media/capture/video/linux/v4l2_capture_delegate.h

   1 // Copyright 2015 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_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
   6 #define MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
   7
   8 #if defined(OS_OPENBSD)
   9 #include <sys/videoio.h>
  10 #else
  11 #include <linux/videodev2.h>
  12 #endif
  13
  14 #include "base/files/scoped_file.h"
  15 #include "base/memory/ref_counted.h"
  16 #include "media/capture/video/video_capture_device.h"
  17
  18 namespace media {
  19
  20 // Class doing the actual Linux capture using V4L2 API. V4L2 SPLANE/MPLANE
  21 // capture specifics are implemented in derived classes. Created and destroyed
  22 // on the owner's thread, otherwise living and operating on |v4l2_task_runner_|.
  23 class V4L2CaptureDelegate
  24     : public base::RefCountedThreadSafe<V4L2CaptureDelegate> {
  25  public:
  26   // Creates the appropiate VideoCaptureDelegate according to parameters.
  27   static scoped_refptr<V4L2CaptureDelegate> CreateV4L2CaptureDelegate(
  28       const VideoCaptureDevice::Name& device_name,
  29       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
  30       int power_line_frequency);
  31
  32   // Retrieves the #planes for a given |fourcc|, or 0 if unknown.
  33   static size_t GetNumPlanesForFourCc(uint32_t fourcc);
  34   // Returns the Chrome pixel format for |v4l2_fourcc| or PIXEL_FORMAT_UNKNOWN.
  35   static VideoPixelFormat V4l2FourCcToChromiumPixelFormat(
  36       uint32_t v4l2_fourcc);
  37
  38   // Composes a list of usable and supported pixel formats, in order of
  39   // preference, with MJPEG prioritised depending on |prefer_mjpeg|.
  40   static std::list<uint32_t> GetListOfUsableFourCcs(bool prefer_mjpeg);
  41
  42   // Forward-to versions of VideoCaptureDevice virtual methods.
  43   void AllocateAndStart(int width,
  44                         int height,
  45                         float frame_rate,
  46                         scoped_ptr<VideoCaptureDevice::Client> client);
  47   void StopAndDeAllocate();
  48
  49   void SetRotation(int rotation);
  50
  51  protected:
  52   // Class keeping track of SPLANE/MPLANE V4L2 buffers, mmap()ed on construction
  53   // and munmap()ed on destruction. Destruction is syntactically equal for
  54   // S/MPLANE but not construction, so this is implemented in derived classes.
  55   // Internally it has a vector of planes, which for SPLANE will contain only
  56   // one element.
  57   class BufferTracker : public base::RefCounted<BufferTracker> {
  58    public:
  59     BufferTracker();
  60     // Abstract method to mmap() given |fd| according to |buffer|, planarity
  61     // specific.
  62     virtual bool Init(int fd, const v4l2_buffer& buffer) = 0;
  63
  64     uint8_t* const GetPlaneStart(size_t plane) const {
  65       DCHECK_LT(plane, planes_.size());
  66       return planes_[plane].start;
  67     }
  68
  69     size_t GetPlanePayloadSize(size_t plane) const {
  70       DCHECK_LT(plane, planes_.size());
  71       return planes_[plane].payload_size;
  72     }
  73
  74     void SetPlanePayloadSize(size_t plane, size_t payload_size) {
  75       DCHECK_LT(plane, planes_.size());
  76       DCHECK_LE(payload_size, planes_[plane].length);
  77       planes_[plane].payload_size = payload_size;
  78     }
  79
  80    protected:
  81     friend class base::RefCounted<BufferTracker>;
  82     virtual ~BufferTracker();
  83     // Adds a given mmap()ed plane to |planes_|.
  84     void AddMmapedPlane(uint8_t* const start, size_t length);
  85
  86    private:
  87     struct Plane {
  88       uint8_t* start;
  89       size_t length;
  90       size_t payload_size;
  91     };
  92     std::vector<Plane> planes_;
  93   };
  94
  95   V4L2CaptureDelegate(
  96       const VideoCaptureDevice::Name& device_name,
  97       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
  98       int power_line_frequency);
  99   virtual ~V4L2CaptureDelegate();
 100
 101   // Creates the necessary, planarity-specific, internal tracking schemes,
 102   virtual scoped_refptr<BufferTracker> CreateBufferTracker() const = 0;
 103
 104   // Fill in |format| with the given parameters, in a planarity dependent way.
 105   virtual bool FillV4L2Format(v4l2_format* format,
 106                               uint32_t width,
 107                               uint32_t height,
 108                               uint32_t pixelformat_fourcc) const = 0;
 109
 110   // Finish filling |buffer| struct with planarity-dependent data.
 111   virtual void FinishFillingV4L2Buffer(v4l2_buffer* buffer) const = 0;
 112
 113   // Fetch the number of bytes occupied by data in |buffer| and set to
 114   // |buffer_tracker|.
 115   virtual void SetPayloadSize(
 116       const scoped_refptr<BufferTracker>& buffer_tracker,
 117       const v4l2_buffer& buffer) const = 0;
 118
 119   // Sends the captured |buffer| to the |client_|, synchronously.
 120   virtual void SendBuffer(const scoped_refptr<BufferTracker>& buffer_tracker,
 121                           const v4l2_format& format) const = 0;
 122
 123   // A few accessors for SendBuffer()'s to access private member variables.
 124   VideoCaptureFormat capture_format() const { return capture_format_; }
 125   VideoCaptureDevice::Client* client() const { return client_.get(); }
 126   int rotation() const { return rotation_; }
 127
 128  private:
 129   friend class base::RefCountedThreadSafe<V4L2CaptureDelegate>;
 130
 131   // Returns the input |fourcc| as a std::string four char representation.
 132   static std::string FourccToString(uint32_t fourcc);
 133   // VIDIOC_QUERYBUFs a buffer from V4L2, creates a BufferTracker for it and
 134   // enqueues it (VIDIOC_QBUF) back into V4L2.
 135   bool MapAndQueueBuffer(int index);
 136   // Fills all common parts of |buffer|. Delegates to FinishFillingV4L2Buffer()
 137   // for filling in the planar-dependent parts.
 138   void FillV4L2Buffer(v4l2_buffer* buffer, int i) const;
 139   void DoCapture();
 140   void SetErrorState(const std::string& reason);
 141
 142   const v4l2_buf_type capture_type_;
 143   const scoped_refptr<base::SingleThreadTaskRunner> v4l2_task_runner_;
 144   const VideoCaptureDevice::Name device_name_;
 145   const int power_line_frequency_;
 146
 147   // The following members are only known on AllocateAndStart().
 148   VideoCaptureFormat capture_format_;
 149   v4l2_format video_fmt_;
 150   scoped_ptr<VideoCaptureDevice::Client> client_;
 151   base::ScopedFD device_fd_;
 152
 153   // Vector of BufferTracker to keep track of mmap()ed pointers and their use.
 154   std::vector<scoped_refptr<BufferTracker>> buffer_tracker_pool_;
 155
 156   bool is_capturing_;
 157   int timeout_count_;
 158
 159   // Clockwise rotation in degrees. This value should be 0, 90, 180, or 270.
 160   int rotation_;
 161
 162   DISALLOW_COPY_AND_ASSIGN(V4L2CaptureDelegate);
 163 };
 164
 165 }  // namespace media
 166
 167 #endif  // MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_