2 * id Quake II CIN File Demuxer
3 * Copyright (c) 2003 The ffmpeg Project
5 * This file is part of Libav.
7 * Libav 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.
12 * Libav 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.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * id Quake II CIN file demuxer by Mike Melanson (melanson@pcisys.net)
25 * For more information about the id CIN format, visit:
26 * http://www.csse.monash.edu.au/~timf/
28 * CIN is a somewhat quirky and ill-defined format. Here are some notes
29 * for anyone trying to understand the technical details of this format:
31 * The format has no definite file signature. This is problematic for a
32 * general-purpose media player that wants to automatically detect file
33 * types. However, a CIN file does start with 5 32-bit numbers that
34 * specify audio and video parameters. This demuxer gets around the lack
35 * of file signature by performing sanity checks on those parameters.
36 * Probabalistically, this is a reasonable solution since the number of
37 * valid combinations of the 5 parameters is a very small subset of the
38 * total 160-bit number space.
40 * Refer to the function idcin_probe() for the precise A/V parameters
41 * that this demuxer allows.
43 * Next, each audio and video frame has a duration of 1/14 sec. If the
44 * audio sample rate is a multiple of the common frequency 22050 Hz it will
45 * divide evenly by 14. However, if the sample rate is 11025 Hz:
46 * 11025 (samples/sec) / 14 (frames/sec) = 787.5 (samples/frame)
47 * The way the CIN stores audio in this case is by storing 787 sample
48 * frames in the first audio frame and 788 sample frames in the second
49 * audio frame. Therefore, the total number of bytes in an audio frame
51 * audio frame #0: 787 * (bytes/sample) * (# channels) bytes in frame
52 * audio frame #1: 788 * (bytes/sample) * (# channels) bytes in frame
53 * audio frame #2: 787 * (bytes/sample) * (# channels) bytes in frame
54 * audio frame #3: 788 * (bytes/sample) * (# channels) bytes in frame
56 * Finally, not all id CIN creation tools agree on the resolution of the
57 * color palette, apparently. Some creation tools specify red, green, and
58 * blue palette components in terms of 6-bit VGA color DAC values which
59 * range from 0..63. Other tools specify the RGB components as full 8-bit
60 * values that range from 0..255. Since there are no markers in the file to
61 * differentiate between the two variants, this demuxer uses the following
63 * - load the 768 palette bytes from disk
64 * - assume that they will need to be shifted left by 2 bits to
65 * transform them from 6-bit values to 8-bit values
66 * - scan through all 768 palette bytes
67 * - if any bytes exceed 63, do not shift the bytes at all before
68 * transmitting them to the video decoder
71 #include "libavutil/intreadwrite.h"
75 #define HUFFMAN_TABLE_SIZE (64 * 1024)
78 typedef struct IdcinDemuxContext {
79 int video_stream_index;
80 int audio_stream_index;
81 int audio_chunk_size1;
82 int audio_chunk_size2;
84 /* demux state variables */
85 int current_audio_chunk;
86 int next_chunk_is_video;
92 static int idcin_probe(AVProbeData *p)
97 * This is what you could call a "probabilistic" file check: id CIN
98 * files don't have a definite file signature. In lieu of such a marker,
99 * perform sanity checks on the 5 32-bit header fields:
100 * width, height: greater than 0, less than or equal to 1024
101 * audio sample rate: greater than or equal to 8000, less than or
102 * equal to 48000, or 0 for no audio
103 * audio sample width (bytes/sample): 0 for no audio, or 1 or 2
104 * audio channels: 0 for no audio, or 1 or 2
107 /* check we have enough data to do all checks, otherwise the
108 0-padding may cause a wrong recognition */
109 if (p->buf_size < 20)
112 /* check the video width */
113 number = AV_RL32(&p->buf[0]);
114 if ((number == 0) || (number > 1024))
117 /* check the video height */
118 number = AV_RL32(&p->buf[4]);
119 if ((number == 0) || (number > 1024))
122 /* check the audio sample rate */
123 number = AV_RL32(&p->buf[8]);
124 if ((number != 0) && ((number < 8000) | (number > 48000)))
