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Code Issues Releases Activity

avcodec/flashsvenc: Fix packet size calculation

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The earlier code did not account for the frame header as well
as the block headers; furthermore, in case a large part of
a block is unused (due to padding), the output size may
exceed 3 * width * height (where the dimensions correspond
to the visible pixels) due to the overhead of the zlib header,
so use the padded dimensions to calculate the maximum packet size
(which is also what the actual call to compress2() uses).
Fixes ticket #10053.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2022-11-19 02:12:02 +01:00
parent 715bf3509a
commit 6695983111
1 changed files with 12 additions and 1 deletions
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13
libavcodec/flashsvenc.c
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@ -54,11 +54,15 @@
#include "put_bits.h"
#include "bytestream.h"
/* These values are hardcoded for now. */
#define BLOCK_WIDTH (4 * 16U)
#define BLOCK_HEIGHT (4 * 16U)
typedef struct FlashSVContext {
AVCodecContext *avctx;
uint8_t *previous_frame;
int image_width, image_height;
unsigned packet_size;
int block_width, block_height;
uint8_t *encbuffer;
int block_size;
@ -100,6 +104,7 @@ static av_cold int flashsv_encode_end(AVCodecContext *avctx)
static av_cold int flashsv_encode_init(AVCodecContext *avctx)
{
FlashSVContext *s = avctx->priv_data;
int h_blocks, v_blocks, nb_blocks;
s->avctx = avctx;
@ -114,6 +119,11 @@ static av_cold int flashsv_encode_init(AVCodecContext *avctx)
s->image_width = avctx->width;
s->image_height = avctx->height;
h_blocks = (s->image_width + BLOCK_WIDTH - 1) / BLOCK_WIDTH;
v_blocks = (s->image_height + BLOCK_WIDTH - 1) / BLOCK_WIDTH;
nb_blocks = h_blocks * v_blocks;
s->packet_size = 4 + nb_blocks * (2 + 3 * BLOCK_WIDTH * BLOCK_HEIGHT);
s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);
if (!s->encbuffer) {
@ -229,7 +239,8 @@ static int flashsv_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
I_frame = 1;
}
if ((res = ff_alloc_packet(avctx, pkt, s->image_width * s->image_height * 3)) < 0)
res = ff_alloc_packet(avctx, pkt, s->packet_size);
if (res < 0)
return res;
pkt->size = encode_bitstream(s, p, pkt->data, pkt->size, opt_w * 16, opt_h * 16,