[FFmpeg-devel] [PATCH] swscale: add API to convert AVFrames directly
Michael Niedermayer
michaelni at gmx.at
Mon Sep 30 17:39:37 CEST 2013
On Sun, Sep 29, 2013 at 08:21:35PM +0200, wm4 wrote:
> On Sun, 29 Sep 2013 17:50:52 +0200
> Michael Niedermayer <michaelni at gmx.at> wrote:
[...]
> >
> >
> > > diff --git a/libswscale/swscale.h b/libswscale/swscale.h
> > > index 42702b7..60733f0 100644
> > > --- a/libswscale/swscale.h
> > > +++ b/libswscale/swscale.h
> > > @@ -39,6 +39,8 @@
> > > #include "libavutil/pixfmt.h"
> > > #include "version.h"
> > >
> > > +struct AVFrame;
> > > +
> > > /**
> > > * Return the LIBSWSCALE_VERSION_INT constant.
> > > */
> > > @@ -169,6 +171,81 @@ struct SwsContext *sws_alloc_context(void);
> > > int sws_init_context(struct SwsContext *sws_context, SwsFilter *srcFilter, SwsFilter *dstFilter);
> > >
> > > /**
> > > + * Set source filter. This works only with sws_reinit_cached_context() and
> > > + * sws_scale_frame().
> > > + *
> > > + * @return zero or positive value on success, a negative value on
> > > + * error
> > > + */
> > > +int sws_set_src_filter(struct SwsContext *sws_context, SwsFilter *srcFilter);
> > > +
> > > +/**
> > > + * Set destination filter. This works only with sws_reinit_cached_context() and
> > > + * sws_scale_frame().
> > > + *
> > > + * @return zero or positive value on success, a negative value on
> > > + * error
> > > + */
> > > +int sws_set_dst_filter(struct SwsContext *sws_context, SwsFilter *dstFilter);
> >
> > would it make sense to allow seting the filter via AVOption as a
> > char* ?
> > iam wondering because this maybe would avoid these 2 functions
>
> SwsFilter is a struct with 4 SwsVector members, so I'm not sure how
> that would work. Also, I need to know if the filter changes. These
> functions basically set a flag that they changed, and if they use the
> AVOption API, I'd have to compare the SwsFilters with the old state to
> detect a change.
the char * string could allow something like
"1,2,1" (simple lowpass applied to luma & chroma & horizontal and vertical)
"v:1,2,1" same lowpass applied only to vertical luma & chroma that is poor deinterlace
"lh:0,0,1,ch:0,0.5,0.5" horizontal shift luma by 1 pixelm chroma by half a pixel
thats just a quick and random idea for a syntax and probably a bit of topic
so its more for consideration of future design direction ...
one advantage of such string based system with AVOptions is that it
shouldnt require any specific code in a user application that supports
avoptions
>
> >
> > [...]
> > > +static void sws_set_src_frame_options(struct SwsContext *c, struct AVFrame *src)
> > > +{
> > > + c->srcFormat = src->format;
> > > + c->srcW = src->width;
> > > + c->srcH = src->height;
> > > + c->srcRange = src->color_range;
> > > + sws_set_avframe_colorspace_table(c->srcColorspaceTable, src->colorspace);
> > > +}
> > > +
> > > +static void sws_set_dst_frame_options(struct SwsContext *c, struct AVFrame *dst)
> > > +{
> > > + c->dstFormat = dst->format;
> > > + c->dstW = dst->width;
> > > + c->dstH = dst->height;
> > > + c->dstRange = dst->color_range;
> > > + sws_set_avframe_colorspace_table(c->dstColorspaceTable, dst->colorspace);
> > > +}
> >
> > static functions dont need sws_ prefixes, if you want to shorten them
>
> I removed it from some functions. I left it for others, because maybe
> they should actually be public.
>
> By the way, I'm not all that sure whether my patch is correct.
> libswscale is very scary, and there could be some things I missed. In
> particular, there's the question whether sws_uninit_context followed
> sws_init_context really does full reinitialization, or if there are
> additional members that must be reset in sws_uninit_context. (Members
> which are set only by some init code paths, but are read by everything
> would belong into this category.)
you could try to memset the context to some non 0 value on alloc
and clear just the values from uninit and then try fate
[...]
> options.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> ca2e03fcb8ed9b12e9a96e1d3e97e238dcdf9eff 0001-swscale-make-bilinear-scaling-the-default.patch
> From 06ec0cacb9e59c009e61b920c7ac645f5c9fda46 Mon Sep 17 00:00:00 2001
> From: wm4 <nfxjfg at googlemail.com>
> Date: Sun, 29 Sep 2013 19:52:37 +0200
> Subject: [PATCH 1/2] swscale: make bilinear scaling the default
>
> Before this commit, sws_init_context() failed with an error if no scaler
> was explicitly set.
>
> Defaulting to something reasonable is better behavior.
> ---
> libswscale/options.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libswscale/options.c b/libswscale/options.c
> index 8985e6b..2b3147b 100644
> --- a/libswscale/options.c
> +++ b/libswscale/options.c
> @@ -34,7 +34,7 @@ static const char *sws_context_to_name(void *ptr)
> #define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
>
> static const AVOption swscale_options[] = {
> - { "sws_flags", "scaler flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, { .i64 = DEFAULT }, 0, UINT_MAX, VE, "sws_flags" },
> + { "sws_flags", "scaler flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, { .i64 = SWS_BILINEAR }, 0, UINT_MAX, VE, "sws_flags" },
> { "fast_bilinear", "fast bilinear", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_FAST_BILINEAR }, INT_MIN, INT_MAX, VE, "sws_flags" },
> { "bilinear", "bilinear", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_BILINEAR }, INT_MIN, INT_MAX, VE, "sws_flags" },
> { "bicubic", "bicubic", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_BICUBIC }, INT_MIN, INT_MAX, VE, "sws_flags" },
> --
applied
[...]
> @@ -2074,3 +2122,134 @@ struct SwsContext *sws_getCachedContext(struct SwsContext *context, int srcW,
> }
> return context;
> }
> +
> +int sws_set_src_filter(struct SwsContext *sws_context, SwsFilter *srcFilter)
> +{
> + SwsFilter *new_filter = sws_cloneFilter(srcFilter);
> + if (srcFilter && !new_filter)
> + return ENOMEM;
AVERROR(ENOMEM)
> +
> + sws_freeFilter(sws_context->user_src_filter);
> + sws_context->user_src_filter = new_filter;
> +
> + sws_flush_cache(sws_context);
> + return 0;
> +}
> +
> +int sws_set_dst_filter(struct SwsContext *sws_context, SwsFilter *dstFilter)
> +{
> + SwsFilter *new_filter = sws_cloneFilter(dstFilter);
> + if (dstFilter && !new_filter)
> + return ENOMEM;
AVERROR(ENOMEM)
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
If you think the mosad wants you dead since a long time then you are either
wrong or dead since a long time.
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