Statistics
| Branch: | Revision:

ffmpeg / libavformat / idcin.c @ b7effd4e

History | View | Annotate | Download (10.1 KB)

1
/*
2
 * id Quake II CIN File Demuxer
3
 * Copyright (c) 2003 The ffmpeg Project
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
/**
23
 * @file
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/
27
 *
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:
30
 *
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.
39
 *
40
 * Refer to the function idcin_probe() for the precise A/V parameters
41
 * that this demuxer allows.
42
 *
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
50
 * is given as:
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
55
 *
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
62
 * heuristic:
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
69
 */
70

    
71
#include "libavutil/intreadwrite.h"
72
#include "avformat.h"
73

    
74
#define HUFFMAN_TABLE_SIZE (64 * 1024)
75
#define IDCIN_FPS 14
76

    
77
typedef struct IdcinDemuxContext {
78
    int video_stream_index;
79
    int audio_stream_index;
80
    int audio_chunk_size1;
81
    int audio_chunk_size2;
82

    
83
    /* demux state variables */
84
    int current_audio_chunk;
85
    int next_chunk_is_video;
86
    int audio_present;
87

    
88
    int64_t pts;
89

    
90
    AVPaletteControl palctrl;
91
} IdcinDemuxContext;
92

    
93
static int idcin_probe(AVProbeData *p)
94
{
95
    unsigned int number;
96

    
97
    /*
98
     * This is what you could call a "probabilistic" file check: id CIN
99
     * files don't have a definite file signature. In lieu of such a marker,
100
     * perform sanity checks on the 5 32-bit header fields:
101
     *  width, height: greater than 0, less than or equal to 1024
102
     * audio sample rate: greater than or equal to 8000, less than or
103
     *  equal to 48000, or 0 for no audio
104
     * audio sample width (bytes/sample): 0 for no audio, or 1 or 2
105
     * audio channels: 0 for no audio, or 1 or 2
106
     */
107

    
108
    /* check we have enough data to do all checks, otherwise the
109
       0-padding may cause a wrong recognition */
110
    if (p->buf_size < 20)
111
        return 0;
112

    
113
    /* check the video width */
114
    number = AV_RL32(&p->buf[0]);
115
    if ((number == 0) || (number > 1024))
116
       return 0;
117

    
118
    /* check the video height */
119
    number = AV_RL32(&p->buf[4]);
120
    if ((number == 0) || (number > 1024))
121
       return 0;
122

    
123
    /* check the audio sample rate */
124
    number = AV_RL32(&p->buf[8]);
125
    if ((number != 0) && ((number < 8000) | (number > 48000)))
126
        return 0;
127

    
128
    /* check the audio bytes/sample */
129
    number = AV_RL32(&p->buf[12]);
130
    if (number > 2)
131
        return 0;
132

    
133
    /* check the audio channels */
134
    number = AV_RL32(&p->buf[16]);
135
    if (number > 2)
136
        return 0;
137

    
138
    /* return half certainly since this check is a bit sketchy */
139
    return AVPROBE_SCORE_MAX / 2;
140
}
141

    
142
static int idcin_read_header(AVFormatContext *s,
143
                             AVFormatParameters *ap)
144
{
145
    AVIOContext *pb = s->pb;
146
    IdcinDemuxContext *idcin = s->priv_data;
147
    AVStream *st;
148
    unsigned int width, height;
149
    unsigned int sample_rate, bytes_per_sample, channels;
150

    
151
    /* get the 5 header parameters */
152
    width = avio_rl32(pb);
153
    height = avio_rl32(pb);
154
    sample_rate = avio_rl32(pb);
155
    bytes_per_sample = avio_rl32(pb);
156
    channels = avio_rl32(pb);
157

    
158
    st = av_new_stream(s, 0);
159
    if (!st)
160
        return AVERROR(ENOMEM);
161
    av_set_pts_info(st, 33, 1, IDCIN_FPS);
162
    idcin->video_stream_index = st->index;
163
    st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
164
    st->codec->codec_id = CODEC_ID_IDCIN;
165
    st->codec->codec_tag = 0;  /* no fourcc */
166
    st->codec->width = width;
167
    st->codec->height = height;
168

    
169
    /* load up the Huffman tables into extradata */
170
    st->codec->extradata_size = HUFFMAN_TABLE_SIZE;
171
    st->codec->extradata = av_malloc(HUFFMAN_TABLE_SIZE);
172
    if (avio_read(pb, st->codec->extradata, HUFFMAN_TABLE_SIZE) !=
173
        HUFFMAN_TABLE_SIZE)
174
        return AVERROR(EIO);
175
    /* save a reference in order to transport the palette */
176
    st->codec->palctrl = &idcin->palctrl;
177

