[pulseaudio-discuss] [PATCH v3 05/24] echo-cancel: Canceller may use different spec for playback and capture

Tanu Kaskinen tanuk at iki.fi
Tue Jan 26 03:42:47 PST 2016

On Mon, 2016-01-18 at 13:06 +0530, arun at accosted.net wrote:
> From: Arun Raghavan <git at arunraghavan.net>
> This sets up the default sink sample spec to match what we expect,
> rather than assuming that the canceller will set this up (our assumption
> is that we'll use 32 kHz mono unless someone explicitly overrides this).

I have trouble understanding this description. Maybe rewording is

What does "what we expect" mean? You set the rate and channels to 32
kHz mono, why is that our "expectation"? Does something break if this
expectation is violated via user configuration? The sink and source
rates seem to be configurable (matching rates between source and sink
is enforced, though). The sink channel setup seems to be forced to be
mono, while the source channel map can be configured. What are the
reasons behind this particular mix of configurability and hardcoding?
Some comments about this in the sample spec initialization code might
be a good idea.

I'm not sure why you describe the choice of using 32 kHz mono as an
"assumption". Defaulting to 32 kHz mono is what the code does, in what
way is that an assumption?

Overall, it remains unclear why this change is done.


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