[FFmpeg-devel] [PATCH v7 04/12] swscale: expose SwsContext publicly

[Michael Niedermayer]

Hi Niklas

On Sat, Nov 16, 2024 at 12:24:59PM +0100, Niklas Haas wrote:
> From: Niklas Haas <git at haasn.dev>
> 
> Following in the footsteps of the work in the previous commit, it's now
> relatively straightforward to expose the options struct publicly as
> SwsContext. This is a step towards making this more user friendly, as
> well as following API conventions established elsewhere.
> 
> Sponsored-by: Sovereign Tech Fund
> Signed-off-by: Niklas Haas <git at haasn.dev>
> ---
>  libswscale/swscale.h          |  93 +++++++++++++++++++++++--
>  libswscale/swscale_internal.h |  45 +------------
>  libswscale/utils.c            | 123 +++++++++++++++-------------------
>  3 files changed, 144 insertions(+), 117 deletions(-)
> 
> diff --git a/libswscale/swscale.h b/libswscale/swscale.h
> index 50c705ae06..4baef532b6 100644
> --- a/libswscale/swscale.h
> +++ b/libswscale/swscale.h
> @@ -42,8 +42,6 @@
>  #include "version.h"
>  #endif
>  
> -typedef struct SwsContext SwsContext;
> -
>  /**
>   * @defgroup libsws libswscale
>   * Color conversion and scaling library.
> @@ -65,17 +63,98 @@ const char *swscale_configuration(void);
>  const char *swscale_license(void);
>  
>  /**
> - * Get the AVClass for swsContext. It can be used in combination with
> + * Get the AVClass for SwsContext. It can be used in combination with
>   * AV_OPT_SEARCH_FAKE_OBJ for examining options.
>   *
>   * @see av_opt_find().
>   */
>  const AVClass *sws_get_class(void);
>  
> -/**
> - * Allocate an empty SwsContext. This must be filled and passed to
> - * sws_init_context(). For filling see AVOptions, options.c and
> - * sws_setColorspaceDetails().
> +/******************************
> + * Flags and quality settings *
> + ******************************/
> +
> +typedef enum SwsDither {
> +    SWS_DITHER_NONE = 0, /* disable dithering */
> +    SWS_DITHER_AUTO,     /* auto-select from preset */
> +    SWS_DITHER_BAYER,    /* ordered dither matrix */
> +    SWS_DITHER_ED,       /* error diffusion */
> +    SWS_DITHER_A_DITHER, /* arithmetic addition */
> +    SWS_DITHER_X_DITHER, /* arithmetic xor */
> +    SWS_DITHER_NB,       /* not part of the ABI */
> +} SwsDither;
> +
> +typedef enum SwsAlphaBlend {
> +    SWS_ALPHA_BLEND_NONE = 0,
> +    SWS_ALPHA_BLEND_UNIFORM,
> +    SWS_ALPHA_BLEND_CHECKERBOARD,
> +    SWS_ALPHA_BLEND_NB,  /* not part of the ABI */
> +} SwsAlphaBlend;
> +
> +/***********************************
> + * Context creation and management *
> + ***********************************/
> +
> +/**
> + * Main external API structure. New fields can be added to the end with
> + * minor version bumps. Removal, reordering and changes to existing fields
> + * require a major version bump. sizeof(SwsContext) is not part of the ABI.
> + */
> +typedef struct SwsContext {
> +    const AVClass *av_class;
> +
> +    /**
> +     * Private data of the user, can be used to carry app specific stuff.
> +     */
> +    void *opaque;
> +

> +    /**
> +     * Bitmask of SWS_*.
> +     */
> +    unsigned flags;

uint64_t seems more future proof


> +
> +    /**
> +     * Extra parameters for fine-tuning certain scalers.
> +     */
> +    double scaler_params[2];
> +
> +    /**
> +     * How many threads to use for processing, or 0 for automatic selection.
> +     */
> +    int threads;
> +

> +    /**
> +     * Dither mode.
> +     */
> +    SwsDither dither;
> +
> +    /**
> +     * Alpha blending mode. See `SwsAlphaBlend` for details.
> +     */
> +    SwsAlphaBlend alpha_blend;

Is this intended to be used with AVOptions ?
enums as type can be problematic IIRC

patch should be ok otherwise

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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