AudioTrack: relax check on minimum buffer size

Current AudioTrack implementation enforces that the requested audio
buffer size is at least corresponding the audio latency.
This requirement is too strong and leads to problems with current
stagefright and AudioSink implementations when playing over output
streams with long latency.

Ultimately, the AudioSink design should be changed to specify a minimum
buffer size in time or frames units but not in buffer count units.

Change-Id: I8ba603956f92ac49143a8249572665aa548f2f0f

Conflicts:

	media/libmedia/AudioTrack.cpp

Author: Eric Laurent

include/media/AudioTrack.h

@@ -130,8 +130,10 @@ class AudioTrack
      * format:             Audio format (e.g AUDIO_FORMAT_PCM_16_BIT for signed
      *                     16 bits per sample).
      * channelMask:        Channel mask: see audio_channels_t.
-     * frameCount:         Total size of track PCM buffer in frames. This defines the
-     *                     latency of the track.
+     * frameCount:         Minimum size of track PCM buffer in frames. This defines the
+     *                     latency of the track. The actual size selected by the AudioTrack could be
+     *                     larger if the requested size is not compatible with current audio HAL
+     *                     latency.
      * flags:              Reserved for future use.
      * cbf:                Callback function. If not null, this function is called periodically
      *                     to request new PCM data.

media/libmedia/AudioTrack.cpp

@@ -763,12 +763,9 @@ status_t AudioTrack::createTrack_l(
                 mNotificationFramesAct = frameCount/2;
             }
             if (frameCount < minFrameCount) {
-                if (enforceFrameCount) {
-                    LOGE("Invalid buffer size: minFrameCount %d, frameCount %d", minFrameCount, frameCount);
-                    return BAD_VALUE;
-                } else {
-                    frameCount = minFrameCount;
-                }
+                LOGW_IF(enforceFrameCount, "Minimum buffer size corrected from %d to %d",
+                         frameCount, minFrameCount);
+                frameCount = minFrameCount;
             }
         } else {
             // Ensure that buffer alignment matches channelcount