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

From: Simon Ser <simon.ser@intel.com>
To: igt-dev@lists.freedesktop.org
Cc: martin.peres@intel.com
Subject: [igt-dev] [PATCH i-g-t] tests/kms_chamelium: document capture audio buffer size constraints
Date: Fri, 17 May 2019 13:27:09 +0300	[thread overview]
Message-ID: <20190517102709.22026-1-simon.ser@intel.com> (raw)

Explain why we need to choose a big enough buffer for audio capture.

Signed-off-by: Simon Ser <simon.ser@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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