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// 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.
#ifndef MEDIA_BASE_VIDEO_DECODER_H_
#define MEDIA_BASE_VIDEO_DECODER_H_
#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "media/base/media_export.h"
#include "media/base/pipeline_status.h"
#include "ui/gfx/size.h"
namespace media {
class DemuxerStream;
class VideoFrame;
class MEDIA_EXPORT VideoDecoder {
public:
// Status codes for read operations on VideoDecoder.
enum Status {
kOk, // Everything went as planned.
kDecodeError, // Decoding error happened.
kDecryptError // Decrypting error happened.
};
VideoDecoder();
virtual ~VideoDecoder();
// Initializes a VideoDecoder with the given DemuxerStream, executing the
// |status_cb| upon completion.
// |statistics_cb| is used to update the global pipeline statistics.
//
// Note:
// 1) The VideoDecoder will be reinitialized if it was initialized before.
// Upon reinitialization, all internal buffered frames will be dropped.
// 2) This method should not be called during any pending read, reset or stop.
// 3) No VideoDecoder calls except for Stop() should be made before
// |status_cb| is executed.
// 4) DemuxerStream should not be accessed after the VideoDecoder is stopped.
//
// TODO(xhwang): Make all VideoDecoder implementations reinitializable.
// See http://crbug.com/233608
virtual void Initialize(DemuxerStream* stream,
const PipelineStatusCB& status_cb,
const StatisticsCB& statistics_cb) = 0;
// Requests a frame to be decoded. The status of the decoder and decoded frame
// are returned via the provided callback. Only one read may be in flight at
// any given time.
//
// Implementations guarantee that the callback will not be called from within
// this method.
//
// If the returned status is not kOk, some error has occurred in the video
// decoder. In this case, the returned frame should always be NULL.
//
// Otherwise, the video decoder is in good shape. In this case, Non-NULL
// frames contain decoded video data or may indicate the end of the stream.
// NULL video frames indicate an aborted read. This can happen if the
// DemuxerStream gets flushed and doesn't have any more data to return.
typedef base::Callback<void(Status, const scoped_refptr<VideoFrame>&)> ReadCB;
virtual void Read(const ReadCB& read_cb) = 0;
// Resets decoder state, fulfilling all pending ReadCB and dropping extra
// queued decoded data. After this call, the decoder is back to an initialized
// clean state.
// Note: No VideoDecoder calls should be made before |closure| is executed.
virtual void Reset(const base::Closure& closure) = 0;
// Stops decoder, fires any pending callbacks and sets the decoder to an
// uninitialized state. A VideoDecoder cannot be re-initialized after it has
// been stopped.
// Note that if Initialize() has been called, Stop() must be called and
// complete before deleting the decoder.
virtual void Stop(const base::Closure& closure) = 0;
// Returns true if the output format has an alpha channel. Most formats do not
// have alpha so the default is false. Override and return true for decoders
// that return formats with an alpha channel.
virtual bool HasAlpha() const;
// Returns true if the decoder needs bitstream conversion before decoding.
virtual bool NeedsBitstreamConversion() const;
// Returns true if the decoder currently has the ability to decode and return
// a VideoFrame. Most implementations can allocate a new VideoFrame and hence
// this will always return true. Override and return false for decoders that
// use a fixed set of VideoFrames for decoding.
virtual bool HasOutputFrameAvailable() const;
private:
DISALLOW_COPY_AND_ASSIGN(VideoDecoder);
};
} // namespace media
#endif // MEDIA_BASE_VIDEO_DECODER_H_
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