Re: [igt-dev] [PATCH i-g-t v3 09/10] tests/kms_chamelium: add a flatline audio test

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 27/05/2019 15:34, Simon Ser wrote:
> This commit adds a flatline test alongside the existing frequencies test.
> 
> The test sends a constant value and checks that the amplitude is correct. A
> window is used to check that each sample is within acceptable bounds. The test
> is stopped as soon as 3 audio pages pass the test.
> 
> Signed-off-by: Simon Ser <simon.ser@intel.com>
> Reviewed-by: Martin Peres <martin.peres@linux.intel.com>
> ---
>   tests/kms_chamelium.c | 101 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 101 insertions(+)
> 
> diff --git a/tests/kms_chamelium.c b/tests/kms_chamelium.c
> index 40ca93687c20..451a616f1a2e 100644
> --- a/tests/kms_chamelium.c
> +++ b/tests/kms_chamelium.c
> @@ -772,6 +772,9 @@ test_display_frame_dump(data_t *data, struct chamelium_port *port)
>   /* A streak of 3 gives confidence that the signal is good. */
>   #define MIN_STREAK 3
>   
> +#define FLATLINE_AMPLITUDE 0.9 /* normalized, ie. in [0, 1] */

I assume the test is making triple sure it only ever outputs this signal 
to connectors connected to Chamelium, in all possible scenarios? (I am 
thinking it could be dangerous to some amps/speakers if by some kind of 
accident.)

Regards,

Tvrtko

> +#define FLATLINE_ACCURACY 0.001 /* ± 0.1% of the full amplitude */
> +
>   /* TODO: enable >48KHz rates, these are not reliable */
>   static int test_sampling_rates[] = {
>   	32000,
> @@ -1138,6 +1141,103 @@ static bool test_audio_frequencies(struct audio_state *state)
>   	return success;
>   }
>   
> +static int audio_output_flatline_callback(void *data, void *buffer,
> +					     int samples)
> +{
> +	struct audio_state *state = data;
> +	double *tmp;
> +	size_t len, i;
> +
> +	len = samples * state->playback.channels;
> +	tmp = malloc(len * sizeof(double));
> +	for (i = 0; i < len; i++)
> +		tmp[i] = FLATLINE_AMPLITUDE;
> +	audio_convert_to(buffer, tmp, len, state->playback.format);
> +	free(tmp);
> +
> +	return state->run ? 0 : -1;
> +}
> +
> +static bool detect_flatline_amplitude(double *buf, size_t buf_len)
> +{
> +	double min, max;
> +	size_t i;
> +	bool ok;
> +
> +	min = max = NAN;
> +	for (i = 0; i < buf_len; i++) {
> +		if (isnan(min) || buf[i] < min)
> +			min = buf[i];
> +		if (isnan(max) || buf[i] > max)
> +			max = buf[i];
> +	}
> +
> +	ok = (min >= FLATLINE_AMPLITUDE - FLATLINE_ACCURACY &&
> +	      max <= FLATLINE_AMPLITUDE + FLATLINE_ACCURACY);
> +	if (ok)
> +		igt_debug("Flatline detected\n");
> +	else
> +		igt_debug("Flatline not detected (min=%f, max=%f)\n",
> +			  min, max);
> +	return ok;
> +}
> +
> +static bool test_audio_flatline(struct audio_state *state)
> +{
> +	bool success;
> +	int32_t *recv;
> +	size_t recv_len, i, channel_len;
> +	int streak, capture_chan;
> +	double *channel;
> +
> +	alsa_register_output_callback(state->alsa,
> +				      audio_output_flatline_callback, state,
> +				      PLAYBACK_SAMPLES);
> +
> +	audio_state_start(state, "flatline");
> +
> +	recv = NULL;
> +	recv_len = 0;
> +	success = false;
> +	while (!success && state->msec < AUDIO_TIMEOUT) {
> +		audio_state_receive(state, &recv, &recv_len);
> +
> +		igt_debug("Detecting audio signal, t=%d msec\n", state->msec);
> +
> +		for (i = 0; i < state->playback.channels; i++) {
> +			capture_chan = state->channel_mapping[i];
> +			igt_assert(capture_chan >= 0);
> +			igt_debug("Processing channel %zu (captured as "
> +				  "channel %d)\n", i, capture_chan);
> +
> +			channel_len = audio_extract_channel_s32_le(NULL, 0,
> +								   recv, recv_len,
> +								   state->capture.channels,
> +								   capture_chan);
> +			channel = malloc(channel_len * sizeof(double));
> +			audio_extract_channel_s32_le(channel, channel_len,
> +						     recv, recv_len,
> +						     state->capture.channels,
> +						     capture_chan);
> +
> +			if (detect_flatline_amplitude(channel, channel_len))
> +				streak++;
> +			else
> +				streak = 0;
> +
> +			free(channel);
> +		}
> +
> +		success = streak == MIN_STREAK * state->playback.channels;
> +	}
> +
> +	audio_state_stop(state, success);
> +
> +	free(recv);
> +
> +	return success;
> +}
> +
>   static bool check_audio_configuration(struct alsa *alsa, snd_pcm_format_t format,
>   				      int channels, int sampling_rate)
>   {
> @@ -1235,6 +1335,7 @@ test_display_audio(data_t *data, struct chamelium_port *port,
>   			audio_state_init(&state, data, alsa, port,
>   					 format, channels, sampling_rate);
>   			success &= test_audio_frequencies(&state);
> +			success &= test_audio_flatline(&state);
>   			audio_state_fini(&state);
>   
>   			alsa_close_output(alsa);
> 
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