[PD] pix_buf & pix_snap

[lists at martinmalm.com]

Hi IOhannes,

Thankyou very much for your explanation on this topic :)

cheers /

martin



> Zitiere lists at martinmalm.com:
>
>> Hi !
>>
>> Is there some way to get a 'snapshot' from a videosource (pix_video or
>> pix_film) without using pix_snap ? This does't seem to work with
>> pix_buf
>> since its "only effective if it is storing a static image".
>
> the hint, that [pix_buf] is only effective with static images is a bit
> confusing.
> it means, that copying a whole image each frame from one position in
> memory to
> another is "ineffective". (therefore pix-operations are done in-place if
> possible)
> [pix_snap] does transfer the pixel-data from grafix-card to main-memory,
> which
> is even less effective - a) because you have to do the copying as in
> [pix_buf],
> + b) (more important) because openGL is a client-server machine, that has
> fast
> transfers client2server (eg. setting the state of the rendering engine)
> but
> quite slow transfers server2client (eg. obtaining the rendering-buffer)
> thus [pix_snap] is certainly not what you want.
>
>
> [pix_buf] might be alright, but ít buffers all the new images that arrive,
> so
> you won't be able to get a still-image of a video. (as far as i remember)
>
> the solution might be [pix_buffer]+[pix_buffer_read]+[pix_buffer_write]
> (ok,
> looks a bit clumsy -- shooting with canons at sparrows, as we say in
> austria)
> basically it works like [table]+[tabread]+[tabwrite].
> it is only available with the CVS-version and there should be a basic
> help-file
> somewhere (either in the examples/04.pix (i guess so) or in the reference-
> patches)
>
> since processing is done inline, you will probably have to use an
> additional
> [pix_buf], to be able to process the same image differently...
>
> mfg.a.srd
> IOhannes
>