ffmpeg: add libwebp support

[seamusdemora (Seamus)]

I gather that 'libwebp' is not included with the 'ffmpeg' port. I found a recipe for converting an 'mp4' to a 'webp', but all I got for that was the error 'Unknown encoder 'libwebp.

I followed Google's advice & tried to build 'libwebp' following these instructions: ​https://developers.google.com/speed/webp/docs/compiling#building

But this did not work either. I got the exact same error message. FWIW, here's the command I was trying to use:

ffmpeg -i "JW-recording.mp4" \ 
-vf "fps=10,scale=720:-1:flags=lanczos" \
-vcodec libwebp -lossless 0 -compression_level 6 \
-q:v 50 -loop 0 \
-preset picture -an -vsync 0 JW-recording.webp

ffmpeg version 4.4.4 Copyright (c) 2000-2023 the FFmpeg developers
  built with Apple clang version 14.0.3 (clang-1403.0.22.14.1)
  configuration: --prefix=/opt/local --cc=/usr/bin/clang --mandir=/opt/local/share/man --enable-audiotoolbox --disable-indev=jack --disable-libjack --disable-libopencore-amrnb --disable-libopencore-amrwb --disable-libxcb --disable-libxcb-shm --disable-libxcb-xfixes --enable-opencl --disable-outdev=xv --enable-sdl2 --disable-securetransport --enable-videotoolbox --enable-avfilter --enable-avresample --enable-fontconfig --enable-gnutls --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libfribidi --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libzimg --enable-libzvbi --enable-lzma --enable-pthreads --enable-shared --enable-swscale --enable-zlib --enable-libaom --enable-libsvtav1 --arch=arm64 --enable-gpl --enable-libvidstab --enable-libx264 --enable-libx265 --enable-libxvid --enable-postproc
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
[libdav1d @ 0x12e815e00] libdav1d 1.4.3
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'JW-recording.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomav01iso2mp41
    encoder         : Lavf58.76.100
  Duration: 00:00:05.50, start: 0.000000, bitrate: 106 kb/s
  Stream #0:0(und): Video: av1 (Main) (av01 / 0x31307661), yuv420p(tv, progressive), 460x332 [SAR 1:1 DAR 115:83], 104 kb/s, 10 fps, 10 tbr, 10240 tbn, 10240 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]

Unknown encoder 'libwebp'     <===ERROR MESSAGE

I did set the environment variable for 'LD_LIBRARY_PATH' as follows: 'export LD_LIBRARY_PATH=/usr/local/lib/', but that also didn't help. I even ran the above command using the following (in the 3rd line of the command above):

-vcodec /usr/local/lib/libwebp -lossless 0 -compression_level 6 \

I'm afraid I've reached the limits of my ability to troubleshoot this issue; posting here looking for some help!

[ryandesign (Ryan Carsten Schmidt)]

You don't have to compile webp yourself; there's already a port for it in MacPorts. The maintainers of the ffmpeg port would just have to modify it to use webp.

You should not set LD_LIBRARY_PATH. Any instructions you see advising you to do so are probably for Linux and inapplicable to macOS.