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Diffstat (limited to 'include/media/stagefright/MediaSourceSplitter.h')
-rw-r--r-- | include/media/stagefright/MediaSourceSplitter.h | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/include/media/stagefright/MediaSourceSplitter.h b/include/media/stagefright/MediaSourceSplitter.h new file mode 100644 index 0000000..568f4c2 --- /dev/null +++ b/include/media/stagefright/MediaSourceSplitter.h @@ -0,0 +1,193 @@ +/* + * Copyright (C) 2010 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. + */ + +// This class provides a way to split a single media source into multiple sources. +// The constructor takes in the real mediaSource and createClient() can then be +// used to create multiple sources served from this real mediaSource. +// +// Usage: +// - Create MediaSourceSplitter by passing in a real mediaSource from which +// multiple duplicate channels are needed. +// - Create a client using createClient() and use it as any other mediaSource. +// +// Note that multiple clients can be created using createClient() and +// started/stopped in any order. MediaSourceSplitter stops the real source only +// when all clients have been stopped. +// +// If a new client is created/started after some existing clients have already +// started, the new client will start getting its read frames from the current +// time. + +#ifndef MEDIA_SOURCE_SPLITTER_H_ + +#define MEDIA_SOURCE_SPLITTER_H_ + +#include <media/stagefright/MediaSource.h> +#include <utils/threads.h> +#include <utils/Vector.h> +#include <utils/RefBase.h> + +namespace android { + +class MediaBuffer; +class MetaData; + +class MediaSourceSplitter : public RefBase { +public: + // Constructor + // mediaSource: The real mediaSource. The class keeps a reference to it to + // implement the various clients. + MediaSourceSplitter(sp<MediaSource> mediaSource); + + ~MediaSourceSplitter(); + + // Creates a new client of base type MediaSource. Multiple clients can be + // created which get their data through the same real mediaSource. These + // clients can then be used like any other MediaSource, all of which provide + // data from the same real source. + sp<MediaSource> createClient(); + +private: + // Total number of clients created through createClient(). + int32_t mNumberOfClients; + + // reference to the real MediaSource passed to the constructor. + sp<MediaSource> mSource; + + // Stores pointer to the MediaBuffer read from the real MediaSource. + // All clients use this to implement the read() call. + MediaBuffer *mLastReadMediaBuffer; + + // Status code for read from the real MediaSource. All clients return + // this for their read(). + status_t mLastReadStatus; + + // Boolean telling whether the real MediaSource has started. + bool mSourceStarted; + + // List of booleans, one for each client, storing whether the corresponding + // client's start() has been called. + Vector<bool> mClientsStarted; + + // Stores the number of clients which are currently started. + int32_t mNumberOfClientsStarted; + + // Since different clients call read() asynchronously, we need to keep track + // of what data is currently read into the mLastReadMediaBuffer. + // mCurrentReadBit stores the bit for the current read buffer. This bit + // flips each time a new buffer is read from the source. + // mClientsDesiredReadBit stores the bit for the next desired read buffer + // for each client. This bit flips each time read() is completed for this + // client. + bool mCurrentReadBit; + Vector<bool> mClientsDesiredReadBit; + + // Number of clients whose current read has been completed. + int32_t mNumberOfCurrentReads; + + // Boolean telling whether the last read has been completed for all clients. + // The variable is reset to false each time buffer is read from the real + // source. + bool mLastReadCompleted; + + // A global mutex for access to critical sections. + Mutex mLock; + + // Condition variable for waiting on read from source to complete. + Condition mReadFromSourceCondition; + + // Condition variable for waiting on all client's last read to complete. + Condition mAllReadsCompleteCondition; + + // Functions used by Client to implement the MediaSource interface. + + // If the real source has not been started yet by any client, starts it. + status_t start(int clientId, MetaData *params); + + // Stops the real source after all clients have called stop(). + status_t stop(int clientId); + + // returns the real source's getFormat(). + sp<MetaData> getFormat(int clientId); + + // If the client's desired buffer has already been read into + // mLastReadMediaBuffer, points the buffer to that. Otherwise if it is the + // master client, reads the buffer from source or else waits for the master + // client to read the buffer and uses that. + status_t read(int clientId, + MediaBuffer **buffer, const MediaSource::ReadOptions *options = NULL); + + // Not implemented right now. + status_t pause(int clientId); + + // Function which reads a buffer from the real source into + // mLastReadMediaBuffer + void readFromSource_lock(const MediaSource::ReadOptions *options); + + // Waits until read from the real source has been completed. + // _lock means that the function should be called when the thread has already + // obtained the lock for the mutex mLock. + void waitForReadFromSource_lock(int32_t clientId); + + // Waits until all clients have read the current buffer in + // mLastReadCompleted. + void waitForAllClientsLastRead_lock(int32_t clientId); + + // Each client calls this after it completes its read(). Once all clients + // have called this for the current buffer, the function calls + // mAllReadsCompleteCondition.broadcast() to signal the waiting clients. + void signalReadComplete_lock(bool readAborted); + + // Make these constructors private. + MediaSourceSplitter(); + MediaSourceSplitter(const MediaSourceSplitter &); + MediaSourceSplitter &operator=(const MediaSourceSplitter &); + + // This class implements the MediaSource interface. Each client stores a + // reference to the parent MediaSourceSplitter and uses it to complete the + // various calls. + class Client : public MediaSource { + public: + // Constructor stores reference to the parent MediaSourceSplitter and it + // client id. + Client(sp<MediaSourceSplitter> splitter, int32_t clientId); + + // MediaSource interface + virtual status_t start(MetaData *params = NULL); + + virtual status_t stop(); + + virtual sp<MetaData> getFormat(); + + virtual status_t read( + MediaBuffer **buffer, const ReadOptions *options = NULL); + + virtual status_t pause(); + + private: + // Refernce to the parent MediaSourceSplitter + sp<MediaSourceSplitter> mSplitter; + + // Id of this client. + int32_t mClientId; + }; + + friend class Client; +}; + +} // namespace android + +#endif // MEDIA_SOURCE_SPLITTER_H_ |