2 * Flash Screen Video decoder
3 * Copyright (C) 2004 Alex Beregszaszi
4 * Copyright (C) 2006 Benjamin Larsson
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * @file libavcodec/flashsv.c
25 * Flash Screen Video decoder
26 * @author Alex Beregszaszi
27 * @author Benjamin Larsson
30 /* Bitstream description
31 * The picture is divided into blocks that are zlib compressed.
33 * The decoder is fed complete frames, the frameheader contains:
34 * 4bits of block width
35 * 12bits of frame width
36 * 4bits of block height
37 * 12bits of frame height
39 * Directly after the header are the compressed blocks. The blocks
40 * have their compressed size represented with 16bits in the beginnig.
41 * If the size = 0 then the block is unchanged from the previous frame.
42 * All blocks are decompressed until the buffer is consumed.
44 * Encoding ideas, a basic encoder would just use a fixed block size.
45 * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
46 * have to be quadratic. A brute force search with a set of diffrent
47 * block sizes should give a better result then to just use a fixed size.
58 typedef struct FlashSVContext {
59 AVCodecContext *avctx;
61 int image_width, image_height;
62 int block_width, block_height;
69 static void copy_region(uint8_t *sptr, uint8_t *dptr,
70 int dx, int dy, int h, int w, int stride)
74 for (i = dx+h; i > dx; i--)
76 memcpy(dptr+(i*stride)+dy*3, sptr, w*3);
82 static av_cold int flashsv_decode_init(AVCodecContext *avctx)
84 FlashSVContext *s = avctx->priv_data;
85 int zret; // Zlib return code
88 s->zstream.zalloc = Z_NULL;
89 s->zstream.zfree = Z_NULL;
90 s->zstream.opaque = Z_NULL;
91 zret = inflateInit(&(s->zstream));
93 av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
96 avctx->pix_fmt = PIX_FMT_BGR24;
97 s->frame.data[0] = NULL;
103 static int flashsv_decode_frame(AVCodecContext *avctx,
104 void *data, int *data_size,
107 const uint8_t *buf = avpkt->data;
108 int buf_size = avpkt->size;
109 FlashSVContext *s = avctx->priv_data;
110 int h_blocks, v_blocks, h_part, v_part, i, j;
113 /* no supplementary picture */
117 init_get_bits(&gb, buf, buf_size * 8);
119 /* start to parse the bitstream */
120 s->block_width = 16* (get_bits(&gb, 4)+1);
121 s->image_width = get_bits(&gb,12);
122 s->block_height= 16* (get_bits(&gb, 4)+1);
123 s->image_height= get_bits(&gb,12);
125 /* calculate amount of blocks and the size of the border blocks */
126 h_blocks = s->image_width / s->block_width;
127 h_part = s->image_width % s->block_width;
128 v_blocks = s->image_height / s->block_height;
129 v_part = s->image_height % s->block_height;
131 /* the block size could change between frames, make sure the buffer
132 * is large enough, if not, get a larger one */
133 if(s->block_size < s->block_width*s->block_height) {
134 if (s->tmpblock != NULL)
135 av_free(s->tmpblock);
136 if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
137 av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
141 s->block_size = s->block_width*s->block_height;
143 /* init the image size once */
144 if((avctx->width==0) && (avctx->height==0)){
145 avctx->width = s->image_width;
146 avctx->height = s->image_height;
149 /* check for changes of image width and image height */
150 if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
151 av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
152 av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d vs ch = %d, cv = %d\n",avctx->height,
153 avctx->width,s->image_height,s->image_width);
157 av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
158 s->image_width, s->image_height, s->block_width, s->block_height,
159 h_blocks, v_blocks, h_part, v_part);
161 s->frame.reference = 1;
162 s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
163 if(avctx->reget_buffer(avctx, &s->frame) < 0){
164 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
168 /* loop over all block columns */
169 for (j = 0; j < v_blocks + (v_part?1:0); j++)
172 int hp = j*s->block_height; // horiz position in frame
173 int hs = (j<v_blocks)?s->block_height:v_part; // size of block
176 /* loop over all block rows */
177 for (i = 0; i < h_blocks + (h_part?1:0); i++)
179 int wp = i*s->block_width; // vert position in frame
180 int ws = (i<h_blocks)?s->block_width:h_part; // size of block
182 /* get the size of the compressed zlib chunk */
183 int size = get_bits(&gb, 16);
186 /* no change, don't do anything */
188 /* decompress block */
189 int ret = inflateReset(&(s->zstream));
192 av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
195 s->zstream.next_in = buf+(get_bits_count(&gb)/8);
196 s->zstream.avail_in = size;
197 s->zstream.next_out = s->tmpblock;
198 s->zstream.avail_out = s->block_size*3;
199 ret = inflate(&(s->zstream), Z_FINISH);
200 if (ret == Z_DATA_ERROR)
202 av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
203 inflateSync(&(s->zstream));
204 ret = inflate(&(s->zstream), Z_FINISH);
207 if ((ret != Z_OK) && (ret != Z_STREAM_END))
209 av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
212 copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
213 skip_bits_long(&gb, 8*size); /* skip the consumed bits */
218 *data_size = sizeof(AVFrame);
219 *(AVFrame*)data = s->frame;
221 if ((get_bits_count(&gb)/8) != buf_size)
222 av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
223 buf_size, (get_bits_count(&gb)/8));
225 /* report that the buffer was completely consumed */
230 static av_cold int flashsv_decode_end(AVCodecContext *avctx)
232 FlashSVContext *s = avctx->priv_data;
233 inflateEnd(&(s->zstream));
234 /* release the frame if needed */
235 if (s->frame.data[0])
236 avctx->release_buffer(avctx, &s->frame);
238 /* free the tmpblock */
239 if (s->tmpblock != NULL)
240 av_free(s->tmpblock);
246 AVCodec flashsv_decoder = {
250 sizeof(FlashSVContext),
254 flashsv_decode_frame,
256 .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
257 .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),