IMediaSource: Improve shared memory buffer transfer
Bug: 29125703
Change-Id: Icf1180dee65f6504e6c10dd4d5b28a8e441f67d1
diff --git a/include/media/IMediaSource.h b/include/media/IMediaSource.h
index 524e7aa..7a7599d 100644
--- a/include/media/IMediaSource.h
+++ b/include/media/IMediaSource.h
@@ -18,14 +18,17 @@
#define IMEDIA_SOURCE_BASE_H_
+#include <map>
+
#include <binder/IInterface.h>
+#include <binder/IMemory.h>
+#include <media/stagefright/MediaBuffer.h>
#include <media/stagefright/MediaErrors.h>
namespace android {
struct MediaSource;
class MetaData;
-class MediaBuffer;
class MediaBufferGroup;
class IMediaSource : public IInterface {
@@ -56,7 +59,7 @@
// a) not request a seek
// b) not be late, i.e. lateness_us = 0
struct ReadOptions {
- enum SeekMode {
+ enum SeekMode : int32_t {
SEEK_PREVIOUS_SYNC,
SEEK_NEXT_SYNC,
SEEK_CLOSEST_SYNC,
@@ -72,6 +75,7 @@
void clearSeekTo();
bool getSeekTo(int64_t *time_us, SeekMode *mode) const;
+ // TODO: remove this if unused.
void setLateBy(int64_t lateness_us);
int64_t getLateBy() const;
@@ -79,6 +83,11 @@
void clearNonBlocking();
bool getNonBlocking() const;
+ // Used to clear all non-persistent options for multiple buffer reads.
+ void clearNonPersistent() {
+ clearSeekTo();
+ }
+
private:
enum Options {
kSeekTo_Option = 1,
@@ -98,21 +107,26 @@
// A result of INFO_FORMAT_CHANGED indicates that the format of this
// MediaSource has changed mid-stream, the client can continue reading
// but should be prepared for buffers of the new configuration.
+ //
+ // TODO: consider removing read() in favor of readMultiple().
virtual status_t read(
MediaBuffer **buffer, const ReadOptions *options = NULL) = 0;
- // Returns a vector of new buffers of data. The vector size could be
- // <= |maxNumBuffers|. Used for buffers with small size
- // since all buffer data are passed back by binder, not shared memory.
+ // Returns a vector of new buffers of data, where the new buffers are added
+ // to the end of the vector.
// Call blocks until an error is encountered, or the end of the stream is
// reached, or format change is hit, or |kMaxNumReadMultiple| buffers have
// been read.
- // End of stream is signalled by a result of ERROR_END_OF_STREAM.
+ // End of stream is signaled by a result of ERROR_END_OF_STREAM.
// A result of INFO_FORMAT_CHANGED indicates that the format of this
// MediaSource has changed mid-stream, the client can continue reading
// but should be prepared for buffers of the new configuration.
+ //
+ // ReadOptions may be specified. Persistent options apply to all reads;
+ // non-persistent options (e.g. seek) apply only to the first read.
virtual status_t readMultiple(
- Vector<MediaBuffer *> *buffers, uint32_t maxNumBuffers = 1) = 0;
+ Vector<MediaBuffer *> *buffers, uint32_t maxNumBuffers = 1,
+ const ReadOptions *options = nullptr) = 0;
// Returns true if |readMultiple| is supported, otherwise false.
virtual bool supportReadMultiple() = 0;
@@ -148,20 +162,92 @@
}
virtual status_t readMultiple(
- Vector<MediaBuffer *> * /* buffers */, uint32_t /* maxNumBuffers = 1 */) {
+ Vector<MediaBuffer *> * /* buffers */, uint32_t /* maxNumBuffers = 1 */,
+ const ReadOptions * /* options = nullptr */) {
return ERROR_UNSUPPORTED;
}
virtual bool supportReadMultiple() {
return false;
}
+
+ static const size_t kBinderMediaBuffers = 4; // buffers managed by BnMediaSource
+
protected:
virtual ~BnMediaSource();
private:
- MediaBufferGroup *mGroup;
-};
+ uint32_t mBuffersSinceStop; // Buffer tracking variable
+ std::unique_ptr<MediaBufferGroup> mGroup;
+
+ // To prevent marshalling IMemory with each read transaction, we cache the IMemory pointer
+ // into a map.
+ //
+ // This is converted into an index, which is used to identify the associated memory
+ // on the receiving side. We hold a reference to the IMemory here to ensure it doesn't
+ // change underneath us.
+
+ struct IndexCache {
+ IndexCache() : mIndex(0) { }
+
+ // Returns the index of the IMemory stored in cache or 0 if not found.
+ uint64_t lookup(const sp<IMemory> &mem) {
+ auto p = mMemoryToIndex.find(mem.get());
+ if (p == mMemoryToIndex.end()) {
+ return 0;
+ }
+ if (MediaBuffer::isDeadObject(p->second.first)) {
+ // this object's dead
+ ALOGW("Attempting to lookup a dead IMemory");
+ (void)mMemoryToIndex.erase(p);
+ return 0;
+ }
+ ALOGW_IF(p->second.first.get() != mem.get(), "Mismatched buffers without reset");
+ return p->second.second;
+ }
+
+ // Returns the index of the IMemory stored in the index cache.
+ uint64_t insert(const sp<IMemory> &mem) {
+ auto p = mMemoryToIndex.find(mem.get());
+ if (p == mMemoryToIndex.end()) {
+ if (mIndex == UINT64_MAX) {
+ ALOGE("Index overflow");
+ mIndex = 1; // skip overflow condition and hope for the best
+ } else {
+ ++mIndex;
+ }
+ (void)mMemoryToIndex.emplace(// C++11 mem.get(), std::make_pair(mem, mIndex))
+ std::piecewise_construct,
+ std::forward_as_tuple(mem.get()), std::forward_as_tuple(mem, mIndex));
+ return mIndex;
+ }
+ ALOGW("IMemory already inserted into cache");
+ return p->second.second;
+ }
+
+ void reset() {
+ mMemoryToIndex.clear();
+ mIndex = 0;
+ }
+
+ void gc() {
+ for (auto it = mMemoryToIndex.begin(); it != mMemoryToIndex.end(); ) {
+ if (MediaBuffer::isDeadObject(it->second.first)) {
+ it = mMemoryToIndex.erase(it);
+ } else {
+ ++it;
+ }
+ }
+ }
+
+ private:
+ uint64_t mIndex;
+ // C++14 unordered_map erase on iterator is stable; C++11 has no guarantee.
+ // Could key on uintptr_t instead of IMemory *
+ std::map<IMemory *, std::pair<sp<IMemory>, uint64_t>> mMemoryToIndex;
+ } mIndexCache;
+};
} // namespace android