video_decoder.h revision eb525c5499e34cc9c4b825d6d9e75bb07cc06ace 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef REMOTING_CODEC_VIDEO_DECODER_H_
6#define REMOTING_CODEC_VIDEO_DECODER_H_
7
8#include "base/basictypes.h"
9#include "remoting/proto/video.pb.h"
10#include "third_party/skia/include/core/SkRect.h"
11#include "third_party/skia/include/core/SkRegion.h"
12#include "third_party/skia/include/core/SkSize.h"
13
14namespace remoting {
15
16// Interface for a decoder that takes a stream of bytes from the network and
17// outputs frames of data.
18//
19// TODO(ajwong): Beef up this documentation once the API stablizes.
20class VideoDecoder {
21 public:
22  // DecodeResult is returned from DecodePacket() and indicates current state
23  // of the decoder. DECODE_DONE means that last packet for the frame was
24  // processed, and the frame can be displayed now. DECODE_IN_PROGRESS
25  // indicates that the decoder must receive more data before the frame can be
26  // displayed. DECODE_ERROR is returned if there was an error in the stream.
27  enum DecodeResult {
28    DECODE_ERROR = -1,
29    DECODE_IN_PROGRESS,
30    DECODE_DONE,
31  };
32
33  VideoDecoder() {}
34  virtual ~VideoDecoder() {}
35
36  // Initializes the decoder and sets the output dimensions.
37  // |screen size| must not be empty.
38  virtual void Initialize(const SkISize& screen_size) = 0;
39
40  // Feeds more data into the decoder.
41  virtual DecodeResult DecodePacket(const VideoPacket* packet) = 0;
42
43  // Returns true if decoder is ready to accept data via DecodePacket.
44  virtual bool IsReadyForData() = 0;
45
46  virtual VideoPacketFormat::Encoding Encoding() = 0;
47
48  // Marks the specified |region| of the view for update the next time
49  // RenderFrame() is called.  |region| is expressed in |view_size| coordinates.
50  // |view_size| must not be empty.
51  virtual void Invalidate(const SkISize& view_size,
52                          const SkRegion& region) = 0;
53
54  // Copies invalidated pixels within |clip_area| to |image_buffer|. Pixels are
55  // invalidated either by new data received in DecodePacket(), or by explicit
56  // calls to Invalidate(). |clip_area| is specified in |view_size| coordinates.
57  // If |view_size| differs from the source size then the copied pixels will be
58  // scaled accordingly. |view_size| cannot be empty.
59  //
60  // |image_buffer|'s origin must correspond to the top-left of |clip_area|,
61  // and the buffer must be large enough to hold |clip_area| RGBA32 pixels.
62  // |image_stride| gives the output buffer's stride in pixels.
63  //
64  // On return, |output_region| contains the updated area, in |view_size|
65  // coordinates.
66  virtual void RenderFrame(const SkISize& view_size,
67                           const SkIRect& clip_area,
68                           uint8* image_buffer,
69                           int image_stride,
70                           SkRegion* output_region) = 0;
71
72  // Returns the "shape", if any, of the most recently rendered frame.
73  // The shape is returned in source dimensions.
74  virtual const SkRegion* GetImageShape() = 0;
75};
76
77}  // namespace remoting
78
79#endif  // REMOTING_CODEC_VIDEO_DECODER_H_
80