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 "bitstream.h"
55
56#include <zlib.h>
57
58typedef 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
69static 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
82static 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
103static int flashsv_decode_frame(AVCodecContext *avctx,
104                                    void *data, int *data_size,
105                                    const uint8_t *buf, int buf_size)
106{
107    FlashSVContext *s = avctx->priv_data;
108    int h_blocks, v_blocks, h_part, v_part, i, j;
109    GetBitContext gb;
110
111    /* no supplementary picture */
112    if (buf_size == 0)
113        return 0;
114
115    if(s->frame.data[0])
116            avctx->release_buffer(avctx, &s->frame);
117
118    init_get_bits(&gb, buf, buf_size * 8);
119
120    /* start to parse the bitstream */
121    s->block_width = 16* (get_bits(&gb, 4)+1);
122    s->image_width =     get_bits(&gb,12);
123    s->block_height= 16* (get_bits(&gb, 4)+1);
124    s->image_height=     get_bits(&gb,12);
125
126    /* calculate amount of blocks and the size of the border blocks */
127    h_blocks = s->image_width / s->block_width;
128    h_part = s->image_width % s->block_width;
129    v_blocks = s->image_height / s->block_height;
130    v_part = s->image_height % s->block_height;
131
132    /* the block size could change between frames, make sure the buffer
133     * is large enough, if not, get a larger one */
134    if(s->block_size < s->block_width*s->block_height) {
135        if (s->tmpblock != NULL)
136            av_free(s->tmpblock);
137        if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
138            av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
139            return -1;
140        }
141    }
142    s->block_size = s->block_width*s->block_height;
143
144    /* init the image size once */
145    if((avctx->width==0) && (avctx->height==0)){
146        avctx->width = s->image_width;
147        avctx->height = s->image_height;
148    }
149
150    /* check for changes of image width and image height */
151    if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
152        av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
153        av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d  vs  ch = %d, cv = %d\n",avctx->height,
154        avctx->width,s->image_height,s->image_width);
155        return -1;
156    }
157
158    av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
159        s->image_width, s->image_height, s->block_width, s->block_height,
160        h_blocks, v_blocks, h_part, v_part);
161
162    s->frame.reference = 1;
163    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
164    if (avctx->get_buffer(avctx, &s->frame) < 0) {
165        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
166        return -1;
167    }
168
169    /* loop over all block columns */
170    for (j = 0; j < v_blocks + (v_part?1:0); j++)
171    {
172
173        int hp = j*s->block_height; // horiz position in frame
174        int hs = (j<v_blocks)?s->block_height:v_part; // size of block
175
176
177        /* loop over all block rows */
178        for (i = 0; i < h_blocks + (h_part?1:0); i++)
179        {
180            int wp = i*s->block_width; // vert position in frame
181            int ws = (i<h_blocks)?s->block_width:h_part; // size of block
182
183            /* get the size of the compressed zlib chunk */
184            int size = get_bits(&gb, 16);
185
186            if (size == 0) {
187                /* no change, don't do anything */
188            } else {
189                /* decompress block */
190                int ret = inflateReset(&(s->zstream));
191                if (ret != Z_OK)
192                {
193                    av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
194                    /* return -1; */
195                }
196                s->zstream.next_in = buf+(get_bits_count(&gb)/8);
197                s->zstream.avail_in = size;
198                s->zstream.next_out = s->tmpblock;
199                s->zstream.avail_out = s->block_size*3;
200                ret = inflate(&(s->zstream), Z_FINISH);
201                if (ret == Z_DATA_ERROR)
202                {
203                    av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
204                    inflateSync(&(s->zstream));
205                    ret = inflate(&(s->zstream), Z_FINISH);
206                }
207
208                if ((ret != Z_OK) && (ret != Z_STREAM_END))
209                {
210                    av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
211                    /* return -1; */
212                }
213                copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
214                skip_bits_long(&gb, 8*size);   /* skip the consumed bits */
215            }
216        }
217    }
218
219    *data_size = sizeof(AVFrame);
220    *(AVFrame*)data = s->frame;
221
222    if ((get_bits_count(&gb)/8) != buf_size)
223        av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
224            buf_size, (get_bits_count(&gb)/8));
225
226    /* report that the buffer was completely consumed */
227    return buf_size;
228}
229
230
231static av_cold int flashsv_decode_end(AVCodecContext *avctx)
232{
233    FlashSVContext *s = avctx->priv_data;
234    inflateEnd(&(s->zstream));
235    /* release the frame if needed */
236    if (s->frame.data[0])
237        avctx->release_buffer(avctx, &s->frame);
238
239    /* free the tmpblock */
240    if (s->tmpblock != NULL)
241        av_free(s->tmpblock);
242
243    return 0;
244}
245
246
247AVCodec flashsv_decoder = {
248    "flashsv",
249    CODEC_TYPE_VIDEO,
250    CODEC_ID_FLASHSV,
251    sizeof(FlashSVContext),
252    flashsv_decode_init,
253    NULL,
254    flashsv_decode_end,
255    flashsv_decode_frame,
256    CODEC_CAP_DR1,
257    .pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
258    .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
259};
260