HLS video support

[toots]

This PR adds video and mp4 format support to output.file.hls!

TODO:

• Test with ffmpeg.copy
• Test persistence with mp4 format
• Cleanup default ISO codes and bitrate
• Better convention for init segment name

Test script:

set("log.level",5)

source = playlist("~/Documents/playlist")

#source = single("/tmp/bla.mkv")

# To re-encode with liquidsoap internal format:
mpegts = %ffmpeg(
           format="mpegts",
           %audio(
              codec="aac",
              b="128k",
              channels=2,
              ar=44100
           ),
           %video(
             codec="libx264",
             b="5M"
           )
         )

mp4 = %ffmpeg(
        format="mp4",
        movflags="+dash+skip_sidx+skip_trailer+frag_custom",
        frag_duration=10,
        %audio(
          codec="aac",
          b="128k",
          channels=2,
          ar=44100),
        %video(
          codec="libx264",
          b="5M"
        )
      )

# To re-encode with ffmpeg raw frames:
mpegts = %ffmpeg(
           format="mpegts",
           %audio.raw(
              codec="aac",
              b="128k",
              channels=2,
              ar=44100
           ),
           %video.raw(
             codec="libx264",
             b="5M"
           )
         )

mp4 = %ffmpeg(
        format="mp4",
        movflags="+dash+skip_sidx+skip_trailer+frag_custom",
        frag_duration=10,
        %audio.raw(
          codec="aac",
          b="128k",
          channels=2,
          ar=44100),
        %video.raw(
          codec="libx264",
          b="5M"
        )
      )

# To copy without re-encoding:
mpegts = %ffmpeg(
           format="mpegts",
           %audio.copy,
           %video.copy)

mp4 = %ffmpeg(
        format="mp4",
        movflags="+dash+skip_sidx+skip_trailer+frag_custom",
        frag_duration=10,
        %audio.copy,
        %video.copy)

streams = [
  ("mpegts",mpegts),
  ("mp4", mp4)
]

def segment_name(~position,~extname,stream_name) =
  timestamp = int_of_float(time())
  "#{stream_name}_#{timestamp}_#{position}.#{extname}"
end

output.file.hls(playlist="live.m3u8",
                segment_duration=2.0,
                segments=5,
                segments_overhead=5,
                segment_name=segment_name,
                #persist_at="/tmp/state.config",
                "/tmp/hls",
                streams,
                fallible=true,
                source)

[smimram]

Wow great!! :)