[FFmpeg-devel] [PATCH] avfilter/vf_overlay: add premultiplied alpha mode

Paul B Mahol onemda at gmail.com
Sat Dec 2 12:00:31 EET 2017


On 12/2/17, Marton Balint <cus at passwd.hu> wrote:
>
>
> On Fri, 1 Dec 2017, Paul B Mahol wrote:
>
>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>> ---
>> doc/filters.texi         |   4 ++
>> libavfilter/vf_overlay.c | 160
>> ++++++++++++++++++++++++++++++++++++++++-------
>> 2 files changed, 140 insertions(+), 24 deletions(-)
>>
>> diff --git a/doc/filters.texi b/doc/filters.texi
>> index f7c371592f..0699728b7e 100644
>> --- a/doc/filters.texi
>> +++ b/doc/filters.texi
>> @@ -11328,6 +11328,10 @@ Default value is @samp{yuv420}.
>>
>> @item repeatlast
>> See @ref{framesync}.
>> +
>> + at item alpha
>> +Set format of alpha, it can be @var{straight} or @var{premultiplied}.
>> +Default is @var{straight}.
>> @end table
>
> Does this mean that not only overlay, but input and output is also
> considered as premultiplied? Maybe better to clarify this in the docs.

I done it for overlay only alpha. For rest I'm little confused what needs doing.

>
> Have you measured the slowdown caused by the extra condition in the pixel
> blending code? If it is more than 1-2%, then some DEFINE magic (or
> making the blend_image functions inline?) would be better IMHO.

It should already be inlined. Thats why there are so many functions.

