Bug Fix: Logitech C930 On Linux Results In Freezing Video [M55]

media/capture/video/linux/v4l2_capture_delegate.cc

 // Copyright 2015 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/capture/video/linux/v4l2_capture_delegate.h"
 
 #include <poll.h>
 #include <sys/fcntl.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
@@ skipping 545 matching lines @@
 
     if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_DQBUF, &buffer)) < 0) {
       SetErrorState(FROM_HERE, "Failed to dequeue capture buffer");
       return;
     }
 
     buffer_tracker_pool_[buffer.index]->set_payload_size(buffer.bytesused);
     const scoped_refptr<BufferTracker>& buffer_tracker =
         buffer_tracker_pool_[buffer.index];
 
-    base::TimeDelta timestamp =
-        base::TimeDelta::FromSeconds(buffer.timestamp.tv_sec) +
-        base::TimeDelta::FromMicroseconds(buffer.timestamp.tv_usec);
-    client_->OnIncomingCapturedData(
-        buffer_tracker->start(), buffer_tracker->payload_size(),
-        capture_format_, rotation_, base::TimeTicks::Now(), timestamp);
+    // There's a wide-spread issue where the kernel does not report accurate,
+    // monotonically-increasing timestamps in the v4l2_buffer::timestamp
+    // field (goo.gl/Nlfamz).
+    // Until this issue is fixed, just use the reference clock as a source of
+    // media timestamps.
+    const base::TimeTicks now = base::TimeTicks::Now();
+    if (first_ref_time_.is_null())
+      first_ref_time_ = now;
+    const base::TimeDelta timestamp = now - first_ref_time_;
+    client_->OnIncomingCapturedData(buffer_tracker->start(),
+                                    buffer_tracker->payload_size(),
+                                    capture_format_, rotation_, now, timestamp);
 
     while (!take_photo_callbacks_.empty()) {
       VideoCaptureDevice::TakePhotoCallback cb =
           std::move(take_photo_callbacks_.front());
       take_photo_callbacks_.pop();
 
       mojom::BlobPtr blob =
           Blobify(buffer_tracker->start(), buffer.bytesused, capture_format_);
       if (blob)
         cb.Run(std::move(blob));
@@ skipping 36 matching lines @@
     DLOG(ERROR) << "Error mmap()ing a V4L2 buffer into userspace";
     return false;
   }
   start_ = static_cast<uint8_t*>(start);
   length_ = buffer.length;
   payload_size_ = 0;
   return true;
 }
 
 }  // namespace media