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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// FFmpegGlue is an adapter for FFmpeg's URLProtocol interface that allows us to
// use a DataSource implementation with FFmpeg. For convenience we use FFmpeg's
// av_open_input_file function, which analyzes the filename given to it and
// automatically initializes the appropriate URLProtocol.
//
// Since the DataSource is already open by time we call av_open_input_file, we
// need a way for av_open_input_file to find the correct DataSource instance.
// The solution is to maintain a map of "filenames" to DataSource instances,
// where filenames are actually just a unique identifier. For simplicity,
// FFmpegGlue is registered as an HTTP handler and generates filenames based on
// the memory address of the DataSource, i.e., http://0xc0bf4870. Since there
// may be multiple FFmpegDemuxers active at one time, FFmpegGlue is a
// thread-safe singleton.
//
// Usage: FFmpegDemuxer adds the DataSource to FFmpegGlue's map and is given a
// filename to pass to av_open_input_file. FFmpegDemuxer calls
// av_open_input_file with the filename, which results in FFmpegGlue returning
// the DataSource as a URLProtocol instance to FFmpeg. Since FFmpegGlue is only
// needed for opening files, when av_open_input_file returns FFmpegDemuxer
// removes the DataSource from FFmpegGlue's map.
#ifndef MEDIA_FILTERS_FFMPEG_GLUE_H_
#define MEDIA_FILTERS_FFMPEG_GLUE_H_
#include <map>
#include <string>
#include "base/memory/singleton.h"
#include "base/synchronization/lock.h"
#include "media/base/media_export.h"
struct URLProtocol;
namespace media {
class MEDIA_EXPORT FFmpegURLProtocol {
public:
FFmpegURLProtocol() {}
virtual ~FFmpegURLProtocol() {}
// Read the given amount of bytes into data, returns the number of bytes read
// if successful, kReadError otherwise.
virtual int Read(int size, uint8* data) = 0;
// Returns true and the current file position for this file, false if the
// file position could not be retrieved.
virtual bool GetPosition(int64* position_out) = 0;
// Returns true if the file position could be set, false otherwise.
virtual bool SetPosition(int64 position) = 0;
// Returns true and the file size, false if the file size could not be
// retrieved.
virtual bool GetSize(int64* size_out) = 0;
// Returns false if this protocol supports random seeking.
virtual bool IsStreaming() = 0;
private:
DISALLOW_COPY_AND_ASSIGN(FFmpegURLProtocol);
};
class MEDIA_EXPORT FFmpegGlue {
public:
// Returns the singleton instance.
static FFmpegGlue* GetInstance();
// Adds a FFmpegProtocol to the FFmpeg glue layer and returns a unique string
// that can be passed to FFmpeg to identify the data source.
std::string AddProtocol(FFmpegURLProtocol* protocol);
// Removes a FFmpegProtocol from the FFmpeg glue layer. Using strings from
// previously added FFmpegProtocols will no longer work.
void RemoveProtocol(FFmpegURLProtocol* protocol);
// Assigns the FFmpegProtocol identified with by the given key to
// |protocol|, or assigns NULL if no such FFmpegProtocol could be found.
void GetProtocol(const std::string& key,
FFmpegURLProtocol** protocol);
private:
// Only allow Singleton to create and delete FFmpegGlue.
friend struct DefaultSingletonTraits<FFmpegGlue>;
FFmpegGlue();
virtual ~FFmpegGlue();
// Returns the unique key for this data source, which can be passed to
// av_open_input_file as the filename.
std::string GetProtocolKey(FFmpegURLProtocol* protocol);
// Mutual exclusion while adding/removing items from the map.
base::Lock lock_;
// Map between keys and FFmpegProtocol references.
typedef std::map<std::string, FFmpegURLProtocol*> ProtocolMap;
ProtocolMap protocols_;
friend class FFmpegGlueTest;
static URLProtocol* url_protocol();
DISALLOW_COPY_AND_ASSIGN(FFmpegGlue);
};
} // namespace media
#endif // MEDIA_FILTERS_FFMPEG_GLUE_H_