>
> Regards,
> Marton
>
>>
>> The @option{x}, and @option{y} expressions can contain the following
>> diff --git a/libavfilter/vf_overlay.c b/libavfilter/vf_overlay.c
>> index 5bf3d66cf1..8206dae454 100644
>> --- a/libavfilter/vf_overlay.c
>> +++ b/libavfilter/vf_overlay.c
>> @@ -109,6 +109,7 @@ typedef struct OverlayContext {
>>     uint8_t overlay_rgba_map[4];
>>     uint8_t overlay_has_alpha;
>>     int format;                 ///< OverlayFormat
>> +    int alpha_format;
>>     int eval_mode;              ///< EvalMode
>>
>>     FFFrameSync fs;
>> @@ -403,7 +404,8 @@ static int config_output(AVFilterLink *outlink)
>>
>> static void blend_image_packed_rgb(AVFilterContext *ctx,
>>                                    AVFrame *dst, const AVFrame *src,
>> -                                   int main_has_alpha, int x, int y)
>> +                                   int main_has_alpha, int x, int y,
>> +                                   int is_straight)
>> {
>>     OverlayContext *s = ctx->priv;
>>     int i, imax, j, jmax;
>> @@ -454,9 +456,9 @@ static void blend_image_packed_rgb(AVFilterContext
>> *ctx,
>>             default:
>>                 // main_value = main_value * (1 - alpha) + overlay_value *
>> alpha
>>                 // since alpha is in the range 0-255, the result must
>> divided by 255
>> -                d[dr] = FAST_DIV255(d[dr] * (255 - alpha) + S[sr] *
>> alpha);
>> -                d[dg] = FAST_DIV255(d[dg] * (255 - alpha) + S[sg] *
>> alpha);
>> -                d[db] = FAST_DIV255(d[db] * (255 - alpha) + S[sb] *
>> alpha);
>> +                d[dr] = is_straight ? FAST_DIV255(d[dr] * (255 - alpha) +
>> S[sr] * alpha) : FAST_DIV255(d[dr] * (255 - alpha) + S[sr]);
>> +                d[dg] = is_straight ? FAST_DIV255(d[dg] * (255 - alpha) +
>> S[sg] * alpha) : FAST_DIV255(d[dr] * (255 - alpha) + S[sr]);
>> +                d[db] = is_straight ? FAST_DIV255(d[db] * (255 - alpha) +
>> S[sb] * alpha) : FAST_DIV255(d[dr] * (255 - alpha) + S[sr]);
>>             }
>>             if (main_has_alpha) {
>>                 switch (alpha) {
>> @@ -487,7 +489,9 @@ static av_always_inline void
>> blend_plane(AVFilterContext *ctx,
>>                                          int main_has_alpha,
>>                                          int dst_plane,
>>                                          int dst_offset,
>> -                                         int dst_step)
>> +                                         int dst_step,
>> +                                         int straight,
>> +                                         int yuv)
>> {
>>     int src_wp = AV_CEIL_RSHIFT(src_w, hsub);
>>     int src_hp = AV_CEIL_RSHIFT(src_h, vsub);
>> @@ -546,7 +550,14 @@ static av_always_inline void
>> blend_plane(AVFilterContext *ctx,
>>                     alpha_d = da[0];
>>                 alpha = UNPREMULTIPLY_ALPHA(alpha, alpha_d);
>>             }
>> -            *d = FAST_DIV255(*d * (255 - alpha) + *s * alpha);
>> +            if (straight) {
>> +                *d = FAST_DIV255(*d * (255 - alpha) + *s * alpha);
>> +            } else {
>> +                if (i && yuv)
>> +                    *d = av_clip(FAST_DIV255((*d - 128) * (255 - alpha))
>> + *s - 128, -128, 128) + 128;
>> +                else
>> +                    *d = FFMIN(FAST_DIV255(*d * (255 - alpha)) + *s,
>> 255);
>> +            }
>>             s++;
>>             d += dst_step;
>>             da += 1 << hsub;
>> @@ -605,7 +616,8 @@ static av_always_inline void
>> blend_image_yuv(AVFilterContext *ctx,
>>                                              AVFrame *dst, const AVFrame
>> *src,
>>                                              int hsub, int vsub,
>>                                              int main_has_alpha,
>> -                                             int x, int y)
>> +                                             int x, int y,
>> +                                             int is_straight)
>> {
>>     OverlayContext *s = ctx->priv;
>>     const int src_w = src->width;
>> @@ -614,11 +626,11 @@ static av_always_inline void
>> blend_image_yuv(AVFilterContext *ctx,
>>     const int dst_h = dst->height;
>>
>>     blend_plane(ctx, dst, src, src_w, src_h, dst_w, dst_h, 0, 0,       0,
>> x, y, main_has_alpha,
>> -                s->main_desc->comp[0].plane,
>> s->main_desc->comp[0].offset, s->main_desc->comp[0].step);
>> +                s->main_desc->comp[0].plane,
>> s->main_desc->comp[0].offset, s->main_desc->comp[0].step, is_straight, 1);
>>     blend_plane(ctx, dst, src, src_w, src_h, dst_w, dst_h, 1, hsub, vsub,
>> x, y, main_has_alpha,
>> -                s->main_desc->comp[1].plane,
