FFmpeg audio API: Difference between revisions
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* http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2007-November/038323.html | * http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2007-November/038323.html | ||
** Discussion of general ideas and requirements for the new API. | ** Discussion of general ideas and requirements for the new API. | ||
== Down mixing templates == | |||
void ff_downmix_init(DMIXContext, inchannels, outchannels); |
Revision as of 16:44, 15 December 2007
This page is for discussion regarding the reworking of the FFmpeg audio API to accommodate the requirements needed for today's audio codecs.
Features needed
- Generalized channel mixing (SIMD optimized) - users should be able to set their own channel mixing coefficients.
- Codec alterable channel mixing coefficients - the codec should be able to set and update the channel mixing coefficients during runtime (DCA supports this feature, maybe AC-3 also).
- Output channel request function - specify the number of output channels, default should be >2 channels mapped to 2 channels
- Channel reordering - currently there are different orders depending on the codec.
- SIMD optimized interleaving
- Allow planar output - don't duplicate the interleaving code in every codec
- Support bit depths other than 16-bit - 8-bit/24-bit/32-bit/float
- Channel selection - ability to access one channel from a multichannel stream
Feature wish list
- Dolby Pro Logic Surround Sound decoding.
- Add a better FFT routine. (Would the KISS implementation be a good candidate?)
- Fixed point MDCT/FFT implementations
- Custom audio filter support. (Basing it on the video filter API ideas?)
- Proper API for enabling SIMD optimized code.
Current ideas
Threads with previous discussions in the subject:
- http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/47485/focus=48097
- The thread has several ideas already implemented.
- http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2007-November/038323.html
- Discussion of general ideas and requirements for the new API.
Down mixing templates
void ff_downmix_init(DMIXContext, inchannels, outchannels);