[FFmpeg-devel] [PATCH 2/2] avcodec/pngdec: add support for 'over' blend operation for 'none' dispose operation.
Benoit Fouet
benoit.fouet at free.fr
Thu Nov 27 15:26:27 CET 2014
---
libavcodec/pngdec.c | 160 +++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 133 insertions(+), 27 deletions(-)
diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 8529956..4c9d321 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -29,6 +29,7 @@
#include "png.h"
#include "pngdsp.h"
#include "thread.h"
+#include "libavformat/apng.h"
#include <zlib.h>
@@ -42,6 +43,9 @@ typedef struct PNGDecContext {
int state;
int width, height;
+ int cur_w, cur_h;
+ int x_offset, y_offset;
+ uint8_t dispose_op, blend_op;
int bit_depth;
int color_type;
int compression_type;
@@ -300,7 +304,7 @@ static void png_handle_row(PNGDecContext *s)
int got_line;
if (!s->interlace_type) {
- ptr = s->image_buf + s->image_linesize * s->y;
+ ptr = s->image_buf + s->image_linesize * (s->y + s->y_offset) + s->x_offset * s->bpp;
if (s->y == 0)
last_row = s->last_row;
else
@@ -319,7 +323,7 @@ static void png_handle_row(PNGDecContext *s)
}
}
s->y++;
- if (s->y == s->height) {
+ if (s->y == s->cur_h) {
s->state |= PNG_ALLIMAGE;
if (s->filter_type == PNG_FILTER_TYPE_LOCO) {
if (s->bit_depth == 16) {
@@ -334,7 +338,7 @@ static void png_handle_row(PNGDecContext *s)
} else {
got_line = 0;
for (;;) {
- ptr = s->image_buf + s->image_linesize * s->y;
+ ptr = s->image_buf + s->image_linesize * (s->y + s->y_offset) + s->x_offset * s->bpp;
if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
/* if we already read one row, it is time to stop to
* wait for the next one */
@@ -347,11 +351,11 @@ static void png_handle_row(PNGDecContext *s)
got_line = 1;
}
if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
- png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
+ png_put_interlaced_row(ptr, s->cur_w, s->bits_per_pixel, s->pass,
s->color_type, s->last_row);
}
s->y++;
- if (s->y == s->height) {
+ if (s->y == s->cur_h) {
memset(s->last_row, 0, s->row_size);
for (;;) {
if (s->pass == NB_PASSES - 1) {
@@ -362,7 +366,7 @@ static void png_handle_row(PNGDecContext *s)
s->y = 0;
s->pass_row_size = ff_png_pass_row_size(s->pass,
s->bits_per_pixel,
- s->width);
+ s->cur_w);
s->crow_size = s->pass_row_size + 1;
if (s->pass_row_size != 0)
break;
@@ -532,8 +536,8 @@ static int decode_ihdr_chunk(AVCodecContext *avctx, PNGDecContext *s,
return AVERROR_INVALIDDATA;
}
- s->width = bytestream2_get_be32(&s->gb);
- s->height = bytestream2_get_be32(&s->gb);
+ s->width = s->cur_w = bytestream2_get_be32(&s->gb);
+ s->height = s->cur_h = bytestream2_get_be32(&s->gb);
if (av_image_check_size(s->width, s->height, 0, avctx)) {
s->width = s->height = 0;
av_log(avctx, AV_LOG_ERROR, "Invalid image size\n");
@@ -588,7 +592,7 @@ static int decode_idat_chunk(AVCodecContext *avctx, PNGDecContext *s,
