[MPlayer-dev-eng] Audio plugins

[Anders Johansson]

Hi,

I have finished the work on the resampling plugin for now. It can
still not do perfect resampling (sometimes you get a small frequency
offset), and it still reduces the amplitude by 2, but I want to do
something else. I will not fix the problem with the frequency offset
unless it is necessary for mencoder cause it is inaudible, but I will
fix the amplitude problem in the future.

There is now a generic FIR filter implemented in MMX and C which could
be used to finish the Dolby Surround decoder (Stephen Davies, you
wrote it do you want to do it or do you want me to do it?) and build
an EQ.


I have revised the audio plugin road map slightly:

1. Remove clicks when forward/backward.

2. Moving the stereo perspective in the room (+3 channels only).

3. Multi channel EQ.

4. Karaoke plugin :)

5. AC3 encoder.

6. Volume control/tools for AC3 streams.

I will also build an application for calibrating the loudspeaker
amplitude and frequency response sometime when I do the EQ.



I also wrote a proposal of how to auto configure the plugins a few
weeks ago but no one responded to it, so here it is again:


I have been thinking of the audio out and how to configure the sound
card and selecting audio plugins depending on format of the audio
stream and the capabilities of the audio device.

I would like to extend the interface to the ao drivers with a new
function called get_capabilities() or something like that. This
function would return a struct containing the limitations of the sound
card. This information could then be used to select the correct audio
decoder and audio plugins in order to maximize the sound quality and
make stuff work automaticly. The scheme would be combined with manual
override. It would also require some changes in the audio plugins or
the audio decoders and in mplayer (to get automatic hw ac3 and mpeg
decoding) if we want everything to auto configure.

Is this a good idea? Please give me your thoughts.


Cheers,
//Anders