media/base/video_capture_types.h

   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 MEDIA_BASE_VIDEO_CAPTURE_TYPES_H_
   6 #define MEDIA_BASE_VIDEO_CAPTURE_TYPES_H_
   7
   8 #include <vector>
   9
  10 #include "media/base/media_export.h"
  11 #include "ui/gfx/geometry/size.h"
  12
  13 namespace media {
  14
  15 // TODO(wjia): this type should be defined in a common place and
  16 // shared with device manager.
  17 typedef int VideoCaptureSessionId;
  18
  19 // Color formats from camera. This list is sorted in order of preference.
  20 enum VideoPixelFormat {
  21   PIXEL_FORMAT_I420,
  22   PIXEL_FORMAT_YV12,
  23   PIXEL_FORMAT_NV12,
  24   PIXEL_FORMAT_NV21,
  25   PIXEL_FORMAT_UYVY,
  26   PIXEL_FORMAT_YUY2,
  27   PIXEL_FORMAT_RGB24,
  28   PIXEL_FORMAT_ARGB,
  29   PIXEL_FORMAT_MJPEG,
  30   PIXEL_FORMAT_TEXTURE,  // Capture format as a GL texture.
  31   PIXEL_FORMAT_UNKNOWN,  // Color format not set.
  32   PIXEL_FORMAT_MAX,
  33 };
  34
  35 // Policies for capture devices that has source content with dynamic resolution.
  36 enum ResolutionChangePolicy {
  37   // Capture device outputs a fixed resolution all the time. The resolution of
  38   // the first frame is the resolution for all frames.
  39   // It is implementation specific for the capture device to scale, letter-box
  40   // and pillar-box. The only guarantee is that resolution will never change.
  41   RESOLUTION_POLICY_FIXED,
  42
  43   // Capture device outputs frames with dynamic resolution. The width and height
  44   // will not exceed the maximum dimensions specified. The typical scenario is
  45   // the frames will have the same aspect ratio as the original content and
  46   // scaled down to fit inside the limit.
  47   RESOLUTION_POLICY_DYNAMIC_WITHIN_LIMIT,
  48
  49   RESOLUTION_POLICY_LAST,
  50 };
  51
  52 // Some drivers use rational time per frame instead of float frame rate, this
  53 // constant k is used to convert between both: A fps -> [k/k*A] seconds/frame.
  54 const int kFrameRatePrecision = 10000;
  55
  56 // Video capture format specification.
  57 // This class is used by the video capture device to specify the format of every
  58 // frame captured and returned to a client. It is also used to specify a
  59 // supported capture format by a device.
  60 class MEDIA_EXPORT VideoCaptureFormat {
  61  public:
  62   VideoCaptureFormat();
  63   VideoCaptureFormat(const gfx::Size& frame_size,
  64                      float frame_rate,
  65                      VideoPixelFormat pixel_format);
  66
  67   std::string ToString() const;
  68   static std::string PixelFormatToString(VideoPixelFormat format);
  69
  70   // Returns the required buffer size to hold an image of a given
  71   // VideoCaptureFormat with no padding and tightly packed.
  72   size_t ImageAllocationSize() const;
  73
  74   // Checks that all values are in the expected range. All limits are specified
  75   // in media::Limits.
  76   bool IsValid() const;
  77
  78   gfx::Size frame_size;
  79   float frame_rate;
  80   VideoPixelFormat pixel_format;
  81 };
  82
  83 typedef std::vector<VideoCaptureFormat> VideoCaptureFormats;
  84
  85 // Parameters for starting video capture.
  86 // This class is used by the client of a video capture device to specify the
  87 // format of frames in which the client would like to have captured frames
  88 // returned.
  89 class MEDIA_EXPORT VideoCaptureParams {
  90  public:
  91   VideoCaptureParams();
  92
  93   // Requests a resolution and format at which the capture will occur.
  94   VideoCaptureFormat requested_format;
  95
  96   // Policy for resolution change.
  97   ResolutionChangePolicy resolution_change_policy;
  98 };
  99
 100 }  // namespace media
 101
 102 #endif  // MEDIA_BASE_VIDEO_CAPTURE_TYPES_H_