On 4/2/2021 11:40 AM, Anton Khirnov wrote:
Saves an allocation+free and two frame copies per each frame.
---
libavcodec/pngdec.c | 51 +++++++++++++++++++++++++--------------------
1 file changed, 28 insertions(+), 23 deletions(-)
diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 63c22063d9..095e4e86c2 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -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];
Is calling av_frame_make_writable(s->last_picture.f) valid at all?
Shouldn't the frame's buffer be freed with ff_thread_release_buffer()?
Especially if a non threading safe get_buffer2() callback was used.
Considering you can't call ff_thread_get_buffer() at this point to get a
new writable buffer to av_frame_copy() to, since this is long after
ff_thread_finish_setup() was called, not sure what else could be done.
+
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) {
- 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
+ if (s->blend_op == APNG_BLEND_OP_OVER) {
+ // Perform blending
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;
}
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