s->channels = ff_png_get_nb_channels(s->color_type);
s->bits_per_pixel = s->bit_depth * s->channels;
s->bpp = (s->bits_per_pixel + 7) >> 3;
- s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
+ s->row_size = (s->cur_w * s->bits_per_pixel + 7) >> 3;
if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
s->color_type == PNG_COLOR_TYPE_RGB) {
@@ -641,7 +645,7 @@ static int decode_idat_chunk(AVCodecContext *avctx, PNGDecContext *s,
s->pass = 0;
s->pass_row_size = ff_png_pass_row_size(s->pass,
s->bits_per_pixel,
- s->width);
+ s->cur_w);
s->crow_size = s->pass_row_size + 1;
}
av_dlog(avctx, "row_size=%d crow_size =%d\n",
@@ -670,6 +674,10 @@ static int decode_idat_chunk(AVCodecContext *avctx, PNGDecContext *s,
s->crow_buf = s->buffer + 15;
s->zstream.avail_out = s->crow_size;
s->zstream.next_out = s->crow_buf;
+
+ if (avctx->codec_id == AV_CODEC_ID_APNG &&
+ s->dispose_op == APNG_DISPOSE_OP_BACKGROUND)
+ memset(s->zstream.next_out, 0, s->zstream.avail_out);
}
s->state |= PNG_IDAT;
if ((ret = png_decode_idat(s, length)) < 0)
@@ -797,29 +805,39 @@ static void handle_small_bpp(PNGDecContext *s, AVFrame *p)
static int decode_fctl_chunk(AVCodecContext *avctx, PNGDecContext *s,
uint32_t length)
{
- uint32_t sequence_number, width, height, x_offset, y_offset;
+ uint32_t sequence_number;
if (length != 26)
return AVERROR_INVALIDDATA;
sequence_number = bytestream2_get_be32(&s->gb);
- width = bytestream2_get_be32(&s->gb);
- height = bytestream2_get_be32(&s->gb);
- x_offset = bytestream2_get_be32(&s->gb);
- y_offset = bytestream2_get_be32(&s->gb);
- bytestream2_skip(&s->gb, 10); /* delay_num (2)
- * delay_den (2)
- * dispose_op (1)
- * blend_op (1)
- * crc (4)
- */
-
- if (width != s->width || height != s->height ||
- x_offset != 0 || y_offset != 0) {
- if (sequence_number == 0)
+ s->cur_w = bytestream2_get_be32(&s->gb);
+ s->cur_h = bytestream2_get_be32(&s->gb);
+ s->x_offset = bytestream2_get_be32(&s->gb);
+ s->y_offset = bytestream2_get_be32(&s->gb);
+ bytestream2_skip(&s->gb, 4); /* delay_num (2), delay_den (2) */
+ s->dispose_op = bytestream2_get_byte(&s->gb);
+ s->blend_op = bytestream2_get_byte(&s->gb);
+ bytestream2_skip(&s->gb, 4); /* crc */
+
+ if (sequence_number == 0 &&
+ (s->cur_w != s->width ||
+ s->cur_h != s->height ||
+ s->x_offset != 0 ||
+ s->y_offset != 0) ||
+ s->cur_w <= 0 || s->cur_h <= 0 ||
+ s->x_offset < 0 || s->y_offset < 0 ||
+ s->cur_w > s->width - s->x_offset|| s->cur_h > s->height - s->y_offset)
return AVERROR_INVALIDDATA;
- avpriv_request_sample(avctx, "non key frames");
- return AVERROR_PATCHWELCOME;
+
+ /* always (re)start with a clean frame */
+ if (sequence_number == 0)
+ s->dispose_op = APNG_DISPOSE_OP_BACKGROUND;
+
+ if (s->dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
+ av_log(avctx, AV_LOG_ERROR,
+ "Dispose operation 'previous' is not yet implemented, using 'none'.\n");
+ s->dispose_op = APNG_DISPOSE_OP_NONE;
