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* Copyright (C) 2009 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#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 MediaBufferGroup;
class IMediaSource : public IInterface {
enum {
// Maximum number of buffers would be read in readMultiple.
kMaxNumReadMultiple = 128,
// To be called before any other methods on this object, except
// getFormat().
virtual status_t start(MetaData *params = NULL) = 0;
// Any blocking read call returns immediately with a result of NO_INIT.
// It is an error to call any methods other than start after this call
// returns. Any buffers the object may be holding onto at the time of
// the stop() call are released.
// Also, it is imperative that any buffers output by this object and
// held onto by callers be released before a call to stop() !!!
virtual status_t stop() = 0;
// Returns the format of the data output by this media source.
virtual sp<MetaData> getFormat() = 0;
// Options that modify read() behaviour. The default is to
// a) not request a seek
// b) not be late, i.e. lateness_us = 0
struct ReadOptions {
enum SeekMode : int32_t {
// Reset everything back to defaults.
void reset();
void setSeekTo(int64_t time_us, SeekMode mode = SEEK_CLOSEST_SYNC);
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;
void setNonBlocking();
void clearNonBlocking();
bool getNonBlocking() const;
// Used to clear all non-persistent options for multiple buffer reads.
void clearNonPersistent() {
enum Options {
kSeekTo_Option = 1,
uint32_t mOptions;
int64_t mSeekTimeUs;
SeekMode mSeekMode;
int64_t mLatenessUs;
bool mNonBlocking;
// Returns a new buffer of data. Call blocks until a
// buffer is available, an error is encountered or the end of the stream
// is reached.
// End of stream is signalled 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.
// 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, 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 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,
const ReadOptions *options = nullptr) = 0;
// Returns true if |readMultiple| is supported, otherwise false.
virtual bool supportReadMultiple() = 0;
// Returns true if |read| supports nonblocking option, otherwise false.
// |readMultiple| if supported, always allows the nonblocking option.
virtual bool supportNonblockingRead() = 0;
// Causes this source to suspend pulling data from its upstream source
// until a subsequent read-with-seek. Currently only supported by
// OMXCodec.
virtual status_t pause() = 0;
// The consumer of this media source requests that the given buffers
// are to be returned exclusively in response to read calls.
// This will be called after a successful start() and before the
// first read() call.
// Callee assumes ownership of the buffers if no error is returned.
virtual status_t setBuffers(const Vector<MediaBuffer *> & /* buffers */) = 0;
class BnMediaSource: public BnInterface<IMediaSource>
virtual status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply,
uint32_t flags = 0);
virtual status_t pause() {
virtual status_t setBuffers(const Vector<MediaBuffer *> & /* buffers */) {
// TODO: Implement this for local media sources.
virtual status_t readMultiple(
Vector<MediaBuffer *> * /* buffers */, uint32_t /* maxNumBuffers = 1 */,
const ReadOptions * /* options = nullptr */) {
virtual bool supportReadMultiple() {
return false;
// Override in source if nonblocking reads are supported.
virtual bool supportNonblockingRead() {
return false;
static const size_t kBinderMediaBuffers = 4; // buffers managed by BnMediaSource
static const size_t kTransferSharedAsSharedThreshold = 4 * 1024; // if >= shared, else inline
static const size_t kTransferInlineAsSharedThreshold = 64 * 1024; // if >= shared, else inline
static const size_t kInlineMaxTransfer = 256 * 1024; // Binder size limited to BINDER_VM_SIZE.
virtual ~BnMediaSource();
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");
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 {
(void)mMemoryToIndex.emplace(// C++11 mem.get(), std::make_pair(mem, mIndex))
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() {
mIndex = 0;
void gc() {
for (auto it = mMemoryToIndex.begin(); it != mMemoryToIndex.end(); ) {
if (MediaBuffer::isDeadObject(it->second.first)) {
it = mMemoryToIndex.erase(it);
} else {
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