>> s->main_desc->comp[1].offset, s->main_desc->comp[1].step);
>> +                s->main_desc->comp[1].plane,
>> s->main_desc->comp[1].offset, s->main_desc->comp[1].step, is_straight, 1);
>>     blend_plane(ctx, dst, src, src_w, src_h, dst_w, dst_h, 2, hsub, vsub,
>> x, y, main_has_alpha,
>> -                s->main_desc->comp[2].plane,
>> s->main_desc->comp[2].offset, s->main_desc->comp[2].step);
>> +                s->main_desc->comp[2].plane,
>> s->main_desc->comp[2].offset, s->main_desc->comp[2].step, is_straight, 1);
>>
>>     if (main_has_alpha)
>>         alpha_composite(src, dst, src_w, src_h, dst_w, dst_h, x, y);
>> @@ -628,7 +640,8 @@ static av_always_inline void
>> blend_image_planar_rgb(AVFilterContext *ctx,
>>                                                     AVFrame *dst, const
>> AVFrame *src,
>>                                                     int hsub, int vsub,
>>                                                     int main_has_alpha,
>> -                                                    int x, int y)
>> +                                                    int x, int y,
>> +                                                    int is_straight)
>> {
>>     OverlayContext *s = ctx->priv;
>>     const int src_w = src->width;
>> @@ -637,11 +650,11 @@ static av_always_inline void
>> blend_image_planar_rgb(AVFilterContext *ctx,
>>     const int dst_h = dst->height;
>>
>>     blend_plane(ctx, dst, src, src_w, src_h, dst_w, dst_h, 0, 0,       0,
>> x, y, main_has_alpha,
>> -                s->main_desc->comp[1].plane,
>> s->main_desc->comp[1].offset, s->main_desc->comp[1].step);
>> +                s->main_desc->comp[1].plane,
>> s->main_desc->comp[1].offset, s->main_desc->comp[1].step, is_straight, 0);
>>     blend_plane(ctx, dst, src, src_w, src_h, dst_w, dst_h, 1, hsub, vsub,
>> x, y, main_has_alpha,
>> -                s->main_desc->comp[2].plane,
>> s->main_desc->comp[2].offset, s->main_desc->comp[2].step);
>> +                s->main_desc->comp[2].plane,
>> s->main_desc->comp[2].offset, s->main_desc->comp[2].step, is_straight, 0);
>>     blend_plane(ctx, dst, src, src_w, src_h, dst_w, dst_h, 2, hsub, vsub,
>> x, y, main_has_alpha,
>> -                s->main_desc->comp[0].plane,
>> s->main_desc->comp[0].offset, s->main_desc->comp[0].step);
>> +                s->main_desc->comp[0].plane,
>> s->main_desc->comp[0].offset, s->main_desc->comp[0].step, is_straight, 0);
>>
>>     if (main_has_alpha)
>>         alpha_composite(src, dst, src_w, src_h, dst_w, dst_h, x, y);
>> @@ -649,52 +662,102 @@ static av_always_inline void
>> blend_image_planar_rgb(AVFilterContext *ctx,
>>
>> static void blend_image_yuv420(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_yuv(ctx, dst, src, 1, 1, 0, x, y);
>> +    blend_image_yuv(ctx, dst, src, 1, 1, 0, x, y, 1);
>> }
>>
>> static void blend_image_yuva420(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_yuv(ctx, dst, src, 1, 1, 1, x, y);
>> +    blend_image_yuv(ctx, dst, src, 1, 1, 1, x, y, 1);
>> }
>>
>> static void blend_image_yuv422(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_yuv(ctx, dst, src, 1, 0, 0, x, y);
>> +    blend_image_yuv(ctx, dst, src, 1, 0, 0, x, y, 1);
>> }
>>
>> static void blend_image_yuva422(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_yuv(ctx, dst, src, 1, 0, 1, x, y);
>> +    blend_image_yuv(ctx, dst, src, 1, 0, 1, x, y, 1);
>> }
>>
>> static void blend_image_yuv444(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_yuv(ctx, dst, src, 0, 0, 0, x, y);
>> +    blend_image_yuv(ctx, dst, src, 0, 0, 0, x, y, 1);
>> }
>>
>> static void blend_image_yuva444(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_yuv(ctx, dst, src, 0, 0, 1, x, y);
>> +    blend_image_yuv(ctx, dst, src, 0, 0, 1, x, y, 1);
>> }
>>
>> static void blend_image_gbrp(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_planar_rgb(ctx, dst, src, 0, 0, 0, x, y);
>> +    blend_image_planar_rgb(ctx, dst, src, 0, 0, 0, x, y, 1);
>> }
>>
>> static void blend_image_gbrap(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_planar_rgb(ctx, dst, src, 0, 0, 1, x, y);
>> +    blend_image_planar_rgb(ctx, dst, src, 0, 0, 1, x, y, 1);
>> +}
>> +
>> +static void blend_image_yuv420_pm(AVFilterContext *ctx, AVFrame *dst,
>> const AVFrame *src, int x, int y)
>> +{
>> +    blend_image_yuv(ctx, dst, src, 1, 1, 0, x, y, 0);
>> +}
>> +
>> +static void blend_image_yuva420_pm(AVFilterContext *ctx, AVFrame *dst,
>> const AVFrame *src, int x, int y)
>> +{
>> +    blend_image_yuv(ctx, dst, src, 1, 1, 1, x, y, 0);
>> +}
>> +
>> +static void blend_image_yuv422_pm(AVFilterContext *ctx, AVFrame *dst,