}
return 0;
@@ -841,6 +859,89 @@ static void handle_p_frame_png(PNGDecContext *s, AVFrame *p)
}
}
+// divide by 255 and round to nearest
+// apply a fast variant: (X+127)/255 = ((X+127)*257+257)>>16 = ((X+128)*257)>>16
+#define FAST_DIV255(x) ((((x) + 128) * 257) >> 16)
+
+static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
+ AVFrame *p)
+{
+ int i, j;
+ uint8_t *pd = p->data[0];
+ /* TODO make pd_last point to the one before for APNG_DISPOSE_OP_PREVIOUS */
+ uint8_t *pd_last = s->last_picture.f->data[0];
+ int ls = FFMIN(av_image_get_linesize(p->format, s->width, 0), s->width * s->bpp);
+
+ if (s->blend_op == APNG_BLEND_OP_OVER &&
+ avctx->pix_fmt != AV_PIX_FMT_RGBA && avctx->pix_fmt != AV_PIX_FMT_ARGB) {
+ avpriv_request_sample(avctx, "Blending with pixel format %s",
+ av_get_pix_fmt_name(avctx->pix_fmt));
+ return AVERROR_PATCHWELCOME;
+ }
+
+ ff_thread_await_progress(&s->last_picture, INT_MAX, 0);
+ for (j = 0; j < s->y_offset; j++) {
+ for (i = 0; i < ls; i++)
+ pd[i] = pd_last[i];
+ pd += s->image_linesize;
+ pd_last += s->image_linesize;
+ }
+
+ if (s->blend_op == APNG_BLEND_OP_OVER) {
+ uint8_t ri, gi, bi, ai;
+
+ if (avctx->pix_fmt == AV_PIX_FMT_RGBA) {
+ ri = 0;
+ gi = 1;
+ bi = 2;
+ ai = 3;
+ } else {
+ ri = 3;
+ gi = 2;
+ bi = 1;
+ ai = 0;
+ }
+
+ for (j = s->y_offset; j < s->y_offset + s->cur_h; j++) {
+ for (i = 0; i < s->x_offset * s->bpp; i++)
+ pd[i] = pd_last[i];
+ for (; i < (s->x_offset + s->cur_w) * s->bpp; i += s->bpp) {
+ uint8_t alpha = pd[i+ai];
+
+ /* output = alpha * foreground + (1-alpha) * background */
+ switch (alpha) {
+ case 0:
+ pd[i+ri] = pd_last[i+ri];
+ pd[i+gi] = pd_last[i+gi];
+ pd[i+bi] = pd_last[i+bi];
+ pd[i+ai] = 0xff;
+ break;
+ case 255:
+ break;
+ default:
+ pd[i+ri] = FAST_DIV255(alpha * pd[i+ri] + (255 - alpha) * pd_last[i+ri]);
+ pd[i+gi] = FAST_DIV255(alpha * pd[i+gi] + (255 - alpha) * pd_last[i+gi]);
+ pd[i+bi] = FAST_DIV255(alpha * pd[i+bi] + (255 - alpha) * pd_last[i+bi]);
+ pd[i+ai] = 0xff;
+ break;
+ }
+ }
+ for (; i < ls; i++)
+ pd[i] = pd_last[i];
+ pd += s->image_linesize;
+ pd_last += s->image_linesize;
+ }
+ }
+ for (j = s->y_offset + s->cur_h; j < s->height; j++) {
+ for (i = 0; i < ls; i++)
+ pd[i] = pd_last[i];
+ pd += s->image_linesize;
+ pd_last += s->image_linesize;
+ }
+
+ return 0;
+}
+
static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
AVFrame *p, AVPacket *avpkt)
{
@@ -952,7 +1053,12 @@ exit_loop:
&& s->last_picture.f->height== p->height
&& s->last_picture.f->format== p->format
) {
+ if (CONFIG_PNG_DECODER && avctx->codec_id != AV_CODEC_ID_APNG)
handle_p_frame_png(s, p);
+ else if (CONFIG_APNG_DECODER &&
+ avctx->codec_id == AV_CODEC_ID_APNG &&
+ (ret = handle_p_frame_apng(avctx, s, p)) < 0)
+ goto fail;
}
}
ff_thread_report_progress(&s->picture, INT_MAX, 0);
--
2.2.0.rc2.23.gca0107e
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