Update comments
We no longer put the filename at start of file.
Change-Id: Ic435b159a23105681e3d4a6cb1ac097bc853302e
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index 11db81b..0f2c323 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -58,8 +58,8 @@
EVENT_BUFFER_END = 5 // Playback head is at the end of the buffer.
};
- /* Create Buffer on the stack and pass it to obtainBuffer()
- * and releaseBuffer().
+ /* Client should declare Buffer on the stack and pass address to obtainBuffer()
+ * and releaseBuffer(). See also callback_t for EVENT_MORE_DATA.
*/
class Buffer
@@ -68,12 +68,16 @@
enum {
MUTE = 0x00000001
};
- uint32_t flags;
+ uint32_t flags; // 0 or MUTE
audio_format_t format; // but AUDIO_FORMAT_PCM_8_BIT -> AUDIO_FORMAT_PCM_16_BIT
// accessed directly by WebKit ANP callback
int channelCount; // will be removed in the future, do not use
- size_t frameCount;
- size_t size;
+
+ size_t frameCount; // number of sample frames corresponding to size;
+ // on input it is the number of frames desired,
+ // on output is the number of frames actually filled
+
+ size_t size; // input/output in byte units
union {
void* raw;
short* i16; // signed 16-bit
@@ -84,15 +88,15 @@
/* As a convenience, if a callback is supplied, a handler thread
* is automatically created with the appropriate priority. This thread
- * invokes the callback when a new buffer becomes available or an underrun condition occurs.
+ * invokes the callback when a new buffer becomes available or various conditions occur.
* Parameters:
*
* event: type of event notified (see enum AudioTrack::event_type).
* user: Pointer to context for use by the callback receiver.
* info: Pointer to optional parameter according to event type:
* - EVENT_MORE_DATA: pointer to AudioTrack::Buffer struct. The callback must not write
- * more bytes than indicated by 'size' field and update 'size' if less bytes are
- * written.
+ * more bytes than indicated by 'size' field and update 'size' if fewer bytes are
+ * written.
* - EVENT_UNDERRUN: unused.
* - EVENT_LOOP_END: pointer to an int indicating the number of loops remaining.
* - EVENT_MARKER: pointer to an uint32_t containing the marker position in frames.
@@ -225,7 +229,7 @@
*/
uint32_t latency() const;
- /* getters, see constructor */
+ /* getters, see constructors and set() */
audio_stream_type_t streamType() const;
audio_format_t format() const;
@@ -401,13 +405,19 @@
status_t attachAuxEffect(int effectId);
/* Obtains a buffer of "frameCount" frames. The buffer must be
- * filled entirely. If the track is stopped, obtainBuffer() returns
+ * filled entirely, and then released with releaseBuffer().
+ * If the track is stopped, obtainBuffer() returns
* STOPPED instead of NO_ERROR as long as there are buffers available,
* at which point NO_MORE_BUFFERS is returned.
* Buffers will be returned until the pool (buffercount())
* is exhausted, at which point obtainBuffer() will either block
* or return WOULD_BLOCK depending on the value of the "blocking"
* parameter.
+ *
+ * Interpretation of waitCount:
+ * +n limits wait time to n * WAIT_PERIOD_MS,
+ * -1 causes an (almost) infinite wait time,
+ * 0 non-blocking.
*/
enum {
@@ -416,12 +426,19 @@
};
status_t obtainBuffer(Buffer* audioBuffer, int32_t waitCount);
+
+ /* Release a filled buffer of "frameCount" frames for AudioFlinger to process. */
void releaseBuffer(Buffer* audioBuffer);
/* As a convenience we provide a write() interface to the audio buffer.
- * This is implemented on top of lockBuffer/unlockBuffer. For best
- * performance use callbacks. Return actual number of bytes written.
- *
+ * This is implemented on top of obtainBuffer/releaseBuffer. For best
+ * performance use callbacks. Returns actual number of bytes written >= 0,
+ * or one of the following negative status codes:
+ * INVALID_OPERATION AudioTrack is configured for shared buffer mode
+ * BAD_VALUE size is invalid
+ * STOPPED AudioTrack was stopped during the write
+ * NO_MORE_BUFFERS when obtainBuffer() returns same
+ * or any other error code returned by IAudioTrack::start() or restoreTrack_l().
*/
ssize_t write(const void* buffer, size_t size);
@@ -448,6 +465,7 @@
AudioTrack& mReceiver;
};
+ // body of AudioTrackThread::threadLoop()
bool processAudioBuffer(const sp<AudioTrackThread>& thread);
status_t createTrack_l(audio_stream_type_t streamType,
uint32_t sampleRate,
@@ -484,7 +502,7 @@
bool mActive; // protected by mLock
- callback_t mCbf;
+ callback_t mCbf; // callback handler for events, or NULL
void* mUserData;
uint32_t mNotificationFramesReq; // requested number of frames between each notification callback
uint32_t mNotificationFramesAct; // actual number of frames between each notification callback