[libcvd-members] libcvd cvd/videobuffer.h cvd/Linux/v4l1buffer.h...

[Edward Rosten]

CVSROOT:        /cvsroot/libcvd
Module name:    libcvd
Changes by:     Edward Rosten <edrosten>        08/11/28 16:56:12

Modified files:
        cvd            : videobuffer.h 
        cvd/Linux      : v4l1buffer.h v4lbuffer.h 
        progs          : calibrate.cxx 

Log message:
        Initial implementation of Live/Flushable/NotLive semantics for video
        buffers. 

CVSWeb URLs:
http://cvs.savannah.gnu.org/viewcvs/libcvd/cvd/videobuffer.h?cvsroot=libcvd&r1=1.11&r2=1.12
http://cvs.savannah.gnu.org/viewcvs/libcvd/cvd/Linux/v4l1buffer.h?cvsroot=libcvd&r1=1.14&r2=1.15
http://cvs.savannah.gnu.org/viewcvs/libcvd/cvd/Linux/v4lbuffer.h?cvsroot=libcvd&r1=1.11&r2=1.12
http://cvs.savannah.gnu.org/viewcvs/libcvd/progs/calibrate.cxx?cvsroot=libcvd&r1=1.11&r2=1.12

Patches:
Index: cvd/videobuffer.h
===================================================================
RCS file: /cvsroot/libcvd/libcvd/cvd/videobuffer.h,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -b -r1.11 -r1.12
--- cvd/videobuffer.h   28 Aug 2008 06:56:32 -0000      1.11
+++ cvd/videobuffer.h   28 Nov 2008 16:56:04 -0000      1.12
@@ -59,7 +59,25 @@
 class VideoBuffer 
 {
        public:
-               virtual ~VideoBuffer(){}
+               enum Type
+               {
+                       NotLive,
+                       Live,
+                       Flushable
+               };
+               
+               ///Default to the most general semantics
+               VideoBuffer()
+               :m_type(NotLive)
+               {}
+               
+               ///Construct the buffer with the known semantics
+               VideoBuffer(Type _type)
+               :m_type(_type)
+               {}
+
+               virtual ~VideoBuffer()
+               {}
 
                /// The size of the VideoFrames returned by this buffer
                virtual ImageRef size()=0;
@@ -69,7 +87,33 @@
                /// \param f The frame that you are finished with.
                virtual void put_frame(VideoFrame<T>* f)=0;
                /// Is there a frame waiting in the buffer? This function does 
not block. 
+               /// See is_live and is_flushable.
                virtual bool frame_pending()=0;
+
+               /// Returns the type of the video stream
+               ///
+               /// A video with live semantics has frames fed at
+               /// some externally controlled rate, such as from a 
+               /// video camera. 
+               ///
+               /// A stream with live semantics also may be flushable, in
+               /// that all current frames can be removed from the stream
+               /// while frame_pending() is 1, and then the next get_frame()
+               /// will sleep until a frame arrives. This ensures that the 
latency
+               /// is low by discarding any old frames. Buffers flushable in 
this
+               /// manner have a type of VideoBuffer::Type::Flushable.
+               /// 
+               /// Some live streams are not flushable because it is not 
possible
+               /// to determine the state of frame_pending(). These have the 
type
+               /// VideoBuffer::Type::Live, and frame_pending() is always 1.
+               ///
+               /// Otherwise, streams have a type VideoBuffer::Type::NotLive, 
and
+               /// frame_pending is always 1
+               Type type()
+               {
+                       return m_type;
+               }
+
                /// What is the (expected) frame rate of this video buffer, in 
frames per second?               
                virtual double frame_rate()=0;
                /// Go to a particular point in the video buffer (only 
implemented in buffers of recorded video)
@@ -82,6 +126,9 @@
                /// with the same lifetime as the buffer. This is a tool to 
allow management of
                /// this data.
                std::auto_ptr<VideoBufferData> extra_data;
+
+       private:
+               Type m_type;
 };
 
 namespace Exceptions

Index: cvd/Linux/v4l1buffer.h
===================================================================
RCS file: /cvsroot/libcvd/libcvd/cvd/Linux/v4l1buffer.h,v
retrieving revision 1.14
retrieving revision 1.15
diff -u -b -r1.14 -r1.15
--- cvd/Linux/v4l1buffer.h      29 Apr 2008 19:57:54 -0000      1.14
+++ cvd/Linux/v4l1buffer.h      28 Nov 2008 16:56:07 -0000      1.15
@@ -192,12 +192,18 @@
 public:
     /// Construct a video buffer
     /// @param dev file name of the device to use
-    V4L1Buffer(const std::string & dev) : RawV4L1( dev, 
V4L1::cam_type<T>::mode, ImageRef(0,0)) {}
+    V4L1Buffer(const std::string & dev) 
+       :VideoBuffer<T>(VideoBuffer<T>::Flushable),
+        RawV4L1( dev, V4L1::cam_type<T>::mode, ImageRef(0,0)) 
+       {}
 
     /// Construct a video buffer
     /// @param dev file name of the device to use
     /// @param size Size of the video stream to grab
-    V4L1Buffer(const std::string & dev, ImageRef size) : RawV4L1( dev, 
V4L1::cam_type<T>::mode,size ) {}
+    V4L1Buffer(const std::string & dev, ImageRef size) 
+       :VideoBuffer<T>(VideoBuffer<T>::Flushable),
+        RawV4L1( dev, V4L1::cam_type<T>::mode,size ) 
+       {}
 
     virtual ImageRef size()
     {

Index: cvd/Linux/v4lbuffer.h
===================================================================
RCS file: /cvsroot/libcvd/libcvd/cvd/Linux/v4lbuffer.h,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -b -r1.11 -r1.12
--- cvd/Linux/v4lbuffer.h       26 Nov 2008 22:15:43 -0000      1.11
+++ cvd/Linux/v4lbuffer.h       28 Nov 2008 16:56:08 -0000      1.12
@@ -152,7 +152,9 @@
 template <class T> class V4LBuffer : public VideoBuffer<T>
 {
 public:
- V4LBuffer(const std::string & dev, ImageRef size, int input=-1, bool 
fields=false, int frames_per_second=0, bool verbose=0) : devname(dev)
+ V4LBuffer(const std::string & dev, ImageRef size, int input=-1, bool 
fields=false, int frames_per_second=0, bool verbose=0) 
+ :VideoBuffer<T>(VideoBuffer<T>::Flushable), 
+  devname(dev)
     {
        int device = open(devname.c_str(), O_RDWR | O_NONBLOCK);
        if (device == -1)

Index: progs/calibrate.cxx
===================================================================
RCS file: /cvsroot/libcvd/libcvd/progs/calibrate.cxx,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -b -r1.11 -r1.12
--- progs/calibrate.cxx 29 Aug 2008 20:27:33 -0000      1.11
+++ progs/calibrate.cxx 28 Nov 2008 16:56:10 -0000      1.12
@@ -752,7 +752,7 @@
        }
            
        VideoFrame<CAMERA_PIXEL>* vframe = videoBuffer->get_frame();
-       while(videoBuffer->frame_pending())
+       while(videoBuffer->type() == VideoBuffer<CAMERA_PIXEL>::Flushable && 
videoBuffer->frame_pending())
        {
            videoBuffer->put_frame(vframe);
            vframe = videoBuffer->get_frame();