Gst-launch-1.0 (v1.80) Decklink Interlaced Video

[Sebastian Dröge]

On Fr, 2016-05-20 at 21:30 +0930, Dave Johnstone wrote:
> Hi,
> 
> I am trying to play an SD interlaced file out on a Blackmagic Decklink card but having troubles.  I cannot get the following pipeline to link -
> gst-launch-1.0 uridecodebin uri=file:///Volumes/Video/race.mov ! autovideoconvert ! decklinkvideosink mode=3
> If I deinterlace then interlace with
> 
> uridecodebin uri=file:///Volumes/Video/race.mov ! deinterlace ! autovideoconvert ! interlace field-pattern=2:2 ! videoscale ! videorate ! decklinkvideosink mode=3
> 
> This works but if I add audio

What are the caps the decoder is outputting? Is it marked as
interlaced, why does linking fail exactly? That is, how are the caps
incompatible?

> uridecodebin uri=file:///Volumes/Video/race.mov name=decoder decoder. ! deinterlace ! autovideoconvert ! interlace field-pattern=2:2 ! videoscale ! videorate ! decklinkvideosink mode=3 decoder. ! audioconvert ! decklinkaudiosink
> 
> The audio plays at the correct speed and pitch but stutters as if half the samples are missing.

If you let the video go to a fakesink, and add a videotestsrc in front
of decklinkvideosink, is the audio still stuttering? Is the audio also
stuttering with other audio sinks?

Which version of GStreamer and the decklink plugin are you using?

> What is the correct pipeline for playing interlaced files to a Decklink card in interlaced mode?

You should be able to pass through the interlaced video without
deinterlacing/interlacing, assuming that it is correctly detected as
interlaced content and the resolution and framerate is correct.

> As for HD, even the above trick does not work.

How does HD fail even more?

-- 
Sebastian Dröge, Centricular Ltd · http://www.centricular.com

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