Missing Plugin for KLV decoder

[Jan Schmidt]

Hi,

On 17/8/21 1:29 am, Giuseppe Gastronome via gstreamer-devel wrote:
> Hi there:
>
> I'm splitting up a video stream into two threads for video display and 
> one for decoding KLV metadata from my pipeline. The stream begins 
> using a udpsrc element and splitting into two threads using a tee 
> element. I'm not sure if I should post how I set up the streams but 
> when I receive the video stream, I get an error that looks like this:
>
> Your GStreamer installation is missing a plug-in.
> ../gst/playback/gstdecodebin2.c(4679):
> gst_decode_bin_expose():/GstPipeline:my_pipeline/GstDecodeBin:decodebin:
> no suitable plugins found:
> Missing decoder: meta/x-klv (meta/x-klv, parsed=(boolean)true)
>
> What behavior can cause this error to happen? I'm pretty sure that I'm 
> using a standard build of GStreamer and so it should have the 
> meta/x-klv plugin.

As mentioned in the other reply, there's no generic decoder for KLV data 
- GStreamer doesn't have a standard metadata stream format that such a 
thing could decode to. It would be good if we did - something that 
converted KLV to a stream of bus messages might be a good model, perhaps.

In order to get decodebin to output the KLV track instead of complaining 
about a missing decoder, you can take a look the 'caps' property. That 
property tells decodebin which caps it should consider as 'raw' caps 
that should be output. If you set it something like 
'caps=video/x-raw(ANY);audio/x-raw(ANY);meta-klv' you'll get raw video 
and audio, and the KLV track contents output on the source pads.

After that, you do unfortunately need to parse the KLV stream manually 
(by feeding it to an appsink and reading buffers out to get the data).

Regards,

Jan.

>
> Thanks.
>
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