Closed Caption 1.16.0 in python

[KPAXIT]

Hello,

I'm trying to use  gst_buffer_get_video_caption_meta () and/or
gst_buffer_set_video_caption_meta (...) on a buffer in python, but I get
error "AttributeError: 'Buffer' object has no attribute
'get_video_caption_meta'
"
info/context:
-Ubuntu 18.04
-Gstreamer 1.16.0 (from source) with base, good, ugly, bad, gst-python
plugins
-pipeline is: videotestsrc is-live=1 ! identity ! x264enc ! mp4mux !
filesink location="file.mp4"

In identity 'handoff' handler i'm trying to get_video_caption_meta () for
example but get an error.

Is it still not supported in python or do I have some python binding issue?

Any help would be appreciated.
Thanks.



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[Mathieu Duponchelle]

Hello,

gst_buffer_get_video_caption_meta() is implemented as a function macro,
and as such is not introspectable. You should be able to use the standard
GstMeta API to access the caption meta however.

There is no gst_buffer_set_video_caption_meta() API, you should however be
able to use GstVideo.buffer_add_video_caption_meta().

On 5/2/19 5:40 PM, KPAXIT wrote:

> Hello,
>
> I'm trying to use  gst_buffer_get_video_caption_meta () and/or
> gst_buffer_set_video_caption_meta (...) on a buffer in python, but I get
> error "AttributeError: 'Buffer' object has no attribute
> 'get_video_caption_meta'
> "
> info/context:
> -Ubuntu 18.04
> -Gstreamer 1.16.0 (from source) with base, good, ugly, bad, gst-python
> plugins
> -pipeline is: videotestsrc is-live=1 ! identity ! x264enc ! mp4mux !
> filesink location="file.mp4"
>
> In identity 'handoff' handler i'm trying to get_video_caption_meta () for
> example but get an error.
>
> Is it still not supported in python or do I have some python binding issue?
>
> Any help would be appreciated.
> Thanks.
>
>
>
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> Sent from: http://gstreamer-devel.966125.n4.nabble.com/
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> gstreamer-devel mailing list
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> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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Mathieu Duponchelle · https://www.centricular.com
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[KPAXIT]

Thank you for your answer.

I'm able to put VideoCaptionMeta on copied buffer, like this
word = ("example text ")
data = word.encode('utf-8')
meta =
GstVideo.buffer_add_video_caption_meta(buff_copy,GstVideo.VideoCaptionType.CEA708_RAW,
data)

but I'm still having hard time to get/read GstVideo.VideoCaptionMeta from a
buffer later on, eg
buff_copy.get_meta(GObject.GType('GstVideoCaptionMetaAPI')) returns Gst.Meta
which contains no data!?

Sorry for my newbie question :/
A main goal is to experiment and see if its possible to inject closed
captions in h264 encoded stream somehow (currently we injecting CC's at
streaming server side and we would like to inject CC's directly when
original stream gets encoded)

PS I'm also tried sending buffers with cc to appsrc and connect it to
ccextractor cccombiner etc but I also don't see any 'caption' pad get linked
and/or used meanwhile recorded file in VLC showing that there are cc tracks
available but none of text is visible. Can appsrc be used with CC meta on
buffers somehow?

Thanks.



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