Statistics
| Branch: | Revision:

ffmpeg / libavcodec / flashsv.c @ 9106a698

History | View | Annotate | Download (8.27 KB)

1
/*
2
 * Flash Screen Video decoder
3
 * Copyright (C) 2004 Alex Beregszaszi
4
 * Copyright (C) 2006 Benjamin Larsson
5
 *
6
 * This file is part of FFmpeg.
7
 *
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.
12
 *
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.
17
 *
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
21
 */
22

    
23
/**
24
 * @file libavcodec/flashsv.c
25
 * Flash Screen Video decoder
26
 * @author Alex Beregszaszi
27
 * @author Benjamin Larsson
28
 */
29

    
30
/* Bitstream description
31
 * The picture is divided into blocks that are zlib compressed.
32
 *
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
38
 *
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.
43
 *
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.
48
 */
49

    
50
#include <stdio.h>
51
#include <stdlib.h>
52

    
53
#include "avcodec.h"
54
#include "get_bits.h"
55

    
56
#include <zlib.h>
57

    
58
typedef struct FlashSVContext {
59
    AVCodecContext *avctx;
60
    AVFrame frame;
61
    int image_width, image_height;
62
    int block_width, block_height;
63
    uint8_t* tmpblock;
64
    int block_size;
65
    z_stream zstream;
66
} FlashSVContext;
67

    
68

    
69
static void copy_region(uint8_t *sptr, uint8_t *dptr,
70
        int dx, int dy, int h, int w, int stride)
71
{
72
    int i;
73

    
74
    for (i = dx+h; i > dx; i--)
75
    {
76
        memcpy(dptr+(i*stride)+dy*3, sptr, w*3);
77
        sptr += w*3;
78
    }
79
}
80

    
81

    
82
static av_cold int flashsv_decode_init(AVCodecContext *avctx)
83
{
84
    FlashSVContext *s = avctx->priv_data;
85
    int zret; // Zlib return code
86

    
87
    s->avctx = avctx;
88
    s->zstream.zalloc = Z_NULL;
89
    s->zstream.zfree = Z_NULL;
90
    s->zstream.opaque = Z_NULL;
91
    zret = inflateInit(&(s->zstream));
92
    if (zret != Z_OK) {
93
        av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
94
        return 1;
95
    }
96
    avctx->pix_fmt = PIX_FMT_BGR24;
97
    s->frame.data[0] = NULL;
98

    
99
    return 0;
100
}
101

    
102

    
103
static int flashsv_decode_frame(AVCodecContext *avctx,
104
                                    void *data, int *data_size,
105
                                    AVPacket *avpkt)
106
{
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;
111
    GetBitContext gb;
112

    
113
    /* no supplementary picture */
114
    if (buf_size == 0)
115
        return 0;
116

    
117
    if(s->frame.data[0])
118
            avctx->release_buffer(avctx, &s->frame);
119

    
120
    init_get_bits(&gb, buf, buf_size * 8);
121

    
122
    /* start to parse the bitstream */
123
    s->block_width = 16* (get_bits(&gb, 4)+1);
124
    s->image_width =     get_bits(&gb,12);
125
    s->block_height= 16* (get_bits(&gb, 4)+1);
126
    s->image_height=     get_bits(&gb,12);
127

    
128
    /* calculate amount of blocks and the size of the border blocks */
129
    h_blocks = s->image_width / s->block_width;
130
    h_part = s->image_width % s->block_width;
131
    v_blocks = s->image_height / s->block_height;
132
    v_part = s->image_height % s->block_height;
133

    
134
    /* the block size could change between frames, make sure the buffer
135
     * is large enough, if not, get a larger one */
136
    if(s->block_size < s->block_width*s->block_height) {
137
        if (s->tmpblock != NULL)
138
            av_free(s->tmpblock);
139
        if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
140
            av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
141
            return -1;
142
        }
143
    }
144
    s->block_size = s->block_width*s->block_height;
145

