Re: AUHAL channel mapping, stream enables, and channel info
Re: AUHAL channel mapping, stream enables, and channel info
- Subject: Re: AUHAL channel mapping, stream enables, and channel info
- From: Doug Wyatt <email@hidden>
- Date: Wed, 3 Nov 2004 09:48:53 -0800
On Nov 2, 2004, at 18:05, Kurt Bigler wrote:
My understanding is that the channel maps provide the method by which
HAL
output (and probably input too) stream enables are controlled when
using the
AUHAL. The AUHAL will disable all streams for which no channels are
mapped.
Please correct me if I'm wrong.
This is correct.
If that's the case, then I also need to have a way to get information
about
the channels of an AUHAL. I haven't seen any specific API for querying
about AUHAL channels, so I take it that one must make some assumptions
and
query device information directly.
Correct.
So for example I think the following is true, and again please correct
if
needed: If no output channel map is specified, then all the channels
of all
the output streams presented by a device are simply concatenated, and
presented in that same order as consecutive channels in the AUHAL.
Correct, with one caveat. If a stream has a format other than
PCM/32-bit native-endian float, it is *ignored* by AUHAL and will not
appear in the flattened channel array.
So in order to disable a certain stream via the AUHAL, I would simply
loop
through all the channels of all the streams of the device, and
determine
which channels in the sequence belong to the stream I want to disable,
and
omit those channels from the channel map. Is that correct?
If your loop also ignores streams other than 32-bit float, correct.
Doug
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