StreamFunc.cpp

/*******************************************************************************
#                                                                              #
# This file is part of uvc2http.                                               #
#                                                                              #
# Copyright (C) 2015 Oleg Efremov                                              #
#                                                                              #
# Uvc_streamer is free software; you can redistribute it and/or modify         #
# it under the terms of the GNU General Public License as published by         #
# the Free Software Foundation; version 2 of the License.                      #
#                                                                              #
# This program is distributed in the hope that it will be useful,              #
# but WITHOUT ANY WARRANTY; without even the implied warranty of               #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                #
# GNU General Public License for more details.                                 #
#                                                                              #
# You should have received a copy of the GNU General Public License            #
# along with this program; if not, write to the Free Software                  #
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA    #
#                                                                              #
*******************************************************************************/

#include "StreamFunc.h"

#include <cstdio>
#include <time.h>

#include "Tracer.h"
#include "UvcGrabber.h"
#include "HttpServer.h"
#include "MjpegUtils.h"

namespace UvcStreamer {
  
  int StreamFunc(const UvcStreamerCfg& config, ShouldExit shouldExit) {
    
    HttpServer httpServer;
    if (!httpServer.Init(config.ServerCfg.ServicePort.c_str())) {
      Tracer::Log("Failed to initialize HTTP server.\n");
      return -2;
    }
    
    // Init and configure UVC video camera
    UvcGrabber uvcGrabber(config.GrabberCfg);
    if (!uvcGrabber.Init()) {
      Tracer::Log("Failed to initialize UvcGrabber (is there a UVC camera?). The app will try to initialize later.\n");
    }
    
    static const long Kilo = 1000;
    
    while (!shouldExit()) {
      
      if (uvcGrabber.IsCameraReady() && !uvcGrabber.IsBroken()) {
        const VideoBuffer* videoBuffer = uvcGrabber.DequeuFrame();
        if (videoBuffer != nullptr) {
            if (!httpServer.QueueBuffer(videoBuffer)) {
              uvcGrabber.RequeueFrame(videoBuffer);
            }
        }
      
        static const long MaxServeTimeMicroSec = (Kilo * Kilo) / config.GrabberCfg.FrameRate / 2;
        httpServer.ServeRequests(MaxServeTimeMicroSec);
        
        // It is safe to sleep for 1 ms. There is no significant 
        // difference (in terms of CPU utilization) in comparison with 
        // sleeping for a rest of time.
        const timespec SleepTime {0, Kilo * Kilo};
        ::nanosleep(&SleepTime, nullptr);

        const VideoBuffer* releasedBuffer = httpServer.DequeueBuffer();
        while (releasedBuffer != nullptr) {
          uvcGrabber.RequeueFrame(releasedBuffer);
        
          releasedBuffer = httpServer.DequeueBuffer();
        }
      }
      else {
        std::vector<const VideoBuffer*> buffers = httpServer.DequeueAllBuffers();
        for (auto buffer : buffers) {
          uvcGrabber.RequeueFrame(buffer);
        }
        
        // Repeat recovery attempts every second.
        const timespec RecoveryDelay {1, 0};
        ::nanosleep(&RecoveryDelay, nullptr);
        
        uvcGrabber.ReInit();
      }
    }
    
    return 0;
  }
}