] Qavg: 3268.314
[aac @ 0x2ed0f00] 2 frames left in the queue on closing
Conversion failed!
请注意，三个点(…(表示重复多次的省略行。感谢您的帮助。
您的输入视频流使用AV1编解码器，正如日志所示，
Your platform doesn't suppport hardware accelerated AV1 decoding.
您将需要一个支持AV1解码器(如libdav1d(的ffmpeg构建。可在https://johnvansickle.com/ffmpeg/