On Aug 13 2014 16:06, Clemens Ladisch wrote:
When I wrote the driver, Jay tested which combinations did actually work (without any stream format information command; I don't have the spec), so that's what the driver ended up supporting:
- 6ch at 32/44.1/48/96 kHz
- 2ch at 48/96 kHz
If snd-oxfw also does not send the stream format information command, then I guess that 2ch at 32/44.1 kHz will not work either.
If so, Jey's test included something wrong. I hope someone to test these combinations again, especially 2ch/96kHz.
[...] Instead, we should consider the 2ch modes. This mode seems to be used for Dolby Pro Logic II and Dolby Digital but I don't know about the specification of Dolby something. If we drop these modes, the work to develop OXFW driver becomes simpler.
The driver does not need care about the format itself; the data is just sent as 16-bit words that pretend to be samples. All the driver has to do is to handle the "non-audio" bit in the "IEC958 Playback Default" or "IEC958 Playback PCM Stream" mixer controls; this can be added later.
Hm. So the driver just transfers 2ch 16bit words in IEC 60958 compliant data channels, then the device handles them for surround channels. I misunderstand that Dolby something is a functionality in driver side.
Regards
Takashi Sakamoto (In summer vacation) o-takashi@sakamocchi.jp