1/*
2 * MLP parser
3 * Copyright (c) 2007 Ian Caulfield
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 * MLP parser
25 */
26
27#include <stdint.h>
28
29#include "libavutil/internal.h"
30#include "get_bits.h"
31#include "parser.h"
32#include "mlp_parse.h"
33#include "mlp.h"
34
35typedef struct MLPParseContext
36{
37    ParseContext pc;
38
39    int bytes_left;
40
41    int in_sync;
42
43    int num_substreams;
44} MLPParseContext;
45
46static av_cold int mlp_init(AVCodecParserContext *s)
47{
48    ff_mlp_init_crc();
49    return 0;
50}
51
52static int mlp_parse(AVCodecParserContext *s,
53                     AVCodecContext *avctx,
54                     const uint8_t **poutbuf, int *poutbuf_size,
55                     const uint8_t *buf, int buf_size)
56{
57    MLPParseContext *mp = s->priv_data;
58    int sync_present;
59    uint8_t parity_bits;
60    int next;
61    int ret;
62    int i, p = 0;
63
64    s->key_frame = 0;
65
66    *poutbuf_size = 0;
67    *poutbuf = NULL;
68    if (buf_size == 0)
69        return 0;
70
71    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
72        next = buf_size;
73    } else {
74        if (!mp->in_sync) {
75            // Not in sync - find a major sync header
76
77            for (i = 0; i < buf_size; i++) {
78                mp->pc.state = (mp->pc.state << 8) | buf[i];
79                if ((mp->pc.state & 0xfffffffe) == 0xf8726fba &&
80                    // ignore if we do not have the data for the start of header
81                    mp->pc.index + i >= 7) {
82                    mp->in_sync = 1;
83                    mp->bytes_left = 0;
84                    break;
85                }
86            }
87
88            if (!mp->in_sync) {
89                if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)
90                    av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
91                return buf_size;
92            }
93
94            if ((ret = ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size)) < 0) {
95                av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
96                return ret;
97            }
98
99            return i - 7;
100        }
101
102        if (mp->bytes_left == 0) {
103            // Find length of this packet
104
105            /* Copy overread bytes from last frame into buffer. */
106            for(; mp->pc.overread>0; mp->pc.overread--) {
107                mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
108            }
109
110            if (mp->pc.index + buf_size < 2) {
111                if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)
112                    av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
113                return buf_size;
114            }
115
116            mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
117                           |  (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
118            mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
119            if (mp->bytes_left <= 0) { // prevent infinite loop
120                goto lost_sync;
121            }
122            mp->bytes_left -= mp->pc.index;
123        }
124
125        next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
126
127        if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
128            mp->bytes_left -= buf_size;
129            return buf_size;
130        }
131
132        mp->bytes_left = 0;
133    }
134
135    sync_present = buf_size >= 8 && (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
136
137    if (!sync_present) {
138        /* The first nibble of a frame is a parity check of the 4-byte
139         * access unit header and all the 2- or 4-byte substream headers. */
140        // Only check when this isn't a sync frame - syncs have a checksum.
141
142        s->key_frame = 0;
143
144        parity_bits = 0;
145        for (i = -1; i < mp->num_substreams; i++) {
146            parity_bits ^= buf[p++];
147            parity_bits ^= buf[p++];
148
149            if (i < 0 || buf[p-2] & 0x80) {
150                parity_bits ^= buf[p++];
151                parity_bits ^= buf[p++];
152            }
153        }
154
155        if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
156            av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
157            goto lost_sync;
158        }
159    } else {
160        GetBitContext gb;
161        MLPHeaderInfo mh;
162
163        init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
164        if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
165            goto lost_sync;
166
167        s->key_frame = 1;
168
169        avctx->bits_per_raw_sample = mh.group1_bits;
170        if (avctx->bits_per_raw_sample > 16)
171            avctx->sample_fmt = AV_SAMPLE_FMT_S32;
172        else
173            avctx->sample_fmt = AV_SAMPLE_FMT_S16;
174        avctx->sample_rate = mh.group1_samplerate;
175        avctx->frame_size =
176        s->duration = mh.access_unit_size;
177
178        av_channel_layout_uninit(&avctx->ch_layout);
179        if (mh.stream_type == 0xbb) {
180            /* MLP stream */
181            av_channel_layout_from_mask(&avctx->ch_layout, mh.channel_layout_mlp);
182        } else { /* mh.stream_type == 0xba */
183            /* TrueHD stream */
184            if (!mh.channels_thd_stream2) {
185                av_channel_layout_from_mask(&avctx->ch_layout, mh.channel_layout_thd_stream1);
186            } else {
187                av_channel_layout_from_mask(&avctx->ch_layout, mh.channel_layout_thd_stream2);
188            }
189        }
190
191        if (!mh.is_vbr) /* Stream is CBR */
192            avctx->bit_rate = mh.peak_bitrate;
193
194        mp->num_substreams = mh.num_substreams;
195    }
196
197    *poutbuf = buf;
198    *poutbuf_size = buf_size;
199
200    return next;
201
202lost_sync:
203    mp->in_sync = 0;
204    return 1;
205}
206
207const AVCodecParser ff_mlp_parser = {
208    .codec_ids      = { AV_CODEC_ID_MLP, AV_CODEC_ID_TRUEHD },
209    .priv_data_size = sizeof(MLPParseContext),
210    .parser_init    = mlp_init,
211    .parser_parse   = mlp_parse,
212    .parser_close   = ff_parse_close,
213};
214