[vlc-devel] Project: Video Barcodes for VLC

Rémi Denis-Courmont remi at remlab.net
Wed Feb 6 18:34:33 CET 2013


Le mercredi 6 février 2013 17:03:12, Sebastian Morr a écrit :
> - Where to put the functionality of barcode-generation? Where does it
>   belong, logically? Is it a filter module or something else?

As Denis already pointed out, a dedicated input thread will be required, with 
its own demuxer and video decoder instances. It wouldn't be the trivial matter 
of inserting a video filter in the existing playlist input thread: such a filter 
can only access pictures just before they are output.

With a dedicated input, there are at least three different ways to model it:
1/ a stream output plugin,
2/ a video filter with the dummy video output behind it,
3/ a video output.
But with just that, you will need to decode the whole video track. as 
explained by Denis.

> - Can you recommend an (image-holding) data structure that allows easy
>   conversion to the different GUIs?

There is the image_handler, maybe. But that's the least of concerns, I think.

> - I need to access the currently open video at arbitrary positions (I'm
>   thinking of building the barcode non-sequentially like an interlaced
>   GIF). Which modules would I need to do this and how are they related?
>   Is there any documentation on the data flow through VLC?

That belongs in the component that will control your dedicated input. That 
does not really fit in any existing abstraction.

That being said, where is this feature provided currently? I somehow suspect 
that it is normally being precomputed offline and passed to the media player as 
some meta-data associated with the media file.

Rémi Denis-Courmont

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