hdmi passthrough sync issue

[Thomas Green]

I have a device that I'm trying to pass hdmi input to hdmi output, and am having trouble with the audio and video gradually going out of sync; the audio starting to lag the video.

It is done with two separate pipelines:

gst-launch-0.10 nv4l2src device=/dev/video1 ! video/x-nv-yuv, width=1920, height=1072, format="(fourcc)I420", framerate="60/1" ! nvvidconv ! video/x-nv-yuv, width=1920, height=1072, format="(fourcc)I420", framerate="60/1" ! nv_omx_videosink hdmi=TRUE sync=TRUE

gst-launch-0.10 alsasrc device=plughw:0,2 do-timestamp=TRUE latency-time=100000 ! audio/x-raw-int, rate=48000, channels=2, width=16, depth=16 ! alsasink device=plughw:0,1 sync=FALSE qos=TRUE

where /dev/video1 is the v4l2 hdmi input device, and plughw:0,2 and plughw:0,1 the alsa hdmi input and out devices respectively.

I've tried to set sync=TRUE on the hdmi audio output to try to keep the audio in sync, but it either never starts sending audio, or after 5 to 15 minutes, the audio stops.

How can I keep the pipelines in sync and playing?


Tom
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[Sebastian Dröge-3]

On Fr, 2016-03-11 at 17:56 +0000, Thomas Green wrote:

> I have a device that I'm trying to pass hdmi input to hdmi output,
> and am having trouble with the audio and video gradually going out of
> sync; the audio starting to lag the video.
>
> It is done with two separate pipelines:
>
> gst-launch-0.10 nv4l2src device=/dev/video1 ! video/x-nv-yuv,
> width=1920, height=1072, format="(fourcc)I420", framerate="60/1" !
> nvvidconv ! video/x-nv-yuv, width=1920, height=1072,
> format="(fourcc)I420", framerate="60/1" ! nv_omx_videosink hdmi=TRUE
> sync=TRUE
>
> gst-launch-0.10 alsasrc device=plughw:0,2 do-timestamp=TRUE latency-
> time=100000 ! audio/x-raw-int, rate=48000, channels=2, width=16,
> depth=16 ! alsasink device=plughw:0,1 sync=FALSE qos=TRUE
>
> where /dev/video1 is the v4l2 hdmi input device, and plughw:0,2 and
> plughw:0,1 the alsa hdmi input and out devices respectively.
>
> I've tried to set sync=TRUE on the hdmi audio output to try to keep
> the audio in sync, but it either never starts sending audio, or after
> 5 to 15 minutes, the audio stops.
>
> How can I keep the pipelines in sync and playing?

By having them in the same pipeline, using sync=true on the sinks and
making sure that the sources and sinks are doing proper clock slaving
to the pipeline clock (and provide proper timestamps).


Note that you're using a 3+ year old version of GStreamer that is no
longer maintained (the 0.10 release series). You won't get much support
for problems with that version, it would be a useful first step to make
sure that you're using a recent GStreamer version.

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


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