// Copyright (c) 2012 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 interface between FFmpeg and Chrome used to proxy FFmpeg's
// read and seek requests to Chrome's internal data structures. The glue works
// through the AVIO interface provided by FFmpeg.
//
// AVIO works through a special AVIOContext created through avio_alloc_context()
// which is attached to the AVFormatContext used for demuxing. The AVIO context
// is initialized with read and seek methods which FFmpeg calls when necessary.
//
// During OpenContext() FFmpegGlue will tell FFmpeg to use Chrome's AVIO context
// by passing NULL in for the filename parameter to avformat_open_input(). All
// FFmpeg operations using the configured AVFormatContext will then redirect
// reads and seeks through the glue.
//
// The glue in turn processes those read and seek requests using the
// FFmpegURLProtocol provided during construction.
//
// FFmpegGlue is also responsible for initializing FFmpeg, which is done once
// per process. Initialization includes: turning off log messages, registering
// a lock manager, and finally registering all demuxers and codecs.
#ifndef MEDIA_FILTERS_FFMPEG_GLUE_H_
#define MEDIA_FILTERS_FFMPEG_GLUE_H_
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "media/base/media_export.h"
#include "media/ffmpeg/ffmpeg_deleters.h"
struct AVFormatContext;
struct AVIOContext;
namespace media {
class MEDIA_EXPORT FFmpegURLProtocol {
public:
// 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;
};
class MEDIA_EXPORT FFmpegGlue {
public:
static void InitializeFFmpeg();
// See file documentation for usage. |protocol| must outlive FFmpegGlue.
explicit FFmpegGlue(FFmpegURLProtocol* protocol);
~FFmpegGlue();
// Opens an AVFormatContext specially prepared to process reads and seeks
// through the FFmpegURLProtocol provided during construction.
bool OpenContext();
AVFormatContext* format_context() { return format_context_; }
private:
bool open_called_;
AVFormatContext* format_context_;
scoped_ptr<AVIOContext, ScopedPtrAVFree> avio_context_;
DISALLOW_COPY_AND_ASSIGN(FFmpegGlue);
};
} // namespace media
#endif // MEDIA_FILTERS_FFMPEG_GLUE_H_