[pulseaudio-discuss] [RFC] Passthrough support

Colin Guthrie gmane at colin.guthr.ie
Wed Feb 16 15:08:16 PST 2011

'Twas brillig, and Arun Raghavan at 16/02/11 21:24 did gyre and gimble:
> On Wed, 2011-02-16 at 10:39 -0600, pl bossart wrote:
>>>> - I am not sure I understand how/when the query would be used. Seems
>>>> to me like a notification with the formats exposed by the sink
>>>> currently selected would be more usable. And if a change in routing
>>>> happens (new accessory, audio policy, etc), the client is informed and
>>>> can reconfigure to PCM if need be.
>>> In this scheme, how would the client first determine what formats are
>>> available? The notification will also be required - we can either
>>> piggyback in sink, sink-input and card change notifications, or
>>> introduce a new one for a change in available formats (I prefer the
>>> latter).
>> The problem is that you don't know on what sink you will play until
>> you have actually created the pa_stream. The audio policy and routing
>> rules may kick in and if you query before you connect you would end-up
>> with a broken configuration.
> But the query API includes all the information that we can provide at
> stream creation/connect time, so things would only break if the query
> and connect are done with different parameters, or if the sink changed
> in the period between the two calls. It should be possible for clients
> to gracefully handle this and renegotiate.

Just as a "future proofing" comment, what if the routing rules used the
fact the stream was compressed in it's decision making as to which sink
to route it to... ?



Colin Guthrie

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