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
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
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                                    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    if (buf_size < 4)
117        return -1;
118
119    init_get_bits(&gb, buf, buf_size * 8);
120
121    /* start to parse the bitstream */
122    s->block_width = 16* (get_bits(&gb, 4)+1);
123    s->image_width =     get_bits(&gb,12);
124    s->block_height= 16* (get_bits(&gb, 4)+1);
125    s->image_height=     get_bits(&gb,12);
126
127    /* calculate amount of blocks and the size of the border blocks */
128    h_blocks = s->image_width / s->block_width;
129    h_part = s->image_width % s->block_width;
130    v_blocks = s->image_height / s->block_height;
131    v_part = s->image_height % s->block_height;
132
133    /* the block size could change between frames, make sure the buffer
134     * is large enough, if not, get a larger one */
135    if(s->block_size < s->block_width*s->block_height) {
136        if (s->tmpblock != NULL)
137            av_free(s->tmpblock);
138        if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
139            av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
140            return -1;
141        }
142    }
143    s->block_size = s->block_width*s->block_height;
144
145    /* init the image size once */
146    if((avctx->width==0) && (avctx->height==0)){
147        avctx->width = s->image_width;
148        avctx->height = s->image_height;
149    }
150
151    /* check for changes of image width and image height */
152    if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
153        av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
154        av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d  vs  ch = %d, cv = %d\n",avctx->height,
155        avctx->width,s->image_height,s->image_width);
156        return -1;
157    }
158
159    av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
160        s->image_width, s->image_height, s->block_width, s->block_height,
161        h_blocks, v_blocks, h_part, v_part);
162
163    s->frame.reference = 1;
164    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
165    if(avctx->reget_buffer(avctx, &s->frame) < 0){
166      av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
167      return -1;
168    }
169
170    /* loop over all block columns */
171    for (j = 0; j < v_blocks + (v_part?1:0); j++)
172    {
173
174        int hp = j*s->block_height; // horiz position in frame
175        int hs = (j<v_blocks)?s->block_height:v_part; // size of block
176
177
178        /* loop over all block rows */
179        for (i = 0; i < h_blocks + (h_part?1:0); i++)
180        {
181            int wp = i*s->block_width; // vert position in frame
182            int ws = (i<h_blocks)?s->block_width:h_part; // size of block
183
184            /* get the size of the compressed zlib chunk */
185            int size = get_bits(&gb, 16);
186            if (8 * size > get_bits_left(&gb)) {
187                avctx->release_buffer(avctx, &s->frame);
188                s->frame.data[0] = NULL;
189                return -1;
190            }
191
192            if (size == 0) {
193                /* no change, don't do anything */
194            } else {
195                /* decompress block */
196                int ret = inflateReset(&(s->zstream));
197                if (ret != Z_OK)
198                {
199                    av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
200                    /* return -1; */
201                }
202                s->zstream.next_in = buf+(get_bits_count(&gb)/8);
203                s->zstream.avail_in = size;
204                s->zstream.next_out = s->tmpblock;
205                s->zstream.avail_out = s->block_size*3;
206                ret = inflate(&(s->zstream), Z_FINISH);
207                if (ret == Z_DATA_ERROR)
208                {
209                    av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
210                    inflateSync(&(s->zstream));
211                    ret = inflate(&(s->zstream), Z_FINISH);
212                }
213
214                if ((ret != Z_OK) && (ret != Z_STREAM_END))
215                {
216                    av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
217                    /* return -1; */
218                }
219                copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
220                skip_bits_long(&gb, 8*size);   /* skip the consumed bits */
221            }
222        }
223    }
224
225    *data_size = sizeof(AVFrame);
226    *(AVFrame*)data = s->frame;
227
228    if ((get_bits_count(&gb)/8) != buf_size)
229        av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
230            buf_size, (get_bits_count(&gb)/8));
231
232    /* report that the buffer was completely consumed */
233    return buf_size;
234}
235
236
237static av_cold int flashsv_decode_end(AVCodecContext *avctx)
238{
239    FlashSVContext *s = avctx->priv_data;
240    inflateEnd(&(s->zstream));
241    /* release the frame if needed */
242    if (s->frame.data[0])
243        avctx->release_buffer(avctx, &s->frame);
244
245    /* free the tmpblock */
246    if (s->tmpblock != NULL)
247        av_free(s->tmpblock);
248
249    return 0;
250}
251
252
253AVCodec flashsv_decoder = {
254    "flashsv",
255    AVMEDIA_TYPE_VIDEO,
256    CODEC_ID_FLASHSV,
257    sizeof(FlashSVContext),
258    flashsv_decode_init,
259    NULL,
260    flashsv_decode_end,
261    flashsv_decode_frame,
262    CODEC_CAP_DR1,
263    .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
264    .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
265};
266