[alsa-devel] [PATCH] alsabat: add round trip audio latency test

[Takashi Iwai]

On Fri, 03 Jun 2016 04:05:08 +0200,
vivian.zhang at intel.com wrote:
> 
> From: "vivian,zhang" <vivian.zhang at intel.com>
> 
> Audio latency is the time delay as an audio signal passes through
> a system. There are many kinds of audio latency metrics. One useful
> metric is the round trip latency, which is the sum of output latency
> and input latency.
> 
> The measurement step works like below:
> 1. Listen and measure the average loudness of the environment for
> one second;
> 2. Create a threshold value 16 decibels higher than the average
> loudness;
> 3. Begin playing a ~1000 Hz sine wave and start counting the samples
> elapsed;
> 4. Stop counting and playing if the input's loudness is higher than
> the threshold, as the output wave is probably coming back;
> 5. Calculate the audio latency value in milliseconds.
> 
> Signed-off-by: Zhang Vivian <vivian.zhang at intel.com>

Applied now.  Thanks.


Takashi