From XiphWiki
Revision as of 05:39, 30 October 2005 by Saoshyant (Talk | contribs) (Ogg Vorbis Bitrate Peeling: this should have been fixed quite a while ago)

Jump to: navigation, search

These are proposed bounty projects, similar to or the Ghostscript bug bounty program. We don't have the same level of funding but could start a pot with $10-$100 and let people contribute to specific bounties through paypal.

It would be helpful to list $ amounts which have been donated for each bounty, even if the foundation hasn't decided how much extra (if any) to allocate. --Tesseract

OggVorbis 5.1

5.1 Sound encoding in Ogg Vorbis.

There are two steps here. Simple coupling and lowpass for the .1 channel, and a full set of tuned modes. They should be separate bounties.

This should be implemented with ambisonics as the internally coupled channels, and then use ambisonic g-format filters for en/dec coding from and to 5.1. This will allow correct playback on many different speaker layouts and an easy path to headphone support.

Xiph Quicktime Plugin

(See here for more info on this project: [1])

You have to write a Quicktime Plugin for the Ogg container and the Xiph Codec Family. qtcomponents provides support for Ogg Vorbis and MNG. This could be used as start. Xiph Quicktime Plugin has to support encoding/decoding for:

  • Ogg Media container
    • qtcomponents has an operational pluggable API for import, it needs some work to be long term supportable. It does not have a pluggable API for exporting at this time.
  • Support for Chained Ogg Streams
    • qtcomponents imports chained files as multiple tracks in QuickTime. It does not create chained files during export.
  • Support for Icecast Streams (sending is optional)
    • qtcomponents implements nothing towards this item. First up is a reverse-engineering effort, as the specifications for a streaming media handler have not been published.
  • Support for Xiph Codec Family: Vorbis, Theora, FLAC, Speex, Writ

It must also be possible to use the Xiph codecs in .mov files in combination with other quicktime codecs.

  • qtcomponents supports embedding media encoded with Xiph codes into .mov files.

The plugin should work with at least QuickTime 6.x and 7.x on Mac OS X and Windows. (Mac OS 9 would be nice but probably isn't as important.)

All work must be released under the GPL.

Aggressive low-bitrate libvorbis encoding improvements for Vorbis I

libvorbis has a lot of room for improvement in all quality/bitrate departments, particularly at the lower quality levels / bitrates. There are many directions to approach this problem from.

To claim this bounty, the following criteria would have to be met:

  • A 25%-or-better reduction in bitrate for quality levels -1, 0, 1 on a reasonable testsuite while maintaining qualitative equivilence (or improvement) in community testing.
  • No overall qualitative/bitrate regressions in quality levels 2 upwards
  • Output ogg files compatible with Vorbis I spec
  • Changes under suitable license for re-integration with Xiph.Org libvorbis

iPod playback support

The Linux on iPod project has vorbis decode working (with alternate firmware) at a good fraction of realtime. It should be a small matter of optimization to get it working for useful playback.

FLAC support in libfishsound

libfishsound currently only supports Ogg Vorbis and Ogg Speex. It should be extended to support FLAC to complete the set of Xiph audio codecs.

Ogg Vorbis Bitrate Peeling

Note: a bounty for this project has been posted on Add bitrate peeling to the standard libvorbis encoding library.

Ogg Vorbis bitrate peeling has been a topic brought up time and again to combat MP3 enthusiasts. But this feature does not actually exist, only the mere possibility abounds. This bounty is set to change that.

The peeler must meet the following criteria:

  • Any Vorbis stream can be converted (not transcoded) to a lower quality setting
  • Resulting streams would be identical or nearly identical to a stream generated by encoding the original source to the selected quality
  • This process is reasonably fast (that is, signifigantly faster than re-encoding from source)

The following must also be accomplished to claim this bounty:

  • The encoding libraries must be updated to create peelable Vorbis streams natively
  • Old Vorbis streams must be peelable already, or convertable with a utility in order to be made peelable
  • If older streams are not natively peelable, old unpeelable Vorbis streams must be identifiable and discernable from peelable streams in such a way as to facilitate transcoding streams from the old format
  • All work submitted must be licenced under a BSD style licence (excepting circumstances where other licences may conflict)