Re: [igt-dev] [PATCH i-g-t] tests/kms_chamelium: document capture audio buffer size constraints

[Martin Peres <martin.peres@intel.com>]

On 17/05/2019 13:27, Simon Ser wrote:
> Explain why we need to choose a big enough buffer for audio capture.
> 
> Signed-off-by: Simon Ser <simon.ser@intel.com>

Reviewed-by: Martin Peres <martin.peres@linux.intel.com>
> ---
>  tests/kms_chamelium.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/kms_chamelium.c b/tests/kms_chamelium.c
> index c8b6b22d7b4a..4db604d32cae 100644
> --- a/tests/kms_chamelium.c
> +++ b/tests/kms_chamelium.c
> @@ -924,7 +924,14 @@ do_test_display_audio(data_t *data, struct chamelium_port *port,
> 
>  	/* Needs to be a multiple of 128, because that's the number of samples
>  	 * we get per channel each time we receive an audio page from the
> -	 * Chamelium device. */
> +	 * Chamelium device.
> +	 *
> +	 * Additionally, this value needs to be high enough to guarantee we
> +	 * capture a full period of each sine we generate. If we capture 2048
> +	 * samples at a 192KHz sampling rate, we get a full period for a >94Hz
> +	 * sines. For lower sampling rates, the capture duration will be
> +	 * longer.
> +	 */
>  	channel_len = CAPTURE_SAMPLES;
>  	channel = malloc(sizeof(double) * channel_len);
> 
> --
> 2.21.0
> 
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