Non-blocking audio I/O interface, WIP
Yet another abstraction similar to AudioTrack::Buffer and AudioBufferProvider,
but with support for streaming, non-blocking, and eventually PTS.
This is intended to be used as follows:
- primary HAL output stream implements a Sink
- primary HAL input stream implements a Source
- Pipe implements a Sink
- PipeReader implements a Source or TimedSource (not shown yet),
which supports "read at PTS"
- fast AudioTrack on server side will implement a Source using cblk
- normal AudioTrack on server side will not be changed initially
- fast AudioRecord on server side will implement a Sink using cblk
- normal AudioRecord on server side will not be changed initially
- fast mixer thread will read from Sources and write to a Sink,
or (unlikely) implement a Source and multiple Sinks
- Visualization and PCM logger will read from Source or TimedSource
- A2DP normal mixer will be connected directly to its output stream
and there will be a kind of OutputTrack for duplication that will
read from a Sink with non-blocking write fed by the fast mixer.
Patch set 3 changes:
- Add more implementations of NBAIO interfaces:
added SourceAudioBufferProvider, MonoPipe, MonoPipeReader.
- Added Format_sampleRate and Format_channelCount.
- Extract out the roundUp() method.
- Respond to most comments from previous code review.
- The new classes are untested.
Patch set 4 changes:
- Fix bugs in MonoPipe::write() and MonoPipeReader::read()
- Fix bug initializing mFrameBitShift too early
- renamed roundUp() to roundup()
- Fix Android.mk
- Add LOG_TAG an LOG_NDEBUG, use ALOG_ASSERT and utils/Log.h instead of assert
- Fix build warnings
- Move constructor and destructor bodies from .h to .cpp
- Line length 100
- Following naming conventions for #include double-include protector macros
- Include what you use
- More NBAIO logging
- MonoPipe write can be blocking
Patch set 5 changes:
- Address code review comments
- Use a static library so unused implementations don't take memory
- Comment out libsndfile dependency
- Remove debugging LOGV and LOG_NDEBUG
Patch set 6 changes (would be 6 at old location, actually 2 at new location):
- Address code review comments on patchset 5
- For MonoPipe, allow the full pipe to be used, no need to omit one slot
- Don't do atomic releasing stores unless needed
Still to do:
- I'm not happy with the Pipe class names
- Update build/ for new static library?
Change-Id: Ie6c61f05ce06b676b033be448a8ef9025a2ffcfd
diff --git a/services/audioflinger/AudioBufferProviderSource.cpp b/services/audioflinger/AudioBufferProviderSource.cpp
new file mode 100644
index 0000000..4342171
--- /dev/null
+++ b/services/audioflinger/AudioBufferProviderSource.cpp
@@ -0,0 +1,141 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "AudioBufferProviderSource"
+//#define LOG_NDEBUG 0
+
+#include <cutils/compiler.h>
+#include <utils/Log.h>
+#include "AudioBufferProviderSource.h"
+
+namespace android {
+
+AudioBufferProviderSource::AudioBufferProviderSource(AudioBufferProvider *provider,
+ NBAIO_Format format) :
+ NBAIO_Source(format), mProvider(provider), mConsumed(0)
+{
+ ALOG_ASSERT(provider != NULL);
+ ALOG_ASSERT(format != Format_Invalid);
+}
+
+AudioBufferProviderSource::~AudioBufferProviderSource()
+{