    
178
    /* if sample rate is 0, assume no audio */
179
    if (sample_rate) {
180
        idcin->audio_present = 1;
181
        st = av_new_stream(s, 0);
182
        if (!st)
183
            return AVERROR(ENOMEM);
184
        av_set_pts_info(st, 33, 1, IDCIN_FPS);
185
        idcin->audio_stream_index = st->index;
186
        st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
187
        st->codec->codec_tag = 1;
188
        st->codec->channels = channels;
189
        st->codec->sample_rate = sample_rate;
190
        st->codec->bits_per_coded_sample = bytes_per_sample * 8;
191
        st->codec->bit_rate = sample_rate * bytes_per_sample * 8 * channels;
192
        st->codec->block_align = bytes_per_sample * channels;
193
        if (bytes_per_sample == 1)
194
            st->codec->codec_id = CODEC_ID_PCM_U8;
195
        else
196
            st->codec->codec_id = CODEC_ID_PCM_S16LE;
197

    
198
        if (sample_rate % 14 != 0) {
199
            idcin->audio_chunk_size1 = (sample_rate / 14) *
200
            bytes_per_sample * channels;
201
            idcin->audio_chunk_size2 = (sample_rate / 14 + 1) *
202
                bytes_per_sample * channels;
203
        } else {
204
            idcin->audio_chunk_size1 = idcin->audio_chunk_size2 =
205
                (sample_rate / 14) * bytes_per_sample * channels;
206
        }
207
        idcin->current_audio_chunk = 0;
208
    } else
209
        idcin->audio_present = 1;
210

    
211
    idcin->next_chunk_is_video = 1;
212
    idcin->pts = 0;
213

    
214
    return 0;
215
}
216

    
217
static int idcin_read_packet(AVFormatContext *s,
218
                             AVPacket *pkt)
219
{
220
    int ret;
221
    unsigned int command;
222
    unsigned int chunk_size;
223
    IdcinDemuxContext *idcin = s->priv_data;
224
    AVIOContext *pb = s->pb;
225
    int i;
226
    int palette_scale;
227
    unsigned char r, g, b;
228
    unsigned char palette_buffer[768];
229

    
230
    if (url_feof(s->pb))
231
        return AVERROR(EIO);
232

    
233
    if (idcin->next_chunk_is_video) {
234
        command = avio_rl32(pb);
235
        if (command == 2) {
236
            return AVERROR(EIO);
237
        } else if (command == 1) {
238
            /* trigger a palette change */
239
            idcin->palctrl.palette_changed = 1;
240
            if (avio_read(pb, palette_buffer, 768) != 768)
241
                return AVERROR(EIO);
242
            /* scale the palette as necessary */
243
            palette_scale = 2;
244
            for (i = 0; i < 768; i++)
245
                if (palette_buffer[i] > 63) {
246
                    palette_scale = 0;
247
                    break;
248
                }
249

    
250
            for (i = 0; i < 256; i++) {
251
                r = palette_buffer[i * 3    ] << palette_scale;
252
                g = palette_buffer[i * 3 + 1] << palette_scale;
253
                b = palette_buffer[i * 3 + 2] << palette_scale;
254
                idcin->palctrl.palette[i] = (r << 16) | (g << 8) | (b);
255
            }
256
        }
257

    
258
        chunk_size = avio_rl32(pb);
259
        /* skip the number of decoded bytes (always equal to width * height) */
260
        url_fseek(pb, 4, SEEK_CUR);
261
        chunk_size -= 4;
262
        ret= av_get_packet(pb, pkt, chunk_size);
263
        if (ret < 0)
264
            return ret;
265
        pkt->stream_index = idcin->video_stream_index;
266
        pkt->pts = idcin->pts;
267
    } else {
268
        /* send out the audio chunk */
269
        if (idcin->current_audio_chunk)
270
            chunk_size = idcin->audio_chunk_size2;
271
        else
272
            chunk_size = idcin->audio_chunk_size1;
273
        ret= av_get_packet(pb, pkt, chunk_size);
274
        if (ret < 0)
275
            return ret;
276
        pkt->stream_index = idcin->audio_stream_index;
277
        pkt->pts = idcin->pts;
278

    
279
        idcin->current_audio_chunk ^= 1;
280
        idcin->pts++;
281
    }
282

    
283
    if (idcin->audio_present)
284
        idcin->next_chunk_is_video ^= 1;
285

    
286
    return ret;
287
}
288

    
289
AVInputFormat ff_idcin_demuxer = {
290
    "idcin",
291
    NULL_IF_CONFIG_SMALL("id Cinematic format"),
292
    sizeof(IdcinDemuxContext),
293
    idcin_probe,
294
    idcin_read_header,
295
    idcin_read_packet,
296
};