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使用 ffmpeg 将 AVI 转码为 MP4 时缩略图消失

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使用 ffmpeg 将 AVI 转码为 MP4 时缩略图消失

当我尝试使用 ffmpeg 将非常旧的 avi 转换为 mp4 时，缩略图消失了。有没有办法保留缩略图或直接从视频流自动生成缩略图，例如使用第一帧，而不必保存图像然后添加它？使用 Win10 并尝试在 Windows 资源管理器中查看文件。

日志：

ffmpeg version git-2020-07-16-d11cc74 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200621
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --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-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 55.100 / 56. 55.100
  libavcodec     58. 96.100 / 58. 96.100
  libavformat    58. 48.100 / 58. 48.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Guessed Channel Layout for Input Stream #0.1 : mono
Input #0, avi, from 'in.avi':
  Metadata:
    creation_time   : 2004-03-14 13:53:17
    encoder         : CanonMVI01
  Duration: 00:00:30.00, start: 0.000000, bitrate: 5217 kb/s
    Stream #0:0: Video: mjpeg (Baseline) (MJPG / 0x47504A4D), yuvj422p(pc, bt470bg/unknown/unknown), 640x480, 5136 kb/s, 15 fps, 15 tbr, 15 tbn, 15 tbc
    Stream #0:1: Audio: pcm_u8 ([1][0][0][0] / 0x0001), 11024 Hz, mono, u8, 88 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (pcm_u8 (native) -> aac (native))
Press [q] to stop, [?] for help
[aac @ 0000023cd2571a40] Too many bits 17832.925170 > 6144 per frame requested, clamping to max
[libx264 @ 0000023cd256fb00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0000023cd256fb00] profile High 4:2:2, level 2.2, 4:2:2, 8-bit
[libx264 @ 0000023cd256fb00] 264 - core 160 - 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=15 scenecut=40 intra_refresh=0 rc=cqp mbtree=0 qp=15 ip_ratio=1.40 pb_ratio=1.30 aq=0
Output #0, mp4, to 'out.mp4':
  Metadata:
    encoder         : Lavf58.48.100
    Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuvj422p(pc), 640x480, q=-1--1, 15 fps, 500k tbn, 15 tbc
    Metadata:
      encoder         : Lavc58.96.100 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), 11025 Hz, mono, fltp, 66 kb/s
    Metadata:
      encoder         : Lavc58.96.100 aac
frame=  450 fps= 32 q=-1.0 Lsize=   21274kB time=00:00:30.00 bitrate=5809.2kbits/s speed=2.15x
video:21065kB audio:195kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.062795%
[libx264 @ 0000023cd256fb00] frame I:2     Avg QP:12.00  size: 59822
[libx264 @ 0000023cd256fb00] frame P:117   Avg QP:15.00  size: 57718
[libx264 @ 0000023cd256fb00] frame B:331   Avg QP:16.66  size: 44404
[libx264 @ 0000023cd256fb00] consecutive B-frames:  1.3%  0.9%  2.7% 95.1%
[libx264 @ 0000023cd256fb00] mb I  I16..4:  0.1% 99.5%  0.3%
[libx264 @ 0000023cd256fb00] mb P  I16..4:  0.0% 55.3%  7.8%  P16..4:  9.2% 16.1% 11.5%  0.0%  0.0%    skip: 0.0%
[libx264 @ 0000023cd256fb00] mb B  I16..4:  0.1% 25.5%  0.3%  B16..8: 25.6% 19.7%  7.7%  direct:20.1%  skip: 1.0%  L0:17.5% L1:13.5% BI:69.0%
[libx264 @ 0000023cd256fb00] 8x8 transform intra:93.4% inter:84.1%
[libx264 @ 0000023cd256fb00] coded y,uvDC,uvAC intra: 98.8% 79.8% 22.5% inter: 97.3% 94.2% 42.8%
[libx264 @ 0000023cd256fb00] i16 v,h,dc,p:  4% 25% 16% 55%
[libx264 @ 0000023cd256fb00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 19% 52%  2%  2%  2%  4%  2%  5%
[libx264 @ 0000023cd256fb00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 13% 20% 15%  7%  9%  6% 11%  6% 13%
[libx264 @ 0000023cd256fb00] i8c dc,h,v,p: 45% 21% 33%  2%
[libx264 @ 0000023cd256fb00] Weighted P-Frames: Y:6.0% UV:1.7%
[libx264 @ 0000023cd256fb00] ref P L0: 38.4% 25.7% 19.4% 15.7%  0.8%
[libx264 @ 0000023cd256fb00] ref B L0: 88.3%  9.6%  2.1%
[libx264 @ 0000023cd256fb00] ref B L1: 94.8%  5.2%
[libx264 @ 0000023cd256fb00] kb/s:5752.13
[aac @ 0000023cd2571a40] Qavg: 58267.156

答案1

添加-vf format=yuv420p：

ffmpeg -i in.avi -qp 15 -c:v h264 -c:a aac -b:a 192k -vf format=yuv420p out.mp4

这将使用兼容的色度二次采样方案。否则，编码器 libx264 将选择最类似于输入的色度二次采样，但大多数播放器或文件管理器无法读取。

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