1 /*
2  * CamStudio decoder
3  * Copyright (c) 2006 Reimar Doeffinger
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 #include <stdio.h>
22 #include <stdlib.h>
23 
24 #include "avcodec.h"
25 #include "codec_internal.h"
26 #include "internal.h"
27 #include "libavutil/common.h"
28 
29 #if CONFIG_ZLIB
30 #include <zlib.h>
31 #endif
32 #include "libavutil/lzo.h"
33 
34 typedef struct CamStudioContext {
35     AVFrame *pic;
36     int linelen, height, bpp;
37     unsigned int decomp_size;
38     unsigned char* decomp_buf;
39 } CamStudioContext;
40 
copy_frame_default(AVFrame *f, const uint8_t *src, int linelen, int height)41 static void copy_frame_default(AVFrame *f, const uint8_t *src,
42                                int linelen, int height)
43 {
44     int i, src_stride = FFALIGN(linelen, 4);
45     uint8_t *dst = f->data[0];
46     dst += (height - 1) * f->linesize[0];
47     for (i = height; i; i--) {
48         memcpy(dst, src, linelen);
49         src += src_stride;
50         dst -= f->linesize[0];
51     }
52 }
53 
add_frame_default(AVFrame *f, const uint8_t *src, int linelen, int height)54 static void add_frame_default(AVFrame *f, const uint8_t *src,
55                               int linelen, int height)
56 {
57     int i, j, src_stride = FFALIGN(linelen, 4);
58     uint8_t *dst = f->data[0];
59     dst += (height - 1) * f->linesize[0];
60     for (i = height; i; i--) {
61         for (j = linelen; j; j--)
62             *dst++ += *src++;
63         src += src_stride - linelen;
64         dst -= f->linesize[0] + linelen;
65     }
66 }
67 
decode_frame(AVCodecContext *avctx, AVFrame *rframe, int *got_frame, AVPacket *avpkt)68 static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
69                         int *got_frame, AVPacket *avpkt)
70 {
71     const uint8_t *buf = avpkt->data;
72     int buf_size = avpkt->size;
73     CamStudioContext *c = avctx->priv_data;
74     int ret;
75     int bpp = avctx->bits_per_coded_sample / 8;
76     int bugdelta = FFALIGN(avctx->width * bpp, 4)       * avctx->height
77                  -        (avctx->width     & ~3) * bpp * avctx->height;
78 
79     if (buf_size < 2) {
80         av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
81         return AVERROR_INVALIDDATA;
82     }
83 
84     if ((ret = ff_reget_buffer(avctx, c->pic, 0)) < 0)
85         return ret;
86 
87     // decompress data
88     switch ((buf[0] >> 1) & 7) {
89     case 0: { // lzo compression
90         int outlen = c->decomp_size, inlen = buf_size - 2;
91         if (av_lzo1x_decode(c->decomp_buf, &outlen, &buf[2], &inlen) || (outlen && outlen != bugdelta)) {
92             av_log(avctx, AV_LOG_ERROR, "error during lzo decompression\n");
93             return AVERROR_INVALIDDATA;
94         }
95         break;
96     }
97     case 1: { // zlib compression
98 #if CONFIG_ZLIB
99         unsigned long dlen = c->decomp_size;
100         if (uncompress(c->decomp_buf, &dlen, &buf[2], buf_size - 2) != Z_OK || (dlen != c->decomp_size && dlen != c->decomp_size - bugdelta)) {
101             av_log(avctx, AV_LOG_ERROR, "error during zlib decompression\n");
102             return AVERROR_INVALIDDATA;
103         }
104         break;
105 #else
106         av_log(avctx, AV_LOG_ERROR, "compiled without zlib support\n");
107         return AVERROR(ENOSYS);
108 #endif
109     }
110     default:
111         av_log(avctx, AV_LOG_ERROR, "unknown compression\n");
112         return AVERROR_INVALIDDATA;
113     }
114 
115     // flip upside down, add difference frame
116     if (buf[0] & 1) { // keyframe
117         c->pic->pict_type = AV_PICTURE_TYPE_I;
118         c->pic->key_frame = 1;
119               copy_frame_default(c->pic, c->decomp_buf,
120                                  c->linelen, c->height);
121     } else {
122         c->pic->pict_type = AV_PICTURE_TYPE_P;
123         c->pic->key_frame = 0;
124               add_frame_default(c->pic, c->decomp_buf,
125                                 c->linelen, c->height);
126     }
127 
128     *got_frame = 1;
129     if ((ret = av_frame_ref(rframe, c->pic)) < 0)
130         return ret;
131 
132     return buf_size;
133 }
134 
decode_init(AVCodecContext *avctx)135 static av_cold int decode_init(AVCodecContext *avctx)
136 {
137     CamStudioContext *c = avctx->priv_data;
138     int stride;
139     switch (avctx->bits_per_coded_sample) {
140     case 16: avctx->pix_fmt = AV_PIX_FMT_RGB555LE; break;
141     case 24: avctx->pix_fmt = AV_PIX_FMT_BGR24; break;
142     case 32: avctx->pix_fmt = AV_PIX_FMT_BGR0; break;
143     default:
144         av_log(avctx, AV_LOG_ERROR,
145                "CamStudio codec error: invalid depth %i bpp\n",
146                avctx->bits_per_coded_sample);
147         return AVERROR_INVALIDDATA;
148     }
149     c->bpp = avctx->bits_per_coded_sample;
150     c->linelen = avctx->width * avctx->bits_per_coded_sample / 8;
151     c->height = avctx->height;
152     stride = FFALIGN(c->linelen, 4);
153     c->decomp_size = c->height * stride;
154     c->decomp_buf = av_malloc(c->decomp_size + AV_LZO_OUTPUT_PADDING);
155     if (!c->decomp_buf) {
156         av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
157         return AVERROR(ENOMEM);
158     }
159     c->pic = av_frame_alloc();
160     if (!c->pic)
161         return AVERROR(ENOMEM);
162     return 0;
163 }
164 
decode_end(AVCodecContext *avctx)165 static av_cold int decode_end(AVCodecContext *avctx)
166 {
167     CamStudioContext *c = avctx->priv_data;
168     av_freep(&c->decomp_buf);
169     av_frame_free(&c->pic);
170     return 0;
171 }
172 
173 const FFCodec ff_cscd_decoder = {
174     .p.name         = "camstudio",
175     .p.long_name    = NULL_IF_CONFIG_SMALL("CamStudio"),
176     .p.type         = AVMEDIA_TYPE_VIDEO,
177     .p.id           = AV_CODEC_ID_CSCD,
178     .priv_data_size = sizeof(CamStudioContext),
179     .init           = decode_init,
180     .close          = decode_end,
181     FF_CODEC_DECODE_CB(decode_frame),
182     .p.capabilities = AV_CODEC_CAP_DR1,
183     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
184 };
185