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1 // Copyright 2016 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 // This mojom defines the interface for enumerating Video Capture Devices and | |
6 // selecting one for capturing. Such a VCD is manipulated via creation of a | |
7 // VideoCaptureStream, which is then Start()ed to produce FrameInfos to a | |
8 // VideoCaptureStreamClient. In this sense, this API mimics a UserMediaClient. | |
9 | |
10 module media.mojom; | |
11 | |
12 import "media/mojo/interfaces/media_types.mojom"; | |
13 import "ui/mojo/geometry/geometry.mojom"; | |
14 | |
15 struct VideoCaptureDeviceInfo { | |
16 string device_id; | |
17 string name; | |
18 // TODO(mcasas): add VideoFacingMode facing_mode; | |
19 }; | |
20 | |
21 struct VideoCaptureOptions { | |
22 string device_id; | |
23 | |
24 // Replicate the used fields of VideoCaptureParams. | |
25 mojo.Size capture_size; | |
26 double frame_rate; | |
27 // TODO(mcasas): add and wire PowerLineFrequency and ResolutionChangePolicy. | |
28 }; | |
29 | |
30 // Information provided to a VideoStreamClient about an available video frame. | |
31 struct FrameInfo { | |
32 // Shared memory handle to allocated storage for the frame. This handle may | |
33 // be mapped by the client for read-only access. | |
34 // TODO(mcasas): investigate if sharing this buffer per frame has any impact | |
35 // in performance. If so, reinstaurate a sharing-buffer-preamble. | |
36 handle<shared_buffer> storage_handle; | |
37 // Size in bytes of the allocated storage. | |
38 int32 storage_size; | |
39 | |
40 // Pixel format of the frame data in storage. | |
41 media.interfaces.VideoFormat pixel_format; | |
42 | |
43 // Size of the frame in pixels. This includes pixel data for the whole image; | |
44 // i.e. for YUV formats with subsampled chroma planes where the visible | |
45 // portion does not line up on a sample boundary, |coded_size| will be rounded | |
46 // up appropriately and pixel data will be provided for the odd pixels. | |
47 mojo.Size coded_size; | |
48 | |
49 // Visible rectangle of pixels in the frame. This must be a subrect of | |
50 // |coded_rect|. May be odd with respect to the sample boundaries, e.g. for | |
51 // formats with subsampled chroma. This is used e.g. for letterboxing. | |
52 mojo.Rect visible_rect; | |
53 | |
54 // A coded version of base::TimeTicks::Now() at the time the frame data was | |
55 // generated by its source. For the sake of consistency this must always be | |
56 // interpreted using base::TimeTicks::FromInternalValue or some equivalent. | |
57 int64 timestamp; | |
58 }; | |
59 | |
60 // The client interface for a VideoCaptureStream. | |
61 interface VideoCaptureStreamClient { | |
62 // Informs the client that new frame data is available. |info| provides | |
63 // details about this individual frame. | |
64 OnFrameAvailable(FrameInfo info) => (); | |
65 | |
66 // An error has ocurred; the capture will in all likelihood be interrupted. | |
perkj_chrome
2016/03/07 23:58:27
So to continu the discussion. What is the client s
mcasas
2016/03/08 23:57:28
Yes, you're right. Corrected.
| |
67 OnError(string error); | |
68 }; | |
69 | |
70 // The VideoCaptureStream interface abstracts a distinct local source of video | |
71 // frame data such as a WebCam. | |
72 // TODO(mcasas): Consider extending to desktop capture and web view capture. | |
73 interface VideoCaptureStream { | |
74 // Starts sending frames to |client|. Must only be called once and must be the | |
75 // first call on the Stream. | |
76 Start(VideoCaptureStreamClient client); | |
77 | |
78 // Stops the capture, releasing all associated resources. | |
79 Stop(); | |
80 }; | |
81 | |
82 // Primary top-level service interface exposed by the video_capture component. | |
83 interface VideoCaptureHandler { | |
84 EnumerateDevices() | |
85 => (array<VideoCaptureDeviceInfo> devices); | |
86 | |
87 // TODO(mcasas): Add a method to retrieve the capture capabilities of a given | |
88 // |device_id|. | |
89 | |
90 RequestVideoCaptureStream(VideoCaptureOptions options) | |
91 => (VideoCaptureStream? stream); | |
92 }; | |
93 | |
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