summaryrefslogtreecommitdiff
path: root/libavcodec/mlp_parser.c
blob: 925ed86de29514dcdabe659f67285acdd45af973 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
/*
 * MLP parser
 * Copyright (c) 2007 Ian Caulfield
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file mlp_parser.c
 * MLP parser
 */

#include <stdint.h>

#include "libavutil/crc.h"
#include "bitstream.h"
#include "parser.h"
#include "mlp_parser.h"
#include "mlp.h"

static const uint8_t mlp_quants[16] = {
    16, 20, 24, 0, 0, 0, 0, 0,
     0,  0,  0, 0, 0, 0, 0, 0,
};

static const uint8_t mlp_channels[32] = {
    1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
    5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};

static const uint8_t thd_chancount[13] = {
//  LR    C   LFE  LRs LRvh  LRc LRrs  Cs   Ts  LRsd  LRw  Cvh  LFE2
     2,   1,   1,   2,   2,   2,   2,   1,   1,   2,   2,   1,   1
};

static int mlp_samplerate(int in)
{
    if (in == 0xF)
        return 0;

    return (in & 8 ? 44100 : 48000) << (in & 7) ;
}

static int truehd_channels(int chanmap)
{
    int channels = 0, i;

    for (i = 0; i < 13; i++)
        channels += thd_chancount[i] * ((chanmap >> i) & 1);

    return channels;
}

/** Read a major sync info header - contains high level information about
 *  the stream - sample rate, channel arrangement etc. Most of this
 *  information is not actually necessary for decoding, only for playback.
 *  gb must be a freshly initialized GetBitContext with no bits read.
 */

int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)
{
    int ratebits;
    uint16_t checksum;

    assert(get_bits_count(gb) == 0);

    if (gb->size_in_bits < 28 << 3) {
        av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
        return -1;
    }

    checksum = ff_mlp_checksum16(gb->buffer, 26);
    if (checksum != AV_RL16(gb->buffer+26)) {
        av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
        return -1;
    }

    if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */
        return -1;

    mh->stream_type = get_bits(gb, 8);

    if (mh->stream_type == 0xbb) {
        mh->group1_bits = mlp_quants[get_bits(gb, 4)];
        mh->group2_bits = mlp_quants[get_bits(gb, 4)];

        ratebits = get_bits(gb, 4);
        mh->group1_samplerate = mlp_samplerate(ratebits);
        mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));

        skip_bits(gb, 11);

        mh->channels_mlp = get_bits(gb, 5);
    } else if (mh->stream_type == 0xba) {
        mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
        mh->group2_bits = 0;

        ratebits = get_bits(gb, 4);
        mh->group1_samplerate = mlp_samplerate(ratebits);
        mh->group2_samplerate = 0;

        skip_bits(gb, 8);

        mh->channels_thd_stream1 = get_bits(gb, 5);

        skip_bits(gb, 2);

        mh->channels_thd_stream2 = get_bits(gb, 13);
    } else
        return -1;

    mh->access_unit_size = 40 << (ratebits & 7);
    mh->access_unit_size_pow2 = 64 << (ratebits & 7);

    skip_bits_long(gb, 48);

    mh->is_vbr = get_bits1(gb);

    mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;

    mh->num_substreams = get_bits(gb, 4);

    skip_bits_long(gb, 4 + 11 * 8);

    return 0;
}

typedef struct MLPParseContext
{
    ParseContext pc;

    int bytes_left;

    int in_sync;

    int num_substreams;
} MLPParseContext;

static av_cold int mlp_init(AVCodecParserContext *s)
{
    ff_mlp_init_crc();
    return 0;
}

static int mlp_parse(AVCodecParserContext *s,
                     AVCodecContext *avctx,
                     const uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size)
{
    MLPParseContext *mp = s->priv_data;
    int sync_present;
    uint8_t parity_bits;
    int next;
    int i, p = 0;

    *poutbuf_size = 0;
    if (buf_size == 0)
        return 0;

    if (!mp->in_sync) {
        // Not in sync - find a major sync header

        for (i = 0; i < buf_size; i++) {
            mp->pc.state = (mp->pc.state << 8) | buf[i];
            if ((mp->pc.state & 0xfffffffe) == 0xf8726fba) {
                mp->in_sync = 1;
                mp->bytes_left = 0;
                break;
            }
        }

        if (!mp->in_sync) {
            ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
            return buf_size;
        }

        ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);

        return i - 7;
    }

    if (mp->bytes_left == 0) {
        // Find length of this packet

        /* Copy overread bytes from last frame into buffer. */
        for(; mp->pc.overread>0; mp->pc.overread--) {
            mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
        }

        if (mp->pc.index + buf_size < 2) {
            ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
            return buf_size;
        }

        mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
                       |  (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
        mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
        mp->bytes_left -= mp->pc.index;
    }

    next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;

    if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
        mp->bytes_left -= buf_size;
        return buf_size;
    }

    mp->bytes_left = 0;

    sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;

    if (!sync_present) {
        /* The first nibble of a frame is a parity check of the 4-byte
         * access unit header and all the 2- or 4-byte substream headers. */
        // Only check when this isn't a sync frame - syncs have a checksum.

        parity_bits = 0;
        for (i = -1; i < mp->num_substreams; i++) {
            parity_bits ^= buf[p++];
            parity_bits ^= buf[p++];

            if (i < 0 || buf[p-2] & 0x80) {
                parity_bits ^= buf[p++];
                parity_bits ^= buf[p++];
            }
        }

        if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
            av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
            goto lost_sync;
        }
    } else {
        GetBitContext gb;
        MLPHeaderInfo mh;

        init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
        if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
            goto lost_sync;

        avctx->bits_per_raw_sample = mh.group1_bits;
        if (avctx->bits_per_raw_sample > 16)
            avctx->sample_fmt = SAMPLE_FMT_S32;
        else
            avctx->sample_fmt = SAMPLE_FMT_S16;
        avctx->sample_rate = mh.group1_samplerate;
        avctx->frame_size = mh.access_unit_size;

        if (mh.stream_type == 0xbb) {
            /* MLP stream */
            avctx->channels = mlp_channels[mh.channels_mlp];
        } else { /* mh.stream_type == 0xba */
            /* TrueHD stream */
            if (mh.channels_thd_stream2)
                avctx->channels = truehd_channels(mh.channels_thd_stream2);
            else
                avctx->channels = truehd_channels(mh.channels_thd_stream1);
        }

        if (!mh.is_vbr) /* Stream is CBR */
            avctx->bit_rate = mh.peak_bitrate;

        mp->num_substreams = mh.num_substreams;
    }

    *poutbuf = buf;
    *poutbuf_size = buf_size;

    return next;

lost_sync:
    mp->in_sync = 0;
    return 1;
}

AVCodecParser mlp_parser = {
    { CODEC_ID_MLP },
    sizeof(MLPParseContext),
    mlp_init,
    mlp_parse,
    NULL,
};