Mixing audio with different latency requirements

media/base/audio_latency.h

Index: media/base/audio_latency.h
diff --git a/media/base/audio_latency.h b/media/base/audio_latency.h
new file mode 100644
index 0000000000000000000000000000000000000000..b29df219a96e2c9d7e57e0c1d11fb0daf5f975c3
--- /dev/null
+++ b/media/base/audio_latency.h
@@ -0,0 +1,34 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_BASE_AUDIO_LATENCY_H_
+#define MEDIA_BASE_AUDIO_LATENCY_H_
+
+#include "media/base/media_export.h"
+
+namespace media {
+
+class MEDIA_EXPORT AudioLatency {
+ public:
+  // Categoties of expected latencies for input/output audio.
+  enum LatencyType {
+    LATENCY_EXACT_MS = 0,

[chcunningham, 2016/06/22 04:34:07]

is EXACT planned to be part of the spec? It seems somewhat counter to the way
things settled in https://github.com/WebAudio/web-audio-api/issues/348... ie:
the user agent should be the one to decide. What is the usecase for EXACT?

[o1ka, 2016/06/23 16:36:16]

(The link you gave does not work). Here
https://webaudio.github.io/web-audio-api/#widl-AudioContextOptions-latencyHint
latency can be specified as latency category or a double value in seconds.
Quoting WebAudio folks: The usecase is DAW scenario. Applications that use this,
will be applications that allow users to tweak their settings to get the lowest
possible latency.
The users themselves will be expected to do some work to minimize the risk of
running into glitches (e.g. by not running multiple tabs, close external
processes, make sure extensions aren't running etc).

[chcunningham, 2016/06/27 23:12:25]

Acknowledged.

+    LATENCY_INTERACTIVE,

[chcunningham, 2016/06/22 02:13:56]

Ditto on documenting comments here. To first time reader its not clear how
whether interactive is higher or lower latency than rtc/playback etc. 

[o1ka, 2016/06/23 16:36:16]

Done.

+    LATENCY_RTC,
+    LATENCY_PLAYBACK
+  };
+
+  // |preferred_buffer_size| should be set to 0 if a client has no preference.
+  static int GetHighLatencyBufferSize(int sample_rate,
+                                      int preferred_buffer_size);
+
+  // |hardware_buffer_size| should be set to 0 if unknown/invalid/not preferred.
+  static int GetRtcBufferSize(int sample_rate, int hardware_buffer_size);
+
+  static int GetInteractiveBufferSize(int hardware_buffer_size);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_AUDIO_LATENCY_H_