[Ffmpeg-devel] [RFC, PATCH] import libswscale

[Michael Niedermayer]

Hi

On Tue, Mar 21, 2006 at 12:17:23PM +0100, Luca Abeni wrote:
> Hi all,
> 
> Here is a first candidate for importing swscale in the ffmpeg tree.
> 
> Get ffmpeg from CVS, apply my cropping/padding/rescaling patchset, untar
> the attached libswscale.tgz into the ffmpeg directory, and apply the
> attached sws-internal.diff.
> Then, you can configure with "--enable-swscaler --enable-gpl"
> As usual, I did some tests with rescaling, cropping, padding, and pixel
> format conversion, and everything seems to work.
> 
> Some notes/questions:
[...]

> 
> 2) Which interface do we want to use for libswscale? I think we should
> access it through ffmpeg's "img_resample*()" and similar functions (this
> implies that swscale.h will become a private header). Is this ok?

hmm, iam not sure, but its ok for the moment we can change this later

[...]
> 
> 4) There still are many details that should be improved, but I think the
> important thing is to import libswscale in CVS in a short time.
> After that, things can be fixed/improved with small incremental patches.
> For example, right now libswscale depends on libavcodec (for av_malloc,
> av_free, av_log, and similar), but libavcodec depends on libswscale for
> rescaling images. I do not like this kind of "loop dependencies", so
> maybe swscale_glue.c should be moved to libswscale. But I think this can
> be done in a second time.
> Is this acceptable?

yes


[...]

[build system changes left for the build system maintainer]

> Index: ffmpeg/libavcodec/swscaler_glue.c
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ ffmpeg/libavcodec/swscaler_glue.c	2006-03-21 10:04:02.676980744 +0100
> @@ -0,0 +1,149 @@
> +#include "avcodec.h"
> +
> +#include "swscale.h"
> +
> +struct glue_context {
> +    struct SwsContext *ctx;
> +    int h, w;
> +    int topBand, leftBand, topPad, leftPad;
> +    int src_shift[3], dst_shift[3];
> +};
> +
> +/* Choose one of the following:
> +  SWS_FAST_BILINEAR
> +  SWS_BILINEAR
> +  SWS_BICUBIC
> +  SWS_X
> +  SWS_POINT
> +  SWS_AREA
> +  SWS_BICUBLIN
> +  SWS_GAUSS
> +  SWS_SINC
> +  SWS_LANCZOS
> +  SWS_SPLINE
> +*/
> +int sws_flags = SWS_BICUBIC;

uhm, globals ...


> +
> +
> +int img_convert(AVPicture *dst, int dfmt,
> +                const AVPicture *src, int sfmt,
> +                int src_width, int src_height)
> +{
> +    int i;
> +    struct SwsContext *ctx;
> +    uint8_t *s[3];
> +    uint8_t *d[3];
> +    int ss[3], ds[3];

please use a little bit more descriptive variable names, single letters suck


> +
> +    ctx = NULL;
> +
> +    ctx = sws_getContext(src_width, src_height, sfmt, src_width, src_height, dfmt, sws_flags, NULL, NULL, NULL);

setting ctx twice?

[...]

-- 
Michael