At Wed, 16 Jan 2008 15:23:37 +0100 (CET), Jaroslav Kysela wrote: > > Hi, > > I am actually thinking to add TLV support to each PCM stream. The > reason is to obtain various "static" information from the driver without > even opening the PCM stream. The current API lack: > > a) get channel info / name / position (e.g. Front Left Speaker) > - not sure how to handle multichannel cards This won't work with the static TLV because the channel mapping is a dynamic information. It varies depending on the hw_params setting. A typical difference is the mappings between 4 and 6 channels (FL/FR/RL/RR and FL/FR/C/LFE/RL/RR). > - I'm sure that this is something to be user configurable Everything is user-configurable :) But the channel mapping is basically bound to the driver implementation, so rather there is no real user-configuration, AFAIK. I've already hacked to extend channel_info to include this information. If you're interested, I'll post patches. > b) get possible channels > c) get possible formats These *could* be dynamic, too. That's why we have a complex hw_params procedure. But, they are static for most cases, so it would likely work. > d) various inter-PCM-device constraint description (e.g. if S/PDIF > PCM stream can be used with analog etc.) This sounds good. Any practical use in mind? > e) eventually more information for device name hinting for userspace > (current problems for HDA, AC97, USB devices are that we have only one > .conf file per driver covering all hardware - we need to detect real > device capabilities and show only devices which can be really used) This would be helpful, too. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
