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  • #980

Closed
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Opened May 27, 2019 by Mohd Asim@asimfile

decklinkvideosrc: Video freezes when start gstreamer first and attach video input signal later.

Hi,

I am using Blackmagic decklink card to capture video from camera into v4l2 device and use Qt camera and videowidget to display live video.

I am using following pipeline code.

gst-launch-1.0 decklinkvideosrc device-number=0 mode=auto drop-no-signal-frames=true ! deinterlace ! videoscale ! video/x-raw,width=960,height=540 ! videorate max-rate=30 ! videoconvert ! tee ! v4l2sink device=/dev/video0 sync=false

It works fine when attach video input ( ie SDI Cable ) and then execute gstreamer. but when i start gstreamer first and then attach video input,the video freezes for some time. Freeze duration depends on how much time i take to attach cable or start camera.

for eg:-

if attach video after 1 minute from start, the video freezes for 10 sec.

if attach video after 10 minute from start, the video freezes for around 1 minute.

It shows following debug messages during freeze:-

:01:31.681150646 28997 0x7f30fc017cc0 DEBUG decklinkvideosrc gstdecklinkvideosrc.cpp:734:gst_decklink_video_src_update_time_mapping: Calculated new time mapping: pipeline time = 0.999869 * (stream time - 3136466666) + 91057967475 (0.999999) 0:01:31.681189273 28997 0x7f30fc017cc0 DEBUG decklinkvideosrc gstdecklinkvideosrc.cpp:772:gst_decklink_video_src_update_time_mapping: New time mapping causes difference of 0:00:00.000007816 0:01:31.681205106 28997 0x7f30fc017cc0 DEBUG decklinkvideosrc gstdecklinkvideosrc.cpp:774:gst_decklink_video_src_update_time_mapping: Maximum allowed per frame 0:00:00.001668333 0:01:31.681253729 28997 0x7f30fc017cc0 WARN decklinkvideosrc gstdecklinkvideosrc.cpp:869:gst_decklink_video_src_got_frame: Dropped 1 old frames from 0:01:30.891151224 to 0:01:30.891151224 0:01:31.681270033 28997 0x7f30fc017cc0 DEBUG decklinkvideosrc gstdecklinkvideosrc.cpp:893:gst_decklink_video_src_got_frame: Got timecode 01:09:02:03 0:01:31.681287485 28997 0x7f30fc017cc0 DEBUG decklink gstdecklink.cpp:998:VideoInputFrameArrived: Received no audio packet at 0:01:31.058152186 0:01:31.714448541 28997 0x7f30fc017cc0 WARN decklinkvideosrc gstdecklinkvideosrc.cpp:869:gst_decklink_video_src_got_frame: Dropped 1 old frames from 0:01:30.924515091 to 0:01:30.924515091 0:01:31.714474290 28997 0x7f30fc017cc0 DEBUG decklinkvideosrc gstdecklinkvideosrc.cpp:893:gst_decklink_video_src_got_frame: Got timecode 01:09:02:04 0:01:31.714487786 28997 0x7f30fc017cc0 DEBUG decklink gstdecklink.cpp:998:VideoInputFrameArrived: Received no audio packet at 0:01:31.091442529

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Reference: gstreamer/gst-plugins-bad#980