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
35 typedef struct MLPParseContext
36 {
37 ParseContext pc;
38
39 int bytes_left;
40
41 int in_sync;
42
43 int num_substreams;
44 } MLPParseContext;
45
mlp_init(AVCodecParserContext * s)46 static av_cold int mlp_init(AVCodecParserContext *s)
47 {
48 ff_mlp_init_crc();
49 return 0;
50 }
51
mlp_parse(AVCodecParserContext * s,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)52 static 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 if(!avctx->channels || !avctx->channel_layout) {
179 if (mh.stream_type == 0xbb) {
180 /* MLP stream */
181 avctx->channels = mh.channels_mlp;
182 avctx->channel_layout = mh.channel_layout_mlp;
183 } else { /* mh.stream_type == 0xba */
184 /* TrueHD stream */
185 if (!mh.channels_thd_stream2) {
186 avctx->channels = mh.channels_thd_stream1;
187 avctx->channel_layout = mh.channel_layout_thd_stream1;
188 } else {
189 avctx->channels = mh.channels_thd_stream2;
190 avctx->channel_layout = mh.channel_layout_thd_stream2;
191 }
192 }
193 }
194
195 if (!mh.is_vbr) /* Stream is CBR */
196 avctx->bit_rate = mh.peak_bitrate;
197
198 mp->num_substreams = mh.num_substreams;
199 }
200
201 *poutbuf = buf;
202 *poutbuf_size = buf_size;
203
204 return next;
205
206 lost_sync:
207 mp->in_sync = 0;
208 return 1;
209 }
210
211 AVCodecParser ff_mlp_parser = {
212 .codec_ids = { AV_CODEC_ID_MLP, AV_CODEC_ID_TRUEHD },
213 .priv_data_size = sizeof(MLPParseContext),
214 .parser_init = mlp_init,
215 .parser_parse = mlp_parse,
216 .parser_close = ff_parse_close,
217 };
218