[FFmpeg-devel] [PATCH] swscale/unscaled: add pal8 -> gbr(a)p special converter

[James Almer]

On 12/18/2024 11:24 AM, Niklas Haas wrote:
> From: Niklas Haas <git at haasn.dev>
> 
> Fixes: ticket #9520
> Signed-off-by: Niklas Haas <git at haasn.dev>
> Sponsored-by: Sovereign Tech Fund
> ---
>   libswscale/swscale.c          |  2 +
>   libswscale/swscale_unscaled.c | 81 ++++++++++++++++++++++++++++++++++-
>   2 files changed, 81 insertions(+), 2 deletions(-)
> 
> diff --git a/libswscale/swscale.c b/libswscale/swscale.c
> index 96634acfd6..bd5b6370db 100644
> --- a/libswscale/swscale.c
> +++ b/libswscale/swscale.c
> @@ -910,6 +910,8 @@ void ff_update_palette(SwsInternal *c, const uint32_t *pal)
>           case AV_PIX_FMT_BGR32_1:
>   #if HAVE_BIGENDIAN
>           case AV_PIX_FMT_BGR24:
> +        case AV_PIX_FMT_BGRP:
> +        case AV_PIX_FMT_BGRAP:

These don't exist. And GBRP/GBRAP would need c->pal_rgb to be ordered in 
a different way.

>   #endif
>               c->pal_rgb[i]= a + (r<<8) + (g<<16) + ((unsigned)b<<24);
>               break;
> diff --git a/libswscale/swscale_unscaled.c b/libswscale/swscale_unscaled.c
> index c7ad6b014a..973ffe0299 100644
> --- a/libswscale/swscale_unscaled.c
> +++ b/libswscale/swscale_unscaled.c
> @@ -509,6 +509,34 @@ static void gray8aToPacked24(const uint8_t *src, uint8_t *dst, int num_pixels,
>       }
>   }
>   
> +static void gray8aToPlanar8(const uint8_t *src, uint8_t *dstG, uint8_t *dstB,
> +                            uint8_t *dstR, uint8_t *dstA, int num_pixels,
> +                            const uint8_t *palette)
> +{
> +    for (int i = 0; i < num_pixels; i++) {
> +        const uint8_t *rgb = &palette[src[i << 1] * 4];
> +        dstB[i] = rgb[0];
> +        dstG[i] = rgb[1];
> +        dstR[i] = rgb[2];
> +        if (dstA)
> +            dstA[i] = src[(i << 1) + 1];
> +    }
> +}
> +
> +static void pal8ToPlanar8(const uint8_t *src, uint8_t *dstG, uint8_t *dstB,
> +                          uint8_t *dstR, uint8_t *dstA, int num_pixels,
> +                          const uint8_t *palette)
> +{
> +    for (int i = 0; i < num_pixels; i++) {
> +        const uint8_t *rgba = &palette[src[i] * 4];

Does this work in both big and little endian? c->pal_rgb is uint32_t, 
and ff_update_palette() sets it in a native endian way.

> +        dstB[i] = rgba[0];
> +        dstG[i] = rgba[1];
> +        dstR[i] = rgba[2];
> +        if (dstA)
> +            dstA[i] = rgba[3];
> +    }
> +}
> +
>   static int bswap_16bpc(SwsInternal *c, const uint8_t *const src[],
>                                 const int srcStride[], int srcSliceY, int srcSliceH,
>                                 uint8_t *const dst[], const int dstStride[])
> @@ -610,6 +638,45 @@ static int palToRgbWrapper(SwsInternal *c, const uint8_t *const src[], const int
>       return srcSliceH;
>   }
>   
> +static int palToGbrpWrapper(SwsInternal *c, const uint8_t *const src[],
> +                            const int srcStride[], int srcSliceY, int srcSliceH,
> +                            uint8_t *const dst[], const int dstStride[])
> +{
> +    const enum AVPixelFormat srcFormat = c->opts.src_format;
> +    const enum AVPixelFormat dstFormat = c->opts.dst_format;
> +    void (*conv)(const uint8_t *src, uint8_t *dstG, uint8_t *dstB, uint8_t *dstR,
> +                 uint8_t *dstA, int num_pixels, const uint8_t *palette) = NULL;
> +
> +    const int num_planes = isALPHA(dstFormat) ? 4 : 3;
> +    const uint8_t *srcPtr = src[0];
> +    uint8_t *dstPtr[4] = {0};
> +    for (int i = 0; i < num_planes; i++)
> +        dstPtr[i] = dst[i] + dstStride[i] * srcSliceY;
> +
> +    if (srcFormat == AV_PIX_FMT_YA8) {
> +        switch (dstFormat) {
> +        case AV_PIX_FMT_GBRP:  conv = gray8aToPlanar8; break;
> +        case AV_PIX_FMT_GBRAP: conv = gray8aToPlanar8; break;
> +        }
> +    } else if (usePal(srcFormat)) {
> +        switch (dstFormat) {
> +        case AV_PIX_FMT_GBRP:  conv = pal8ToPlanar8; break;
> +        case AV_PIX_FMT_GBRAP: conv = pal8ToPlanar8; break;
> +        }
> +    }
> +
> +    av_assert1(conv);
> +    for (int y = 0; y < srcSliceH; y++) {
> +        conv(srcPtr, dstPtr[0], dstPtr[1], dstPtr[2], dstPtr[3], c->opts.src_w,
> +            (uint8_t *) c->pal_rgb);
> +        srcPtr += srcStride[0];
> +        for (int i = 0; i < num_planes; i++)
> +            dstPtr[i] += dstStride[i];
> +    }
> +
> +    return srcSliceH;
> +}
> +
>   static void packed16togbra16(const uint8_t *src, int srcStride,
>                                uint16_t *dst[], const int dstStride[], int srcSliceH,
>                                int src_alpha, int swap, int shift, int width)
> @@ -2529,8 +2596,18 @@ void ff_get_unscaled_swscale(SwsInternal *c)
>           IS_DIFFERENT_ENDIANESS(srcFormat, dstFormat, AV_PIX_FMT_GBRAPF32))
>           c->convert_unscaled = bswap_32bpc;
>   
> -    if (usePal(srcFormat) && isByteRGB(dstFormat))
> -        c->convert_unscaled = palToRgbWrapper;
> +    if (usePal(srcFormat)) {
> +        switch (dstFormat) {
> +        case AV_PIX_FMT_GBRP:
> +        case AV_PIX_FMT_GBRAP:
> +            c->convert_unscaled = palToGbrpWrapper;
> +            break;
> +        default:
> +            if (isByteRGB(dstFormat))
> +                c->convert_unscaled = palToRgbWrapper;
> +            break;
> +        }
> +    }
>   
>       if (srcFormat == AV_PIX_FMT_YUV422P) {
>           if (dstFormat == AV_PIX_FMT_YUYV422)

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