>> const AVFrame *src, int x, int y)
>> +{
>> +    blend_image_yuv(ctx, dst, src, 1, 0, 0, x, y, 0);
>> +}
>> +
>> +static void blend_image_yuva422_pm(AVFilterContext *ctx, AVFrame *dst,
>> const AVFrame *src, int x, int y)
>> +{
>> +    blend_image_yuv(ctx, dst, src, 1, 0, 1, x, y, 0);
>> +}
>> +
>> +static void blend_image_yuv444_pm(AVFilterContext *ctx, AVFrame *dst,
>> const AVFrame *src, int x, int y)
>> +{
>> +    blend_image_yuv(ctx, dst, src, 0, 0, 0, x, y, 0);
>> +}
>> +
>> +static void blend_image_yuva444_pm(AVFilterContext *ctx, AVFrame *dst,
>> const AVFrame *src, int x, int y)
>> +{
>> +    blend_image_yuv(ctx, dst, src, 0, 0, 1, x, y, 0);
>> +}
>> +
>> +static void blend_image_gbrp_pm(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> +{
>> +    blend_image_planar_rgb(ctx, dst, src, 0, 0, 0, x, y, 0);
>> +}
>> +
>> +static void blend_image_gbrap_pm(AVFilterContext *ctx, AVFrame *dst,
>> const AVFrame *src, int x, int y)
>> +{
>> +    blend_image_planar_rgb(ctx, dst, src, 0, 0, 1, x, y, 0);
>> }
>>
>> static void blend_image_rgb(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_packed_rgb(ctx, dst, src, 0, x, y);
>> +    blend_image_packed_rgb(ctx, dst, src, 0, x, y, 0);
>> }
>>
>> static void blend_image_rgba(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> {
>> -    blend_image_packed_rgb(ctx, dst, src, 1, x, y);
>> +    blend_image_packed_rgb(ctx, dst, src, 1, x, y, 0);
>> +}
>> +
>> +static void blend_image_rgb_pm(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> +{
>> +    blend_image_packed_rgb(ctx, dst, src, 0, x, y, 1);
>> +}
>> +
>> +static void blend_image_rgba_pm(AVFilterContext *ctx, AVFrame *dst, const
>> AVFrame *src, int x, int y)
>> +{
>> +    blend_image_packed_rgb(ctx, dst, src, 1, x, y, 1);
>> }
>>
>> static int config_input_main(AVFilterLink *inlink)
>> @@ -754,6 +817,52 @@ static int config_input_main(AVFilterLink *inlink)
>>         }
>>         break;
>>     }
>> +
>> +    if (!s->alpha_format)
>> +        return 0;
>> +
>> +    switch (s->format) {
>> +    case OVERLAY_FORMAT_YUV420:
>> +        s->blend_image = s->main_has_alpha ? blend_image_yuva420_pm :
>> blend_image_yuv420_pm;
>> +        break;
>> +    case OVERLAY_FORMAT_YUV422:
>> +        s->blend_image = s->main_has_alpha ? blend_image_yuva422_pm :
>> blend_image_yuv422_pm;
>> +        break;
>> +    case OVERLAY_FORMAT_YUV444:
>> +        s->blend_image = s->main_has_alpha ? blend_image_yuva444_pm :
>> blend_image_yuv444_pm;
>> +        break;
>> +    case OVERLAY_FORMAT_RGB:
>> +        s->blend_image = s->main_has_alpha ? blend_image_rgba_pm :
>> blend_image_rgb_pm;
>> +        break;
>> +    case OVERLAY_FORMAT_GBRP:
>> +        s->blend_image = s->main_has_alpha ? blend_image_gbrap_pm :
>> blend_image_gbrp_pm;
>> +        break;
>> +    case OVERLAY_FORMAT_AUTO:
>> +        switch (inlink->format) {
>> +        case AV_PIX_FMT_YUVA420P:
>> +            s->blend_image = blend_image_yuva420_pm;
>> +            break;
>> +        case AV_PIX_FMT_YUVA422P:
>> +            s->blend_image = blend_image_yuva422_pm;
>> +            break;
>> +        case AV_PIX_FMT_YUVA444P:
>> +            s->blend_image = blend_image_yuva444_pm;
>> +            break;
>> +        case AV_PIX_FMT_ARGB:
>> +        case AV_PIX_FMT_RGBA:
>> +        case AV_PIX_FMT_BGRA:
>> +        case AV_PIX_FMT_ABGR:
>> +            s->blend_image = blend_image_rgba_pm;
>> +            break;
>> +        case AV_PIX_FMT_GBRAP:
>> +            s->blend_image = blend_image_gbrap_pm;
>> +            break;
>> +        default:
>> +            av_assert0(0);
>> +            break;
>> +        }
>> +        break;
>> +    }
>>     return 0;
>> }
>>
>> @@ -835,6 +944,9 @@ static const AVOption overlay_options[] = {
>>         { "gbrp",   "", 0, AV_OPT_TYPE_CONST, {.i64=OVERLAY_FORMAT_GBRP},
>>  .flags = FLAGS, .unit = "format" },
>>         { "auto",   "", 0, AV_OPT_TYPE_CONST, {.i64=OVERLAY_FORMAT_AUTO},
>>  .flags = FLAGS, .unit = "format" },
>>     { "repeatlast", "repeat overlay of the last overlay frame",
>> OFFSET(fs.opt_repeatlast), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, FLAGS },
>> +    { "alpha", "alpha format", OFFSET(alpha_format), AV_OPT_TYPE_INT,
>> {.i64=0}, 0, 1, FLAGS, "alpha_format" },
>> +        { "straight",      "", 0, AV_OPT_TYPE_CONST, {.i64=0}, .flags =
>> FLAGS, .unit = "alpha_format" },
>> +        { "premultiplied", "", 0, AV_OPT_TYPE_CONST, {.i64=1}, .flags =
>> FLAGS, .unit = "alpha_format" },
>>     { NULL }
>> };
>>
>> --
>> 2.11.0
>>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>


More information about the ffmpeg-devel mailing list