use WAVERFORMATEXTENSIBLE in dsound where possible

[rossb]

WAVERFORMATEXTENSIBLE provides support for >2 channels and >16 bit with DirectSound?. It should be used wherever possible/necessary with a fallback to WAVERFORMATEX if it fails. Richard Dobson has code for this. There are patches in the mailing list archive, or he should be pinged for the latest version.

[rossb]

Some progress has been made on this. PA/DSound now uses WAVEFORMATEXTENSIBLE for multichannel, and contains code (commented out, but which is almost there) for doing non-16 bit. The main work left to do is to handle renegotiation of sample format if the requested format fails (ie if 24 bit is requested, but dsound fails, we need to fall back to 16 bit).

See changesets r1268 r1258 for recent progress on this issue.

[rossb]

See also ticket #54

[rossb]

retired ticket since this issue is now covered by ticket #54