FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
c93.c
Go to the documentation of this file.
1 /*
2  * Interplay C93 demuxer
3  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
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 
22 #include "avformat.h"
23 #include "internal.h"
24 #include "voc.h"
25 #include "libavutil/intreadwrite.h"
26 
27 typedef struct {
28  uint16_t index;
32 
33 typedef struct {
35 
36  C93BlockRecord block_records[512];
38 
39  uint32_t frame_offsets[32];
42 
45 
46 static int probe(AVProbeData *p)
47 {
48  int i;
49  int index = 1;
50  if (p->buf_size < 16)
51  return 0;
52  for (i = 0; i < 16; i += 4) {
53  if (AV_RL16(p->buf + i) != index || !p->buf[i + 2] || !p->buf[i + 3])
54  return 0;
55  index += p->buf[i + 2];
56  }
57  return AVPROBE_SCORE_MAX;
58 }
59 
61 {
62  AVStream *video;
63  AVIOContext *pb = s->pb;
64  C93DemuxContext *c93 = s->priv_data;
65  int i;
66  int framecount = 0;
67 
68  for (i = 0; i < 512; i++) {
69  c93->block_records[i].index = avio_rl16(pb);
70  c93->block_records[i].length = avio_r8(pb);
71  c93->block_records[i].frames = avio_r8(pb);
72  if (c93->block_records[i].frames > 32) {
73  av_log(s, AV_LOG_ERROR, "too many frames in block\n");
74  return AVERROR_INVALIDDATA;
75  }
76  framecount += c93->block_records[i].frames;
77  }
78 
79  /* Audio streams are added if audio packets are found */
81 
82  video = avformat_new_stream(s, NULL);
83  if (!video)
84  return AVERROR(ENOMEM);
85 
87  video->codec->codec_id = AV_CODEC_ID_C93;
88  video->codec->width = 320;
89  video->codec->height = 192;
90  /* 4:3 320x200 with 8 empty lines */
91  video->sample_aspect_ratio = (AVRational) { 5, 6 };
92  avpriv_set_pts_info(video, 64, 2, 25);
93  video->nb_frames = framecount;
94  video->duration = framecount;
95  video->start_time = 0;
96 
97  c93->current_block = 0;
98  c93->current_frame = 0;
99  c93->next_pkt_is_audio = 0;
100  return 0;
101 }
102 
103 #define C93_HAS_PALETTE 0x01
104 #define C93_FIRST_FRAME 0x02
105 
107 {
108  AVIOContext *pb = s->pb;
109  C93DemuxContext *c93 = s->priv_data;
110  C93BlockRecord *br = &c93->block_records[c93->current_block];
111  int datasize;
112  int ret, i;
113 
114  if (c93->next_pkt_is_audio) {
115  c93->current_frame++;
116  c93->next_pkt_is_audio = 0;
117  datasize = avio_rl16(pb);
118  if (datasize > 42) {
119  if (!c93->audio) {
120  c93->audio = avformat_new_stream(s, NULL);
121  if (!c93->audio)
122  return AVERROR(ENOMEM);
124  }
125  avio_skip(pb, 26); /* VOC header */
126  ret = ff_voc_get_packet(s, pkt, c93->audio, datasize - 26);
127  if (ret > 0) {
128  pkt->stream_index = 1;
129  pkt->flags |= AV_PKT_FLAG_KEY;
130  return ret;
131  }
132  }
133  }
134  if (c93->current_frame >= br->frames) {
135  if (c93->current_block >= 511 || !br[1].length)
136  return AVERROR_EOF;
137  br++;
138  c93->current_block++;
139  c93->current_frame = 0;
140  }
141 
142  if (c93->current_frame == 0) {
143  avio_seek(pb, br->index * 2048, SEEK_SET);
144  for (i = 0; i < 32; i++) {
145  c93->frame_offsets[i] = avio_rl32(pb);
146  }
147  }
148 
149  avio_seek(pb,br->index * 2048 +
150  c93->frame_offsets[c93->current_frame], SEEK_SET);
151  datasize = avio_rl16(pb); /* video frame size */
152 
153  ret = av_new_packet(pkt, datasize + 768 + 1);
154  if (ret < 0)
155  return ret;
156  pkt->data[0] = 0;
157  pkt->size = datasize + 1;
158 
159  ret = avio_read(pb, pkt->data + 1, datasize);
160  if (ret < datasize) {
161  ret = AVERROR(EIO);
162  goto fail;
163  }
164 
165  datasize = avio_rl16(pb); /* palette size */
166  if (datasize) {
167  if (datasize != 768) {
168  av_log(s, AV_LOG_ERROR, "invalid palette size %u\n", datasize);
169  ret = AVERROR_INVALIDDATA;
170  goto fail;
171  }
172  pkt->data[0] |= C93_HAS_PALETTE;
173  ret = avio_read(pb, pkt->data + pkt->size, datasize);
174  if (ret < datasize) {
175  ret = AVERROR(EIO);
176  goto fail;
177  }
178  pkt->size += 768;
179  }
180  pkt->stream_index = 0;
181  c93->next_pkt_is_audio = 1;
182 
183  /* only the first frame is guaranteed to not reference previous frames */
184  if (c93->current_block == 0 && c93->current_frame == 0) {
185  pkt->flags |= AV_PKT_FLAG_KEY;
186  pkt->data[0] |= C93_FIRST_FRAME;
187  }
188  return 0;
189 
190  fail:
191  av_free_packet(pkt);
192  return ret;
193 }
194 
196  .name = "c93",
197  .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
198  .priv_data_size = sizeof(C93DemuxContext),
199  .read_probe = probe,
202 };