Extraction of overlay data from stored video

[PRADEEP NALAWADE]

How to overlay a text onto the h264 stream and store it using GStreamer so that overlay text can be extracted later. I need to extract the overlay text from the video.

I am using the following command to overlay text onto the stream and store it.

gst-launch-1.0 -e imxv4l2videosrc ! textoverlay text="Sample Video" valignment=position halignment=position xpos=1 ypos=1 font-desc="Sans, 20" ! timeoverlay ! vpuenc_h264 ! matroskamux ! filesink location=video.mp4

Is it possible to extract the text overlay from the video generated using above command? If not, how to overlay a text, so that it can be extracted later?

Thanks in advance.

Pradeep Nalawade

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[Digits]

You could add your text on an alpha channel, this will keep it separate from the actual video content but carried with it in sync.  Downside is only a few video formats support the alpha channel such as ProRes4444 and Quicktime Animation Codec.

Regards,

Dave.

[PRADEEP NALAWADE]

Thanks Dave for your reply.

I am new to the GStreamer, so can you please provide me the pipeline to
overlay a text onto to the video and pipeline to extract the overlay
from the video.

Thanks in advance.

Regards,

Pradeep

On Thursday 29 December 2016 05:45 AM, Digits wrote:

> You could add your text on an alpha channel, this will keep it separate from
> the actual video content but carried with it in sync.  Downside is only a
> few video formats support the alpha channel such as ProRes4444 and Quicktime
> Animation Codec.
>
> Regards,
>
> Dave.
>
>
>
> --
> View this message in context: http://gstreamer-devel.966125.n4.nabble.com/Extraction-of-overlay-data-from-stored-video-tp4681266p4681282.html
> Sent from the GStreamer-devel mailing list archive at Nabble.com.
> _______________________________________________
> gstreamer-devel mailing list
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[Nicolas Dufresne-5]

Le 28 déc. 2016 12:41 AM, "PRADEEP NALAWADE" <[hidden email]> a écrit :

How to overlay a text onto the h264 stream and store it using GStreamer so that overlay text can be extracted later. I need to extract the overlay text from the video.

I am using the following command to overlay text onto the stream and store it.

gst-launch-1.0 -e imxv4l2videosrc ! textoverlay text="Sample Video" valignment=position halignment=position xpos=1 ypos=1 font-desc="Sans, 20" ! timeoverlay ! vpuenc_h264 ! matroskamux ! filesink location=video.mp4

Is it possible to extract the text overlay from the video generated using above command? If not, how to overlay a text, so that it can be extracted later?

Thanks in advance.

The pipeline you are using render the overlay directly on the image. It is not possible to extract it afterward. What you could do instead is to use a subtitle stream.

Nicolas

Pradeep Nalawade

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