127 /* check the audio bytes/sample */
128 number = AV_RL32(&p->buf[12]);
132 /* check the audio channels */
133 number = AV_RL32(&p->buf[16]);
137 /* return half certainly since this check is a bit sketchy */
138 return AVPROBE_SCORE_MAX / 2;
141 static int idcin_read_header(AVFormatContext *s)
143 AVIOContext *pb = s->pb;
144 IdcinDemuxContext *idcin = s->priv_data;
146 unsigned int width, height;
147 unsigned int sample_rate, bytes_per_sample, channels;
149 /* get the 5 header parameters */
150 width = avio_rl32(pb);
151 height = avio_rl32(pb);
152 sample_rate = avio_rl32(pb);
153 bytes_per_sample = avio_rl32(pb);
154 channels = avio_rl32(pb);
156 st = avformat_new_stream(s, NULL);
158 return AVERROR(ENOMEM);
159 avpriv_set_pts_info(st, 33, 1, IDCIN_FPS);
160 idcin->video_stream_index = st->index;
161 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
162 st->codec->codec_id = AV_CODEC_ID_IDCIN;
163 st->codec->codec_tag = 0; /* no fourcc */
164 st->codec->width = width;
165 st->codec->height = height;
167 /* load up the Huffman tables into extradata */
168 st->codec->extradata_size = HUFFMAN_TABLE_SIZE;
169 st->codec->extradata = av_malloc(HUFFMAN_TABLE_SIZE);
170 if (avio_read(pb, st->codec->extradata, HUFFMAN_TABLE_SIZE) !=
174 /* if sample rate is 0, assume no audio */
176 idcin->audio_present = 1;
177 st = avformat_new_stream(s, NULL);
179 return AVERROR(ENOMEM);
180 avpriv_set_pts_info(st, 33, 1, IDCIN_FPS);
181 idcin->audio_stream_index = st->index;
182 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
183 st->codec->codec_tag = 1;
184 st->codec->channels = channels;
185 st->codec->sample_rate = sample_rate;
186 st->codec->bits_per_coded_sample = bytes_per_sample * 8;
187 st->codec->bit_rate = sample_rate * bytes_per_sample * 8 * channels;
188 st->codec->block_align = bytes_per_sample * channels;
189 if (bytes_per_sample == 1)
190 st->codec->codec_id = AV_CODEC_ID_PCM_U8;
192 st->codec->codec_id = AV_CODEC_ID_PCM_S16LE;
194 if (sample_rate % 14 != 0) {
195 idcin->audio_chunk_size1 = (sample_rate / 14) *
196 bytes_per_sample * channels;
197 idcin->audio_chunk_size2 = (sample_rate / 14 + 1) *
198 bytes_per_sample * channels;
200 idcin->audio_chunk_size1 = idcin->audio_chunk_size2 =
201 (sample_rate / 14) * bytes_per_sample * channels;
203 idcin->current_audio_chunk = 0;
205 idcin->audio_present = 1;
207 idcin->next_chunk_is_video = 1;
213 static int idcin_read_packet(AVFormatContext *s,
217 unsigned int command;
218 unsigned int chunk_size;
219 IdcinDemuxContext *idcin = s->priv_data;
220 AVIOContext *pb = s->pb;
223 unsigned char r, g, b;
224 unsigned char palette_buffer[768];
225 uint32_t palette[256];
227 if (s->pb->eof_reached)
230 if (idcin->next_chunk_is_video) {
231 command = avio_rl32(pb);
234 } else if (command == 1) {
235 /* trigger a palette change */
236 if (avio_read(pb, palette_buffer, 768) != 768)
238 /* scale the palette as necessary */
240 for (i = 0; i < 768; i++)
241 if (palette_buffer[i] > 63) {
246 for (i = 0; i < 256; i++) {
247 r = palette_buffer[i * 3 ] << palette_scale;
248 g = palette_buffer[i * 3 + 1] << palette_scale;
249 b = palette_buffer[i * 3 + 2] << palette_scale;
250 palette[i] = (r << 16) | (g << 8) | (b);
254 chunk_size = avio_rl32(pb);
255 /* skip the number of decoded bytes (always equal to width * height) */
258 ret= av_get_packet(pb, pkt, chunk_size);
264 pal = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE,
268 memcpy(pal, palette, AVPALETTE_SIZE);
270 pkt->stream_index = idcin->video_stream_index;
271 pkt->pts = idcin->pts;
273 /* send out the audio chunk */
274 if (idcin->current_audio_chunk)
275 chunk_size = idcin->audio_chunk_size2;
277 chunk_size = idcin->audio_chunk_size1;
278 ret= av_get_packet(pb, pkt, chunk_size);
281 pkt->stream_index = idcin->audio_stream_index;
282 pkt->pts = idcin->pts;
284 idcin->current_audio_chunk ^= 1;
288 if (idcin->audio_present)
289 idcin->next_chunk_is_video ^= 1;
294 AVInputFormat ff_idcin_demuxer = {
296 .long_name = NULL_IF_CONFIG_SMALL("id Cinematic"),
297 .priv_data_size = sizeof(IdcinDemuxContext),
298 .read_probe = idcin_probe,
299 .read_header = idcin_read_header,
300 .read_packet = idcin_read_packet,