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 "base/memory/scoped_vector.h"
  17 #include "media/capture/video/video_capture_device.h"
  18
  19 namespace media {
  20
  21 // Class doing the actual Linux capture using V4L2 API. V4L2 SPLANE/MPLANE
  22 // capture specifics are implemented in derived classes. Created and destroyed
  23 // on the owner's thread, otherwise living and operating on |v4l2_task_runner_|.
  24 class V4L2CaptureDelegate
  25     : public base::RefCountedThreadSafe<V4L2CaptureDelegate> {
  26  public:
  27   // Creates the appropiate VideoCaptureDelegate according to parameters.
  28   static scoped_refptr<V4L2CaptureDelegate> CreateV4L2CaptureDelegate(
  29       const VideoCaptureDevice::Name& device_name,
  30       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
  31       int power_line_frequency);
  32
  33   // Retrieves the #planes for a given |fourcc|, or 0 if unknown.
  34   static size_t GetNumPlanesForFourCc(uint32_t fourcc);
  35   // Returns the Chrome pixel format for |v4l2_fourcc| or
  36   // VIDEO_CAPTURE_PIXEL_FORMAT_UNKNOWN.
  37   static VideoCapturePixelFormat V4l2FourCcToChromiumPixelFormat(
  38       uint32_t v4l2_fourcc);
  39
  40   // Composes a list of usable and supported pixel formats, in order of
  41   // preference, with MJPEG prioritised depending on |prefer_mjpeg|.
  42   static std::list<uint32_t> GetListOfUsableFourCcs(bool prefer_mjpeg);
  43
  44   // Forward-to versions of VideoCaptureDevice virtual methods.
  45   void AllocateAndStart(int width,
  46                         int height,
  47                         float frame_rate,
  48                         scoped_ptr<VideoCaptureDevice::Client> client);
  49   void StopAndDeAllocate();
  50
  51   void SetRotation(int rotation);
  52
  53  protected:
  54   // Class keeping track of SPLANE/MPLANE V4L2 buffers, mmap()ed on construction
  55   // and munmap()ed on destruction. Destruction is syntactically equal for
  56   // S/MPLANE but not construction, so this is implemented in derived classes.
  57   // Internally it has a vector of planes, which for SPLANE will contain only
  58   // one element.
  59   class BufferTracker : public base::RefCounted<BufferTracker> {
  60    public:
  61     BufferTracker();
  62     // Abstract method to mmap() given |fd| according to |buffer|, planarity
  63     // specific.
  64     virtual bool Init(int fd, const v4l2_buffer& buffer) = 0;
  65
  66     uint8_t* const GetPlaneStart(size_t plane) const {
  67       DCHECK_LT(plane, planes_.size());
  68       return planes_[plane].start;
  69     }
  70
  71     size_t GetPlanePayloadSize(size_t plane) const {
  72       DCHECK_LT(plane, planes_.size());
  73       return planes_[plane].payload_size;
  74     }
  75
  76     void SetPlanePayloadSize(size_t plane, size_t payload_size) {
  77       DCHECK_LT(plane, planes_.size());
  78       DCHECK_LE(payload_size, planes_[plane].length);
  79       planes_[plane].payload_size = payload_size;
  80     }
  81
  82    protected:
  83     friend class base::RefCounted<BufferTracker>;
  84     virtual ~BufferTracker();
  85     // Adds a given mmap()ed plane to |planes_|.
  86     void AddMmapedPlane(uint8_t* const start, size_t length);
  87
  88    private:
  89     struct Plane {
  90       uint8_t* start;
  91       size_t length;
  92       size_t payload_size;
  93     };
  94     std::vector<Plane> planes_;
  95   };
  96
  97   V4L2CaptureDelegate(
  98       const VideoCaptureDevice::Name& device_name,
  99       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
 100       int power_line_frequency);
 101   virtual ~V4L2CaptureDelegate();
 102
 103   // Creates the necessary, planarity-specific, internal tracking schemes,
 104   virtual scoped_refptr<BufferTracker> CreateBufferTracker() const = 0;
 105
 106   // Fill in |format| with the given parameters, in a planarity dependent way.
 107   virtual bool FillV4L2Format(v4l2_format* format,
 108                               uint32_t width,
 109                               uint32_t height,
 110                               uint32_t pixelformat_fourcc) const = 0;
 111
 112   // Finish filling |buffer| struct with planarity-dependent data.
 113   virtual void FinishFillingV4L2Buffer(v4l2_buffer* buffer) const = 0;
 114
 115   // Fetch the number of bytes occupied by data in |buffer| and set to
 116   // |buffer_tracker|.
 117   virtual void SetPayloadSize(
 118       const scoped_refptr<BufferTracker>& buffer_tracker,
 119       const v4l2_buffer& buffer) const = 0;
 120
 121   // Sends the captured |buffer| to the |client_|, synchronously.
 122   virtual void SendBuffer(const scoped_refptr<BufferTracker>& buffer_tracker,
 123                           const v4l2_format& format) const = 0;
 124
 125   // A few accessors for SendBuffer()'s to access private member variables.
 126   VideoCaptureFormat capture_format() const { return capture_format_; }
 127   VideoCaptureDevice::Client* client() const { return client_.get(); }
 128   int rotation() const { return rotation_; }
 129
 130  private:
 131   friend class base::RefCountedThreadSafe<V4L2CaptureDelegate>;
 132
 133   // Returns the input |fourcc| as a std::string four char representation.
 134   static std::string FourccToString(uint32_t fourcc);
 135   // VIDIOC_QUERYBUFs a buffer from V4L2, creates a BufferTracker for it and
 136   // enqueues it (VIDIOC_QBUF) back into V4L2.
 137   bool MapAndQueueBuffer(int index);
 138   // Fills all common parts of |buffer|. Delegates to FinishFillingV4L2Buffer()
 139   // for filling in the planar-dependent parts.
 140   void FillV4L2Buffer(v4l2_buffer* buffer, int i) const;
 141   void DoCapture();
 142   void SetErrorState(const std::string& reason);
 143
 144   const v4l2_buf_type capture_type_;
 145   const scoped_refptr<base::SingleThreadTaskRunner> v4l2_task_runner_;
 146   const VideoCaptureDevice::Name device_name_;
 147   const int power_line_frequency_;
 148
 149   // The following members are only known on AllocateAndStart().
 150   VideoCaptureFormat capture_format_;
 151   v4l2_format video_fmt_;
 152   scoped_ptr<VideoCaptureDevice::Client> client_;
 153   base::ScopedFD device_fd_;
 154
 155   // Vector of BufferTracker to keep track of mmap()ed pointers and their use.
 156   std::vector<scoped_refptr<BufferTracker>> buffer_tracker_pool_;
 157
 158   bool is_capturing_;
 159   int timeout_count_;
 160
 161   // Clockwise rotation in degrees. This value should be 0, 90, 180, or 270.
 162   int rotation_;
 163
 164   DISALLOW_COPY_AND_ASSIGN(V4L2CaptureDelegate);
 165 };
 166
 167 }  // namespace media
 168
 169 #endif  // MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_