Function avifImageRGBToYUV

src/reformat.c:221–571

}

avifResult avifImageRGBToYUV(avifImage * image, const avifRGBImage * rgb)
{
    if (!rgb->pixels || rgb->format == AVIF_RGB_FORMAT_RGB_565) {
        return AVIF_RESULT_REFORMAT_FAILED;
    }

    avifReformatState state;
    if (!avifPrepareReformatState(image, rgb, &state)) {
        return AVIF_RESULT_REFORMAT_FAILED;
    }

    if (rgb->isFloat) {
        return AVIF_RESULT_NOT_IMPLEMENTED;
    }

    const avifBool hasAlpha = avifRGBFormatHasAlpha(rgb->format) && !rgb->ignoreAlpha;
    avifResult allocationResult = avifImageAllocatePlanes(image, hasAlpha ? AVIF_PLANES_ALL : AVIF_PLANES_YUV);
    if (allocationResult != AVIF_RESULT_OK) {
        return allocationResult;
    }

    avifAlphaMultiplyMode alphaMode = AVIF_ALPHA_MULTIPLY_MODE_NO_OP;
    if (hasAlpha) {
        if (!rgb->alphaPremultiplied && image->alphaPremultiplied) {
            alphaMode = AVIF_ALPHA_MULTIPLY_MODE_MULTIPLY;
        } else if (rgb->alphaPremultiplied && !image->alphaPremultiplied) {
            alphaMode = AVIF_ALPHA_MULTIPLY_MODE_UNMULTIPLY;
        }
    }

    const avifBool isGray = avifRGBFormatIsGray(rgb->format);
    avifBool converted = AVIF_FALSE;

    // Try converting with libsharpyuv.
    if (!isGray) {
        if ((rgb->chromaDownsampling == AVIF_CHROMA_DOWNSAMPLING_SHARP_YUV) && (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV420)) {
            const avifResult libSharpYUVResult = avifImageRGBToYUVLibSharpYUV(image, rgb, &state);
            if (libSharpYUVResult != AVIF_RESULT_OK) {
                // Return the error if sharpyuv was requested but failed for any reason, including libsharpyuv not being available.
                return libSharpYUVResult;
            }
            converted = AVIF_TRUE;
        }

        if (!converted && !rgb->avoidLibYUV && (alphaMode == AVIF_ALPHA_MULTIPLY_MODE_NO_OP)) {
            avifResult libyuvResult = avifImageRGBToYUVLibYUV(image, rgb);
            if (libyuvResult == AVIF_RESULT_OK) {
                converted = AVIF_TRUE;
            } else if (libyuvResult != AVIF_RESULT_NOT_IMPLEMENTED) {
                return libyuvResult;
            }
        }
    }

    if (!converted && !isGray) {
        const float kr = state.yuv.kr;
        const float kg = state.yuv.kg;
        const float kb = state.yuv.kb;