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lavc/pngdec: perform APNG blending in-place

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Saves an allocation+free and two frame copies per each frame.

(cherry picked from commit 5a50bd88db)
Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Anton Khirnov 2021-04-01 15:45:45 +02:00
parent 5c457c673f
commit 53ecdbfbe5
1 changed files with 28 additions and 23 deletions
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51
libavcodec/pngdec.c
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@ -1068,8 +1068,12 @@ static void handle_p_frame_png(PNGDecContext *s, AVFrame *p)
static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
AVFrame *p)
{
uint8_t *dst = p->data[0];
ptrdiff_t dst_stride = p->linesize[0];
const uint8_t *src = s->last_picture.f->data[0];
ptrdiff_t src_stride = s->last_picture.f->linesize[0];
size_t x, y;
uint8_t *buffer;
if (s->blend_op == APNG_BLEND_OP_OVER &&
avctx->pix_fmt != AV_PIX_FMT_RGBA &&
@ -1089,26 +1093,32 @@ static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
if (ret < 0)
return ret;
src = s->last_picture.f->data[0];
src_stride = s->last_picture.f->linesize[0];
for (y = s->last_y_offset; y < s->last_y_offset + s->last_h; y++) {
memset(s->last_picture.f->data[0] + s->image_linesize * y +
memset(s->last_picture.f->data[0] + src_stride * y +
s->bpp * s->last_x_offset, 0, s->bpp * s->last_w);
}
}
buffer = av_memdup(s->last_picture.f->data[0], s->image_linesize * s->height);
if (!buffer)
return AVERROR(ENOMEM);
// copy unchanged rectangles from the last frame
for (y = 0; y < s->y_offset; y++)
memcpy(dst + y * dst_stride, src + y * src_stride, p->width * s->bpp);
for (y = s->y_offset; y < s->y_offset + s->cur_h; y++) {
memcpy(dst + y * dst_stride, src + y * src_stride, s->x_offset * s->bpp);
memcpy(dst + y * dst_stride + (s->x_offset + s->cur_w) * s->bpp,
src + y * src_stride + (s->x_offset + s->cur_w) * s->bpp,
(p->width - s->cur_w - s->x_offset) * s->bpp);
}
for (y = s->y_offset + s->cur_h; y < p->height; y++)
memcpy(dst + y * dst_stride, src + y * src_stride, p->width * s->bpp);
// Perform blending
if (s->blend_op == APNG_BLEND_OP_SOURCE) {
if (s->blend_op == APNG_BLEND_OP_OVER) {
// Perform blending
for (y = s->y_offset; y < s->y_offset + s->cur_h; ++y) {
size_t row_start = s->image_linesize * y + s->bpp * s->x_offset;
memcpy(buffer + row_start, p->data[0] + row_start, s->bpp * s->cur_w);
}
} else { // APNG_BLEND_OP_OVER
for (y = s->y_offset; y < s->y_offset + s->cur_h; ++y) {
uint8_t *foreground = p->data[0] + s->image_linesize * y + s->bpp * s->x_offset;
uint8_t *background = buffer + s->image_linesize * y + s->bpp * s->x_offset;
uint8_t *foreground = dst + dst_stride * y + s->bpp * s->x_offset;
const uint8_t *background = src + src_stride * y + s->bpp * s->x_offset;
for (x = s->x_offset; x < s->x_offset + s->cur_w; ++x, foreground += s->bpp, background += s->bpp) {
size_t b;
uint8_t foreground_alpha, background_alpha, output_alpha;
@ -1135,18 +1145,17 @@ static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
break;
}
if (foreground_alpha == 0)
if (foreground_alpha == 255)
continue;
if (foreground_alpha == 255) {
memcpy(background, foreground, s->bpp);
if (foreground_alpha == 0) {
memcpy(foreground, background, s->bpp);
continue;
}
if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
// TODO: Alpha blending with PAL8 will likely need the entire image converted over to RGBA first
avpriv_request_sample(avctx, "Alpha blending palette samples");
background[0] = foreground[0];
continue;
}
@ -1164,15 +1173,11 @@ static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
}
}
output[b] = output_alpha;
memcpy(background, output, s->bpp);
memcpy(foreground, output, s->bpp);
}
}
}
// Copy blended buffer into the frame and free
memcpy(p->data[0], buffer, s->image_linesize * s->height);
av_free(buffer);
return 0;
}