266 lines
8.4 KiB
C
266 lines
8.4 KiB
C
/*
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* Flash Screen Video decoder
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* Copyright (C) 2004 Alex Beregszaszi
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* Copyright (C) 2006 Benjamin Larsson
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Flash Screen Video decoder
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* @author Alex Beregszaszi
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* @author Benjamin Larsson
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*/
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/* Bitstream description
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* The picture is divided into blocks that are zlib compressed.
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*
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* The decoder is fed complete frames, the frameheader contains:
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* 4bits of block width
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* 12bits of frame width
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* 4bits of block height
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* 12bits of frame height
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*
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* Directly after the header are the compressed blocks. The blocks
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* have their compressed size represented with 16bits in the beginnig.
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* If the size = 0 then the block is unchanged from the previous frame.
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* All blocks are decompressed until the buffer is consumed.
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*
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* Encoding ideas, a basic encoder would just use a fixed block size.
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* Block sizes can be multipels of 16, from 16 to 256. The blocks don't
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* have to be quadratic. A brute force search with a set of diffrent
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* block sizes should give a better result then to just use a fixed size.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "avcodec.h"
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#include "get_bits.h"
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#include <zlib.h>
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typedef struct FlashSVContext {
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AVCodecContext *avctx;
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AVFrame frame;
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int image_width, image_height;
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int block_width, block_height;
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uint8_t* tmpblock;
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int block_size;
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z_stream zstream;
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} FlashSVContext;
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static void copy_region(uint8_t *sptr, uint8_t *dptr,
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int dx, int dy, int h, int w, int stride)
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{
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int i;
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for (i = dx+h; i > dx; i--)
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{
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memcpy(dptr+(i*stride)+dy*3, sptr, w*3);
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sptr += w*3;
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}
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}
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static av_cold int flashsv_decode_init(AVCodecContext *avctx)
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{
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FlashSVContext *s = avctx->priv_data;
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int zret; // Zlib return code
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s->avctx = avctx;
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s->zstream.zalloc = Z_NULL;
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s->zstream.zfree = Z_NULL;
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s->zstream.opaque = Z_NULL;
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zret = inflateInit(&(s->zstream));
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if (zret != Z_OK) {
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av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
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return 1;
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}
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avctx->pix_fmt = PIX_FMT_BGR24;
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s->frame.data[0] = NULL;
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return 0;
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}
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static int flashsv_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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AVPacket *avpkt)
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{
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const uint8_t *buf = avpkt->data;
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int buf_size = avpkt->size;
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FlashSVContext *s = avctx->priv_data;
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int h_blocks, v_blocks, h_part, v_part, i, j;
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GetBitContext gb;
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/* no supplementary picture */
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if (buf_size == 0)
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return 0;
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if (buf_size < 4)
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return -1;
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init_get_bits(&gb, buf, buf_size * 8);
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/* start to parse the bitstream */
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s->block_width = 16* (get_bits(&gb, 4)+1);
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s->image_width = get_bits(&gb,12);
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s->block_height= 16* (get_bits(&gb, 4)+1);
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s->image_height= get_bits(&gb,12);
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/* calculate amount of blocks and the size of the border blocks */
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h_blocks = s->image_width / s->block_width;
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h_part = s->image_width % s->block_width;
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v_blocks = s->image_height / s->block_height;
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v_part = s->image_height % s->block_height;
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/* the block size could change between frames, make sure the buffer
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* is large enough, if not, get a larger one */
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if(s->block_size < s->block_width*s->block_height) {
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if (s->tmpblock != NULL)
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av_free(s->tmpblock);
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if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
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av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
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return -1;
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}
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}
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s->block_size = s->block_width*s->block_height;
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/* init the image size once */
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if((avctx->width==0) && (avctx->height==0)){
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avctx->width = s->image_width;
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avctx->height = s->image_height;
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}
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/* check for changes of image width and image height */
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if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
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av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
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av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d vs ch = %d, cv = %d\n",avctx->height,
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avctx->width,s->image_height,s->image_width);
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return -1;
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}
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av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
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s->image_width, s->image_height, s->block_width, s->block_height,
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h_blocks, v_blocks, h_part, v_part);
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s->frame.reference = 1;
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s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
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if(avctx->reget_buffer(avctx, &s->frame) < 0){
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av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
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return -1;
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}
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/* loop over all block columns */
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for (j = 0; j < v_blocks + (v_part?1:0); j++)
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{
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int hp = j*s->block_height; // horiz position in frame
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int hs = (j<v_blocks)?s->block_height:v_part; // size of block
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/* loop over all block rows */
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for (i = 0; i < h_blocks + (h_part?1:0); i++)
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{
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int wp = i*s->block_width; // vert position in frame
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int ws = (i<h_blocks)?s->block_width:h_part; // size of block
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/* get the size of the compressed zlib chunk */
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int size = get_bits(&gb, 16);
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if (8 * size > get_bits_left(&gb)) {
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avctx->release_buffer(avctx, &s->frame);
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s->frame.data[0] = NULL;
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return -1;
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}
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if (size == 0) {
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/* no change, don't do anything */
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} else {
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/* decompress block */
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int ret = inflateReset(&(s->zstream));
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if (ret != Z_OK)
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{
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av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
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/* return -1; */
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}
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s->zstream.next_in = buf+(get_bits_count(&gb)/8);
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s->zstream.avail_in = size;
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s->zstream.next_out = s->tmpblock;
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s->zstream.avail_out = s->block_size*3;
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ret = inflate(&(s->zstream), Z_FINISH);
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if (ret == Z_DATA_ERROR)
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{
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av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
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inflateSync(&(s->zstream));
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ret = inflate(&(s->zstream), Z_FINISH);
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}
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if ((ret != Z_OK) && (ret != Z_STREAM_END))
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{
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av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
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/* return -1; */
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}
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copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
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skip_bits_long(&gb, 8*size); /* skip the consumed bits */
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}
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}
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}
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*data_size = sizeof(AVFrame);
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*(AVFrame*)data = s->frame;
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if ((get_bits_count(&gb)/8) != buf_size)
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av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
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buf_size, (get_bits_count(&gb)/8));
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/* report that the buffer was completely consumed */
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return buf_size;
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}
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static av_cold int flashsv_decode_end(AVCodecContext *avctx)
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{
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FlashSVContext *s = avctx->priv_data;
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inflateEnd(&(s->zstream));
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/* release the frame if needed */
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if (s->frame.data[0])
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avctx->release_buffer(avctx, &s->frame);
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/* free the tmpblock */
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if (s->tmpblock != NULL)
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av_free(s->tmpblock);
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return 0;
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}
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AVCodec flashsv_decoder = {
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"flashsv",
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AVMEDIA_TYPE_VIDEO,
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CODEC_ID_FLASHSV,
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sizeof(FlashSVContext),
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flashsv_decode_init,
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NULL,
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flashsv_decode_end,
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flashsv_decode_frame,
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CODEC_CAP_DR1,
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.pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
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.long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
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};
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