    
146
    /* init the image size once */
147
    if((avctx->width==0) && (avctx->height==0)){
148
        avctx->width = s->image_width;
149
        avctx->height = s->image_height;
150
    }
151

    
152
    /* check for changes of image width and image height */
153
    if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
154
        av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
155
        av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d  vs  ch = %d, cv = %d\n",avctx->height,
156
        avctx->width,s->image_height,s->image_width);
157
        return -1;
158
    }
159

    
160
    av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
161
        s->image_width, s->image_height, s->block_width, s->block_height,
162
        h_blocks, v_blocks, h_part, v_part);
163

    
164
    s->frame.reference = 1;
165
    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
166
    if (avctx->get_buffer(avctx, &s->frame) < 0) {
167
        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
168
        return -1;
169
    }
170

    
171
    /* loop over all block columns */
172
    for (j = 0; j < v_blocks + (v_part?1:0); j++)
173
    {
174

    
175
        int hp = j*s->block_height; // horiz position in frame
176
        int hs = (j<v_blocks)?s->block_height:v_part; // size of block
177

    
178

    
179
        /* loop over all block rows */
180
        for (i = 0; i < h_blocks + (h_part?1:0); i++)
181
        {
182
            int wp = i*s->block_width; // vert position in frame
183
            int ws = (i<h_blocks)?s->block_width:h_part; // size of block
184

    
185
            /* get the size of the compressed zlib chunk */
186
            int size = get_bits(&gb, 16);
187

    
188
            if (size == 0) {
189
                /* no change, don't do anything */
190
            } else {
191
                /* decompress block */
192
                int ret = inflateReset(&(s->zstream));
193
                if (ret != Z_OK)
194
                {
195
                    av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
196
                    /* return -1; */
197
                }
198
                s->zstream.next_in = buf+(get_bits_count(&gb)/8);
199
                s->zstream.avail_in = size;
200
                s->zstream.next_out = s->tmpblock;
201
                s->zstream.avail_out = s->block_size*3;
202
                ret = inflate(&(s->zstream), Z_FINISH);
203
                if (ret == Z_DATA_ERROR)
204
                {
205
                    av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
206
                    inflateSync(&(s->zstream));
207
                    ret = inflate(&(s->zstream), Z_FINISH);
208
                }
209

    
210
                if ((ret != Z_OK) && (ret != Z_STREAM_END))
211
                {
212
                    av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
213
                    /* return -1; */
214
                }
215
                copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
216
                skip_bits_long(&gb, 8*size);   /* skip the consumed bits */
217
            }
218
        }
219
    }
220

    
221
    *data_size = sizeof(AVFrame);
222
    *(AVFrame*)data = s->frame;
223

    
224
    if ((get_bits_count(&gb)/8) != buf_size)
225
        av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
226
            buf_size, (get_bits_count(&gb)/8));
227

    
228
    /* report that the buffer was completely consumed */
229
    return buf_size;
230
}
231

    
232

    
233
static av_cold int flashsv_decode_end(AVCodecContext *avctx)
234
{
235
    FlashSVContext *s = avctx->priv_data;
236
    inflateEnd(&(s->zstream));
237
    /* release the frame if needed */
238
    if (s->frame.data[0])
239
        avctx->release_buffer(avctx, &s->frame);
240

    
241
    /* free the tmpblock */
242
    if (s->tmpblock != NULL)
243
        av_free(s->tmpblock);
244

    
245
    return 0;
246
}
247

    
248

    
249
AVCodec flashsv_decoder = {
250
    "flashsv",
251
    CODEC_TYPE_VIDEO,
252
    CODEC_ID_FLASHSV,
253
    sizeof(FlashSVContext),
254
    flashsv_decode_init,
255
    NULL,
256
    flashsv_decode_end,
257
    flashsv_decode_frame,
258
    CODEC_CAP_DR1,
259
    .pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
260
    .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
261
};