我有一个 AVI 视频，我想减小文件大小。当我运行下面的 FFmpeg 命令时，视频中产生的音频会加速，并且视频的最后一部分没有音频。我使用 VLC 媒体播放器播放所有视频。
FFmpeg 命令
ffmpeg -i "in.avi" -vcodec libx264 -acodec copy -crf 26 -vf "scale=-1:'min(720,ih)', yadif=1" out.avi
输出消息
ffmpeg version 2023-06-11-git-09621fd7d9-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
libavutil 58. 13.100 / 58. 13.100
libavcodec 60. 17.100 / 60. 17.100
libavformat 60. 6.100 / 60. 6.100
libavdevice 60. 2.100 / 60. 2.100
libavfilter 9. 8.101 / 9. 8.101
libswscale 7. 3.100 / 7. 3.100
libswresample 4. 11.100 / 4. 11.100
libpostproc 57. 2.100 / 57. 2.100
[avi @ 000002255f70d540] Switching to NI mode, due to poor interleaving
Input #0, avi, from 'in.avi':
Duration: 00:10:40.64, start: 0.000000, bitrate: 28852 kb/s
Stream #0:0: Video: dvvideo, yuv411p, 720x480 [SAR 32:27 DAR 16:9], 25000 kb/s, SAR 8:9 DAR 4:3, 60k fps, 29.97 tbr, 60k tbn
Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Stream #0:2: Audio: pcm_s16le, 32000 Hz, stereo, s16, 1024 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (dvvideo (native) -> h264 (libx264))
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[libx264 @ 000002255fbc4940] using SAR=8/9
[libx264 @ 000002255fbc4940] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 000002255fbc4940] profile High 4:2:2, level 3.1, 4:2:2, 8-bit
Output #0, avi, to 'out.avi':
Metadata:
ISFT : Lavf60.6.100
Stream #0:0: Video: h264 (H264 / 0x34363248), yuv422p(tv, progressive), 720x480 [SAR 8:9 DAR 4:3], q=2-31, 59.94 fps, 59.94 tbn
Metadata:
encoder : Lavc60.17.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
[dvvideo @ 000002255fb36d80] Concealing bitstream errors.33 bitrate=2437.5kbits/s speed=0.902x
Last message repeated 15 times
[dvvideo @ 000002255fb36d80] Concealing bitstream errors.77 bitrate=2439.5kbits/s speed=0.902x
Last message repeated 60 times
[dvvideo @ 0000022560071680] Concealing bitstream errors.72 bitrate=2461.8kbits/s speed=0.895x
Last message repeated 18 times
[dvvideo @ 0000022560071680] Concealing bitstream errors.12 bitrate=2459.9kbits/s speed=0.894x
[out#0/avi @ 000002255f70d8c0] video:110055kB audio:80088kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.724923%
frame=38400 fps= 57 q=-1.0 Lsize= 191521kB time=00:10:40.60 bitrate=2449.2kbits/s speed=0.946x
[libx264 @ 000002255fbc4940] frame I:165 Avg QP:27.36 size: 37180
[libx264 @ 000002255fbc4940] frame P:9710 Avg QP:30.58 size: 7328
[libx264 @ 000002255fbc4940] frame B:28525 Avg QP:35.24 size: 1241
[libx264 @ 000002255fbc4940] consecutive B-frames: 0.8% 0.3% 0.3% 98.6%
[libx264 @ 000002255fbc4940] mb I I16..4: 10.3% 67.6% 22.1%
[libx264 @ 000002255fbc4940] mb P I16..4: 1.0% 3.8% 0.8% P16..4: 40.7% 12.1% 8.6% 0.0% 0.0% skip:33.0%
[libx264 @ 000002255fbc4940] mb B I16..4: 0.1% 0.2% 0.0% B16..8: 36.9% 1.8% 0.4% direct: 1.4% skip:59.1% L0:45.0% L1:51.8% BI: 3.1%
[libx264 @ 000002255fbc4940] 8x8 transform intra:66.5% inter:68.7%
[libx264 @ 000002255fbc4940] coded y,uvDC,uvAC intra: 60.3% 64.7% 10.1% inter: 10.7% 6.9% 0.1%
[libx264 @ 000002255fbc4940] i16 v,h,dc,p: 21% 35% 10% 34%
[libx264 @ 000002255fbc4940] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 23% 19% 6% 8% 7% 12% 6% 9%
[libx264 @ 000002255fbc4940] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 13% 25% 16% 6% 10% 7% 12% 5% 6%
[libx264 @ 000002255fbc4940] i8c dc,h,v,p: 58% 19% 18% 5%
[libx264 @ 000002255fbc4940] Weighted P-Frames: Y:3.0% UV:1.5%
[libx264 @ 000002255fbc4940] ref P L0: 56.9% 16.8% 19.3% 6.7% 0.2%
[libx264 @ 000002255fbc4940] ref B L0: 87.5% 10.4% 2.2%
[libx264 @ 000002255fbc4940] ref B L1: 93.2% 6.8%
[libx264 @ 000002255fbc4940] kb/s:1407.29
由于音频流被复制，我不明白为什么产生的音频听起来会加快。视频看起来不错，只是音频有问题。
我也尝试了其他选项，例如将音频转换为 aac 或 mp3，但生成的音频听起来仍然加速且音调较高。
是否有人知道为什么音频没有像原始 AVI 视频中的声音那样简单地被复制，并且您对如何解决此问题有什么建议吗？
编辑：我尝试降低使用此命令的频率：
ffmpeg -i in.avi -ar 32000 -vcodec libx264 -crf 26 -vf "scale=-1:'min(720,ih)', yadif=1" out.avi
结果是一样的，有这样的错误信息：
[pcm_s16le @ 000001a6364d0040] This decoder does not support parameter changes, but PARAM_CHANGE side data was sent to it.
[pcm_s16le @ 000001a6364d0040] Error applying parameter changes.
好像无法编辑音频。有人知道为什么会出现这个错误吗？
答案1
通过像这样降低音调来消除高音调（解决方法）：
ffmpeg -i in.avi -af "asetrate=32000" -vcodec libx264 -crf 26 -vf "scale=-1:'min(720,ih)', yadif=1" out.avi
请记住，这只是一种解决方法，并不保证一定有效