2 * Id Quake II CIN File Demuxer
3 * Copyright (c) 2003 The ffmpeg Project
5 * This file is part of FFmpeg.
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.
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.
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
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
73 #define HUFFMAN_TABLE_SIZE (64 * 1024)
74 #define FRAME_PTS_INC (90000 / 14)
76 typedef struct IdcinDemuxContext {
77 int video_stream_index;
78 int audio_stream_index;
79 int audio_chunk_size1;
80 int audio_chunk_size2;
82 /* demux state variables */
83 int current_audio_chunk;
84 int next_chunk_is_video;
89 AVPaletteControl palctrl;
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 /* cannot proceed without 20 bytes */
108 if (p->buf_size < 20)
111 /* check the video width */
112 number = AV_RL32(&p->buf[0]);
113 if ((number == 0) || (number > 1024))
116 /* check the video height */
117 number = AV_RL32(&p->buf[4]);
118 if ((number == 0) || (number > 1024))
121 /* check the audio sample rate */
122 number = AV_RL32(&p->buf[8]);
123 if ((number != 0) && ((number < 8000) | (number > 48000)))
126 /* check the audio bytes/sample */
127 number = AV_RL32(&p->buf[12]);
131 /* check the audio channels */
132 number = AV_RL32(&p->buf[16]);
136 /* return half certainly since this check is a bit sketchy */
137 return AVPROBE_SCORE_MAX / 2;
140 static int idcin_read_header(AVFormatContext *s,
141 AVFormatParameters *ap)
143 ByteIOContext *pb = &s->pb;
144 IdcinDemuxContext *idcin = (IdcinDemuxContext *)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 = get_le32(pb);
151 height = get_le32(pb);
152 sample_rate = get_le32(pb);
153 bytes_per_sample = get_le32(pb);
154 channels = get_le32(pb);
156 st = av_new_stream(s, 0);
158 return AVERROR_NOMEM;
159 av_set_pts_info(st, 33, 1, 90000);
160 idcin->video_stream_index = st->index;
161 st->codec->codec_type = CODEC_TYPE_VIDEO;
162 st->codec->codec_id = 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 (get_buffer(pb, st->codec->extradata, HUFFMAN_TABLE_SIZE) !=
173 /* save a reference in order to transport the palette */
174 st->codec->palctrl = &idcin->palctrl;
176 /* if sample rate is 0, assume no audio */
178 idcin->audio_present = 1;
179 st = av_new_stream(s, 0);
181 return AVERROR_NOMEM;
182 av_set_pts_info(st, 33, 1, 90000);
183 idcin->audio_stream_index = st->index;
184 st->codec->codec_type = CODEC_TYPE_AUDIO;
185 st->codec->codec_tag = 1;
186 st->codec->channels = channels;
187 st->codec->sample_rate = sample_rate;
188 st->codec->bits_per_sample = bytes_per_sample * 8;
189 st->codec->bit_rate = sample_rate * bytes_per_sample * 8 * channels;
190 st->codec->block_align = bytes_per_sample * channels;
191 if (bytes_per_sample == 1)
192 st->codec->codec_id = CODEC_ID_PCM_U8;
194 st->codec->codec_id = CODEC_ID_PCM_S16LE;
196 if (sample_rate % 14 != 0) {
197 idcin->audio_chunk_size1 = (sample_rate / 14) *
198 bytes_per_sample * channels;
199 idcin->audio_chunk_size2 = (sample_rate / 14 + 1) *
200 bytes_per_sample * channels;
202 idcin->audio_chunk_size1 = idcin->audio_chunk_size2 =
203 (sample_rate / 14) * bytes_per_sample * channels;
205 idcin->current_audio_chunk = 0;
207 idcin->audio_present = 1;
209 idcin->next_chunk_is_video = 1;
215 static int idcin_read_packet(AVFormatContext *s,
219 unsigned int command;
220 unsigned int chunk_size;
221 IdcinDemuxContext *idcin = (IdcinDemuxContext *)s->priv_data;
222 ByteIOContext *pb = &s->pb;
225 unsigned char r, g, b;
226 unsigned char palette_buffer[768];
228 if (url_feof(&s->pb))
231 if (idcin->next_chunk_is_video) {
232 command = get_le32(pb);
235 } else if (command == 1) {
236 /* trigger a palette change */
237 idcin->palctrl.palette_changed = 1;
238 if (get_buffer(pb, palette_buffer, 768) != 768)
240 /* scale the palette as necessary */
242 for (i = 0; i < 768; i++)
243 if (palette_buffer[i] > 63) {
248 for (i = 0; i < 256; i++) {
249 r = palette_buffer[i * 3 ] << palette_scale;
250 g = palette_buffer[i * 3 + 1] << palette_scale;
251 b = palette_buffer[i * 3 + 2] << palette_scale;
252 idcin->palctrl.palette[i] = (r << 16) | (g << 8) | (b);
256 chunk_size = get_le32(pb);
257 /* skip the number of decoded bytes (always equal to width * height) */
258 url_fseek(pb, 4, SEEK_CUR);
260 ret= av_get_packet(pb, pkt, chunk_size);
261 if (ret != chunk_size)
263 pkt->stream_index = idcin->video_stream_index;
264 pkt->pts = idcin->pts;
266 /* send out the audio chunk */
267 if (idcin->current_audio_chunk)
268 chunk_size = idcin->audio_chunk_size2;
270 chunk_size = idcin->audio_chunk_size1;
271 ret= av_get_packet(pb, pkt, chunk_size);
272 if (ret != chunk_size)
274 pkt->stream_index = idcin->audio_stream_index;
275 pkt->pts = idcin->pts;
277 idcin->current_audio_chunk ^= 1;
278 idcin->pts += FRAME_PTS_INC;
281 if (idcin->audio_present)
282 idcin->next_chunk_is_video ^= 1;
287 static int idcin_read_close(AVFormatContext *s)
293 AVInputFormat idcin_demuxer = {
296 sizeof(IdcinDemuxContext),