CDD: require timestamps to be accurate to +/- 1 ms
Developers need a reliable and accurate method of obtaining a device's
audio latency so that they can optimize their app's performance for
that device. As it stands there has been insufficient testing with
the "getTimestamp" method of obtaining audio device latency. Adding a
requirement to CDD permits the accuracy of getTimestamp to be tested in
CTS or CTS verifier. The initial strength of requirement is STRONGLY
RECOMMEND. The corresponding test is tracked separately.
Test: CTS or CTS verifier
Bug: 64140129
Change-Id: If569a2f494534e101587e90afb72dc5ce3250bcb
diff --git a/5_multimedia/5_6_audio-latency.md b/5_multimedia/5_6_audio-latency.md
index 7edea1e..cefc797 100644
--- a/5_multimedia/5_6_audio-latency.md
+++ b/5_multimedia/5_6_audio-latency.md
@@ -38,6 +38,10 @@
* **AAudio native audio API**. The set of
[AAudio](https://developer.android.com/ndk/guides/audio/aaudio/aaudio.html) APIs
within [Android NDK](https://developer.android.com/ndk/index.html).
+* **Timestamp**. A pair consisting of a relative frame position within a
+stream and the estimated time when that frame enters or leaves the
+audio processing pipeline on the associated endpoint. See also
+[AudioTimestamp](https://developer.android.com/reference/android/media/AudioTimestamp).
If device implementations declare `android.hardware.audio.output` they are
STRONGLY RECOMMENDED to meet or exceed the following requirements:
@@ -45,6 +49,9 @@
* [SR] Cold output latency of 100 milliseconds or less
* [SR] Continuous output latency of 45 milliseconds or less
* [SR] Minimize the cold output jitter
+* [SR] The output timestamp returned by
+[AudioTrack.getTimestamp](https://developer.android.com/reference/android/media/AudioTrack.html#getTimestamp(android.media.AudioTimestamp))
+and `AAudioStream_getTimestamp` is accurate to +/- 1 ms.
If device implementations meet the above requirements after any initial
calibration when using the OpenSL ES PCM buffer queue API, for continuous output
@@ -67,4 +74,7 @@
* [SR] Cold input latency of 100 milliseconds or less
* [SR] Continuous input latency of 30 milliseconds or less
* [SR] Continuous round-trip latency of 50 milliseconds or less
- * [SR] Minimize the cold input jitter
\ No newline at end of file
+ * [SR] Minimize the cold input jitter
+ * [SR] Limit the error in input timestamps, as returned by
+[AudioRecord.getTimestamp](https://developer.android.com/reference/android/media/AudioRecord.html#getTimestamp(android.media.AudioTimestamp,%20int))
+or `AAudioStream_getTimestamp`, to +/- 1 ms.