+ if (mBuffer.raw != NULL) {
+ mProvider->releaseBuffer(&mBuffer);
+ }
+}
+
+ssize_t AudioBufferProviderSource::availableToRead()
+{
+ if (CC_UNLIKELY(!mNegotiated)) {
+ return NEGOTIATE;
+ }
+ return mBuffer.raw != NULL ? mBuffer.frameCount - mConsumed : 0;
+}
+
+ssize_t AudioBufferProviderSource::read(void *buffer, size_t count)
+{
+ if (CC_UNLIKELY(!mNegotiated)) {
+ return NEGOTIATE;
+ }
+ if (CC_UNLIKELY(mBuffer.raw == NULL)) {
+ mBuffer.frameCount = count;
+ status_t status = mProvider->getNextBuffer(&mBuffer, AudioBufferProvider::kInvalidPTS);
+ if (status != OK) {
+ return status == NOT_ENOUGH_DATA ? (ssize_t) WOULD_BLOCK : (ssize_t) status;
+ }
+ ALOG_ASSERT(mBuffer.raw != NULL);
+ // mConsumed is 0 either from constructor or after releaseBuffer()
+ }
+ size_t available = mBuffer.frameCount - mConsumed;
+ if (CC_UNLIKELY(count > available)) {
+ count = available;
+ }
+ // count could be zero, either because count was zero on entry or
+ // available is zero, but both are unlikely so don't check for that
+ memcpy(buffer, (char *) mBuffer.raw + (mConsumed << mBitShift), count << mBitShift);
+ if (CC_UNLIKELY((mConsumed += count) >= mBuffer.frameCount)) {
+ mProvider->releaseBuffer(&mBuffer);
+ mBuffer.raw = NULL;
+ mConsumed = 0;
+ }
+ mFramesRead += count;
+ // For better responsiveness with large values of count,
+ // return a short count rather than continuing with next buffer.
+ // This gives the caller a chance to interpolate other actions.
+ return count;
+}
+
+ssize_t AudioBufferProviderSource::readVia(readVia_t via, size_t total, void *user, size_t block)
+{
+ if (CC_UNLIKELY(!mNegotiated)) {
+ return NEGOTIATE;
+ }
+ if (CC_UNLIKELY(block == 0)) {
+ block = ~0;
+ }
+ for (size_t accumulator = 0; ; ) {
+ ALOG_ASSERT(accumulator <= total);
+ size_t count = total - accumulator;
+ if (CC_UNLIKELY(count == 0)) {
+ return accumulator;
+ }
+ if (CC_LIKELY(count > block)) {
+ count = block;
+ }
+ // 1 <= count <= block
+ if (CC_UNLIKELY(mBuffer.raw == NULL)) {
+ mBuffer.frameCount = count;
+ status_t status = mProvider->getNextBuffer(&mBuffer, AudioBufferProvider::kInvalidPTS);
+ if (CC_LIKELY(status == OK)) {
+ ALOG_ASSERT(mBuffer.raw != NULL && mBuffer.frameCount <= count);
+ // mConsumed is 0 either from constructor or after releaseBuffer()
+ continue;
+ }
+ // FIXME simplify logic - does the initial count and block checks again for no reason;
+ // don't you just want to fall through to the size_t available line?
+ if (CC_LIKELY(status == NOT_ENOUGH_DATA)) {
+ status = WOULD_BLOCK;
+ }
+ return accumulator > 0 ? accumulator : (ssize_t) status;
+ }
+ size_t available = mBuffer.frameCount - mConsumed;
+ if (CC_UNLIKELY(count > available)) {
+ count = available;
+ }
+ if (CC_LIKELY(count > 0)) {
+ ssize_t ret = via(user, (char *) mBuffer.raw + (mConsumed << mBitShift), count);
+ if (CC_UNLIKELY(ret <= 0)) {
+ if (CC_LIKELY(accumulator > 0)) {
+ return accumulator;
+ }
+ return ret;
+ }
+ ALOG_ASSERT((size_t) ret <= count);
+ mFramesRead += ret;
+ accumulator += ret;
+ if (CC_LIKELY((mConsumed += ret) < mBuffer.frameCount)) {
+ continue;
+ }
+ }
+ mProvider->releaseBuffer(&mBuffer);
+ mBuffer.raw = NULL;
+ mConsumed = 0;
+ // don't get next buffer until we really need it
+ }
+}
+
+} // namespace android