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FFmpeg/libavcodec/flashsv.c

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/*
* Flash Screen Video decoder
* Copyright (C) 2004 Alex Beregszaszi
* Copyright (C) 2006 Benjamin Larsson
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file flashsv.c
* Flash Screen Video decoder
* @author Alex Beregszaszi
* @author Benjamin Larsson
*/
/* Bitstream description
* The picture is divided into blocks that are zlib compressed.
*
* The decoder is fed complete frames, the frameheader contains:
* 4bits of block width
* 12bits of frame width
* 4bits of block height
* 12bits of frame height
*
* Directly after the header are the compressed blocks. The blocks
* have their compressed size represented with 16bits in the beginnig.
* If the size = 0 then the block is unchanged from the previous frame.
* All blocks are decompressed until the buffer is consumed.
*
* Encoding ideas, a basic encoder would just use a fixed block size.
* Block sizes can be multipels of 16, from 16 to 256. The blocks don't
* have to be quadratic. A brute force search with a set of diffrent
* block sizes should give a better result then to just use a fixed size.
*/
#include <stdio.h>
#include <stdlib.h>
#include "common.h"
#include "avcodec.h"
#include "bitstream.h"
#ifdef CONFIG_ZLIB
#include <zlib.h>
#endif
typedef struct FlashSVContext {
AVCodecContext *avctx;
AVFrame frame;
int image_width, image_height;
int block_width, block_height;
uint8_t* tmpblock;
int block_size;
#ifdef CONFIG_ZLIB
z_stream zstream;
#endif
} FlashSVContext;
static void copy_region(uint8_t *sptr, uint8_t *dptr,
int dx, int dy, int h, int w, int stride)
{
int i;
for (i = dx+h; i > dx; i--)
{
memcpy(dptr+(i*stride)+dy*3, sptr, w*3);
sptr += w*3;
}
}
static int flashsv_decode_init(AVCodecContext *avctx)
{
FlashSVContext *s = (FlashSVContext *)avctx->priv_data;
int zret; // Zlib return code
s->avctx = avctx;
#ifdef CONFIG_ZLIB
s->zstream.zalloc = Z_NULL;
s->zstream.zfree = Z_NULL;
s->zstream.opaque = Z_NULL;
zret = inflateInit(&(s->zstream));
if (zret != Z_OK) {
av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
return 1;
}
#else
av_log(avctx, AV_LOG_ERROR, "Zlib support not compiled. Needed for the decoder.\n");
return 1;
#endif
avctx->pix_fmt = PIX_FMT_BGR24;
avctx->has_b_frames = 0;
s->frame.data[0] = NULL;
return 0;
}
static int flashsv_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size)
{
FlashSVContext *s = (FlashSVContext *)avctx->priv_data;
int h_blocks, v_blocks, h_part, v_part, i, j;
GetBitContext gb;
/* no supplementary picture */
if (buf_size == 0)
return 0;
if(s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
init_get_bits(&gb, buf, buf_size * 8);
/* start to parse the bitstream */
s->block_width = 16* (get_bits(&gb, 4)+1);
s->image_width = get_bits(&gb,12);
s->block_height= 16* (get_bits(&gb, 4)+1);
s->image_height= get_bits(&gb,12);
/* calculate amount of blocks and the size of the border blocks */
h_blocks = s->image_width / s->block_width;
h_part = s->image_width % s->block_width;
v_blocks = s->image_height / s->block_height;
v_part = s->image_height % s->block_height;
/* the block size could change between frames, make sure the buffer
* is large enough, if not, get a larger one */
if(s->block_size < s->block_width*s->block_height) {
if (s->tmpblock != NULL)
av_free(s->tmpblock);
s->block_size = s->block_width*s->block_height;
if ((s->tmpblock = av_malloc(3*s->block_size)) == NULL) {
av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
return -1;
}
}
/* init the image size once */
if((avctx->width==0) && (avctx->height==0)){
avctx->width = s->image_width;
avctx->height = s->image_height;
}
/* check for changes of image width and image height */
if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d vs ch = %d, cv = %d\n",avctx->height,
avctx->width,s->image_height,s->image_width);
return -1;
}
av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
s->image_width, s->image_height, s->block_width, s->block_height,
h_blocks, v_blocks, h_part, v_part);
s->frame.reference = 1;
s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
if (avctx->get_buffer(avctx, &s->frame) < 0) {
av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return -1;
}
/* loop over all block columns */
for (j = 0; j < v_blocks + (v_part?1:0); j++)
{
int hp = j*s->block_height; // horiz position in frame
int hs = (j<v_blocks)?s->block_height:v_part; // size of block
/* loop over all block rows */
for (i = 0; i < h_blocks + (h_part?1:0); i++)
{
int wp = i*s->block_width; // vert position in frame
int ws = (i<h_blocks)?s->block_width:h_part; // size of block
/* get the size of the compressed zlib chunk */
int size = get_bits(&gb, 16);
if (size == 0) {
/* no change, don't do anything */
} else {
/* decompress block */
#ifdef CONFIG_ZLIB
int ret = inflateReset(&(s->zstream));
if (ret != Z_OK)
{
av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
/* return -1; */
}
s->zstream.next_in = buf+(get_bits_count(&gb)/8);
s->zstream.avail_in = size;
s->zstream.next_out = s->tmpblock;
s->zstream.avail_out = s->block_size*3;
ret = inflate(&(s->zstream), Z_FINISH);
if (ret == Z_DATA_ERROR)
{
av_log(avctx, AV_LOG_ERROR, "Zlib resync occured\n");
inflateSync(&(s->zstream));
ret = inflate(&(s->zstream), Z_FINISH);
}
if ((ret != Z_OK) && (ret != Z_STREAM_END))
{
av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
/* return -1; */
}
#else
av_log(avctx, AV_LOG_ERROR, "Zlib support not compiled in.\n");
return -1;
#endif
copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
skip_bits(&gb, 8*size); /* skip the consumed bits */
}
}
}
*data_size = sizeof(AVFrame);
*(AVFrame*)data = s->frame;
if ((get_bits_count(&gb)/8) != buf_size)
av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
buf_size, (get_bits_count(&gb)/8));
/* report that the buffer was completely consumed */
return buf_size;
}
static int flashsv_decode_end(AVCodecContext *avctx)
{
FlashSVContext *s = (FlashSVContext *)avctx->priv_data;
#ifdef CONFIG_ZLIB
inflateEnd(&(s->zstream));
#endif
/* release the frame if needed */
if (s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
/* free the tmpblock */
if (s->tmpblock != NULL)
av_free(s->tmpblock);
return 0;
}
AVCodec flashsv_decoder = {
"flashsv",
CODEC_TYPE_VIDEO,
CODEC_ID_FLASHSV,
sizeof(FlashSVContext),
flashsv_decode_init,
NULL,
flashsv_decode_end,
flashsv_decode_frame,
CODEC_CAP_DR1,
.pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, -1},
};