Opus-tools

Opus-tools is a collection of tools for working with opus files currently under development.

Features

• working build system

Encoder

• Robust wav input (steal battle tested code from oggenc, e.g. float and multichannel works)
• Resampling
• bitrate selection
• VBR/CBR/CVBR
• Application selection (audio/voip)
• Mode forcing
• Metadata (emulate oggenc feature set)
• Multichannel
• Muxing delay control (naive usage of libogg will result in 5 second mux delay on silence)
• Not needed in initial release:
  • Replay gain (but it's important as we want players to actually heed it)
  • LPC padding (code for this is very simple, see postfish) but needs some way of setting the prefill inside opus.
  • In CELT_ONLY Switch the last frame size to the smallest size that will fit the remaining samples (reduces padding overhead, makes sure mixed sizes get tested)
  • crop and/or track split arguments (if data outside of the encoded area is available, use that instead of the LPC padding)
  • Exposes all sanely exposable parts of the Opus API (important for testing, even if things are hidden)
  • Flac input (?; code for this is in oggenc)

Decoder

• Resampling
• Multichannel
• metadata display
• Wav output
• audio playback (libao?) or omit and leave for ogg123
• decodes chained files
• Not needed for the initial release:
  • Lookahead limiter (copy from postfish)
  • Dither for 16 bit output