<html><head></head><body><div>On Mon, 2017-05-29 at 12:03 -0700, pchaurasia wrote:</div><div><br></div><div>Hi,</div><div><br></div><blockquote type="cite"><div>I am looking to read frames from my Gstreamer pipeline into opencv data structure. I am using 'new_sample' signal of appsink to read frames. The map derived from the sample, read off of appsink - does not seem to give right size of the frame. </div><div><br></div><div> if (!gst_buffer_map ((buffer), &map_info, GST_MAP_READ)) {</div><div> gst_buffer_unmap ((buffer), &map_info);</div><div> gst_sample_unref(sample);</div><div> return GST_FLOW_ERROR;</div><div> }</div><div><br></div><div>I believe map_info.size --> should give size of the frame. The frame size that I see does not appear correct.</div></blockquote><div><br></div><div>How is the size not correct? What frame size in bytes do you get for what resolution in what format, and what did you expect it to be?</div><div><br></div><div>You'll usually want to map video buffers with gst_video_frame_map():</div><div><br></div><div><a href="https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-GstVideoAlignment.html#gst-video-frame-map">https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-GstVideoAlignment.html#gst-video-frame-map</a></div><div><br></div><div>so you also get the stride and such.</div><div><br></div><div>As for Cv::Mat, maybe have a look at the GStreamer OpenCV plugin, there are a bunch of elements that use Cv::Mat as well:</div><div><br></div><div><a href="https://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/ext/opencv">https://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/ext/opencv</a></div><div><br></div><div>Cheers</div><div> -Tim</div><div><br></div><div><span><pre>-- <br></pre><div class="-x-evo-paragraph" style="font-family: monospace; width: 71ch; word-wrap: break-word; word-break: break-word;">Tim Müller, Centricular Ltd - <a href="http://www.centricular.com">http://www.centricular.com</a></div> </span></div></body></html>