>更新：
已尝试从颈胡子推荐的命令：
ffmpeg -analyzeduration 10M -probesize 10M -i Webpfile.webp -c:v libx264 output.mp4
下面是输出(文件路径通用化(：
User-macbookpro:~ User$ ffmpeg -analyzeduration 10M -probesize 10M -i Webpfile.webp -c:v libx264 output.mp4
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
built with Apple LLVM version 9.0.0 (clang-900.0.38)
configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libopenh264 --enable-libopus --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-libopenjpeg --disable-decoder=jpeg2000 --extra-cflags=-I/usr/local/Cellar/openjpeg/2.3.0/include/openjpeg-2.3 --enable-nonfree
libavutil 55. 78.100 / 55. 78.100
libavcodec 57.107.100 / 57.107.100
libavformat 57. 83.100 / 57. 83.100
libavdevice 57. 10.100 / 57. 10.100
libavfilter 6.107.100 / 6.107.100
libavresample 3. 7. 0 / 3. 7. 0
libswscale 4. 8.100 / 4. 8.100
libswresample 2. 9.100 / 2. 9.100
libpostproc 54. 7.100 / 54. 7.100
[webp @ 0x7f9920811000] skipping unsupported chunk: ANIM
[webp @ 0x7f9920811000] skipping unsupported chunk: ANMF
Last message repeated 14 times
[webp @ 0x7f9920811000] image data not found
[webp_pipe @ 0x7f9920000e00] decoding for stream 0 failed
[webp_pipe @ 0x7f9920000e00] Could not find codec parameters for stream 0 (Video: webp, none): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, webp_pipe, from 'webpfile.webp':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: webp, none, 25 tbr, 25 tbn, 25 tbc
File 'output.mp4' already exists. Overwrite ? [y/N] y
Stream mapping:
Stream #0:0 -> #0:0 (webp (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[webp @ 0x7f9920005e00] skipping unsupported chunk: ANIM
[webp @ 0x7f9920005e00] skipping unsupported chunk: ANMF
Last message repeated 14 times
[webp @ 0x7f9920005e00] image data not found
Error while decoding stream #0:0: Invalid data found when processing input
Finishing stream 0:0 without any data written to it.
Nothing was written into output file 0 (output.mp4), because at least one of its streams received no packets.
frame= 0 fps=0.0 q=0.0 Lsize= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)
Conversion failed!
目前我正在尝试将 webp 转换回 mp4，但收到错误：
Nothing was written into output file 0 (output.mp4), because at least one of its streams received no packets.
这是我一直在使用的当前命令，但没有成功：
ffmpeg -i webpfile.webp -c:v libx264 output.mp4
我注意到处理过程中还有其他错误，标注
Skipping unsupported chunk: ANIM
Skipping unsupported chunk: ANMF
和
Could not find codec parameters for stream 0 (Video: webp, none): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
我在这里做错了什么？ 我以为这就像我将电影转换为 webp 一样简单，但走另一条路似乎更微妙。
根据此 FFmpeg 票证，尚不支持解码动画 webp 文件。
https://trac.ffmpeg.org/ticket/4907
目前，FFmpeg可以编码动画WebP，但无法解码，这对用户来说很不方便。
由于"不支持的块"，现在解码动画 WebP 会生成"找不到图像数据错误"：https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/webp.c#L1504
当前工单状态：开放增强