AW: Questions on PREROLL: let 1 buffer pass the sub-pipeline to get PREROLL working

[Maurer, Marie]

Hi Tim,

thanks for the answer. What does async=false change in behavior/flow of data? 

What do I need to change or can save in the code? Or same as before needed?

Best regards,

Marie

-----Ursprüngliche Nachricht-----
Von: gstreamer-devel [mailto:gstreamer-devel-bounces at lists.freedesktop.org] Im Auftrag von Tim Müller
Gesendet: Dienstag, 8. Mai 2018 17:15
An: gstreamer-devel at lists.freedesktop.org
Betreff: Re: Questions on PREROLL: let 1 buffer pass the sub-pipeline to get PREROLL working

On Tue, 2018-05-08 at 14:38 +0000, Maurer, Marie wrote:

Hi Marie,

> I have a single live video pipeline:
>  
> v4l2src -> caps -> tee -> queue -> v4l2sink
>  
> With this pipeline I can change state from NULL to PLAYING and vice 
> versa.
>  
> Now I connect a sub-pipeline to the above tee, where I can create one 
> or more still images from the live video.
> Because I want only one image at a time I let only one buffer pass my 
> sub-pipeline, every time a picture is requested.
> To survive pipeline state changes, I must let pass 1 frame data packet 
> (via a pad probe callback function), otherwise PREROLL does not work 
> and complete pipeline does not go to PLAYING.
>  
> Is this the common way to let 1 buffer pass and drop all others to get 
> PREROLL running? Or is there a better way?

You could try setting async=false on the new sink you add (not to be confused with the "sync" property) where you don't have regular buffer flows.

Cheers
 -Tim

--
Tim Müller, Centricular Ltd - http://www.centricular.com _______________________________________________
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