Hi everybody

I attach an improved version of vf_pad.c, thoroughly tested, with a few questions for you.

(1)
On 15 May 2008, at 10:30, Víctor Paesa wrote:
Try sscanf(arg,"%d:%d:%d:%d:%255[^:]:%255[^:]:%d",&a,&b,&c,&d,e,f,&g);

I am having a problem with inputs like

        pad=::::16/9:16

(which should mean "expand to a 16/9 frame mod 16"), because sscanf can't find the %d in between the ::, and so the conversion stops. Ideally the form above should be allowed, lest one needs to ask users to type in clumsy forms with default values as in:

        pad=-1:-1:-1:-1:16/9:16

(which is what the code currently requires). Is there to get sscanf do it? I don't think so. One alternative is to use sscanf to read args one ":" at a time, as I currently do for two of the parameters which can take different forms (aspect and color).

(2) Following up on the above, would a form like

        pad=w=...:h=...:x=...:y=...:a=...:r=...:c=....

be desirable? It'd allow to omit parameters and list them in any order, but for filters with few parameters might be a cumbersome overkill. Eg

        scale=624:368 against scale=w=624:h=368

(3) I have added the possibility of specifying a color for the padding. The structure which lists the colors is taken from vf_drawbox.c. If people like the idea, that can easily be factored out in some avfilter_common file.

(4) The aspect parameter doesn't work as it should for files with SAR different from 1. It's easy to fix, only that the sar information seems unavailable at the filter configuration stage (see the code); I expect Vitor wll be able to help on this one.

(5) I have not resolved the issue of removing memcpy. There is only one call to memcpy in the code; to get rid of it is likely to require some significant change to the avfilter API, that will have to involve Vitor. In these circumstances, I wonder whether it would make sense to commit the code to SOC anyway, and then remove the one call to memcpy when we'll know how. (Observe that this situation is common to several filters.)

Regards,
-vmrsss

Attachment: vf_pad.c
Description: Binary data


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