enable video capture to support sharing across multiple renderer processes

media/video/capture/linux/video_capture_device_linux.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/video/capture/linux/video_capture_device_linux.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/videodev2.h>
 #include <sys/ioctl.h>
@@ skipping 174 matching lines @@
   return device_name_;
 }
 
 void VideoCaptureDeviceLinux::OnAllocate(int width,
                                          int height,
                                          int frame_rate,
                                          EventHandler* observer) {
   DCHECK_EQ(v4l2_thread_.message_loop(), MessageLoop::current());
 
   observer_ = observer;
+  observer_->OnDeviceState(true);

[perkj_chrome, 2011/10/17 08:39:43]

What is the purpose of this? Is it possible to avoid. You know you will have to
change this on all platforms.

[wjia(left Chromium), 2011/10/21 00:56:13]

I am trying to handle the case where observer_ (i.e., VCController) has been
deleted, but device still calls its function. With this signal, manager knows
when to delete controller safely.

[perkj_chrome, 2011/10/21 14:54:00]

We had previously solved this in another way.
Also VideoCapture::Stop is syncronouse. So after calling Stop the device will
not call the VC controller.


On 2011/10/21 00:56:13, wjia wrote:

[wjia(left Chromium), 2011/10/21 23:54:16]

Could you clarify it's VideoCapture::StopCapture or VideoCaptureDevice::Stop,
since VideoCapture::Stop doesn't exist. Neither one is synchronous though. See
media/video/capture/linux/video_capture_device_linux.cc and
content/renderer/media/video_capture_impl.cc.


On 2011/10/21 14:54:00, perkj wrote:

 
   if ((device_fd_ = open(device_name_.unique_id.c_str(), O_RDONLY)) < 0) {
     SetErrorState("Failed to open V4L2 device driver.");
     return;
   }
 
   // Test if this is a V4L2 device.
   v4l2_capability cap;
   if (!((ioctl(device_fd_, VIDIOC_QUERYCAP, &cap) == 0) &&
       (cap.capabilities & V4L2_CAP_VIDEO_CAPTURE))) {
@@ skipping 230 matching lines @@
   r_buffer.memory = V4L2_MEMORY_MMAP;
   r_buffer.count = 0;
 
   if (ioctl(device_fd_, VIDIOC_REQBUFS, &r_buffer) < 0) {
     SetErrorState("Failed to reset buf.");
   }
 
   delete [] buffer_pool_;
   buffer_pool_ = NULL;
   buffer_pool_size_ = 0;
+  observer_->OnDeviceState(false);
 }
 
 void VideoCaptureDeviceLinux::SetErrorState(const std::string& reason) {
   DLOG(ERROR) << reason;
   state_ = kError;
   observer_->OnError();
 }
 
 }  // namespace media