1 /*
2 * Copyright (c) 2021 Paul B Mahol
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * AMR audio parser
24 *
25 * Splits packets into individual blocks.
26 */
27
28 #include "libavutil/channel_layout.h"
29 #include "libavutil/intreadwrite.h"
30 #include "parser.h"
31
32 static const uint8_t amrnb_packed_size[16] = {
33 13, 14, 16, 18, 20, 21, 27, 32, 6, 1, 1, 1, 1, 1, 1, 1
34 };
35 static const uint8_t amrwb_packed_size[16] = {
36 18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 1, 1, 1, 1, 1, 1
37 };
38
39 typedef struct AMRParseContext {
40 ParseContext pc;
41 uint64_t cumulated_size;
42 uint64_t block_count;
43 int current_channel;
44 int remaining;
45 } AMRParseContext;
46
amr_parse_init(AVCodecParserContext * s1)47 static av_cold int amr_parse_init(AVCodecParserContext *s1)
48 {
49 AMRParseContext *s = s1->priv_data;
50 s->remaining = -1;
51 return 0;
52 }
53
amr_parse(AVCodecParserContext * s1,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)54 static int amr_parse(AVCodecParserContext *s1,
55 AVCodecContext *avctx,
56 const uint8_t **poutbuf, int *poutbuf_size,
57 const uint8_t *buf, int buf_size)
58 {
59 AMRParseContext *s = s1->priv_data;
60 ParseContext *pc = &s->pc;
61 int next = END_NOT_FOUND;
62
63 *poutbuf_size = 0;
64 *poutbuf = NULL;
65
66 if (!avctx->ch_layout.nb_channels) {
67 av_channel_layout_uninit(&avctx->ch_layout);
68 avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
69 }
70
71 if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
72 next = buf_size;
73 } else {
74 int ch, offset = 0;
75
76 for (ch = s->current_channel; ch < avctx->ch_layout.nb_channels; ch++) {
77 if (s->remaining >= 0) {
78 next = s->remaining;
79 } else {
80 int mode = (buf[offset] >> 3) & 0x0F;
81
82 if (avctx->codec_id == AV_CODEC_ID_AMR_NB) {
83 next = amrnb_packed_size[mode];
84 } else if (avctx->codec_id == AV_CODEC_ID_AMR_WB) {
85 next = amrwb_packed_size[mode];
86 }
87 }
88
89 offset += next;
90 if (offset >= buf_size) {
91 s->remaining = offset - buf_size;
92 next = END_NOT_FOUND;
93 break;
94 } else {
95 s->remaining = -1;
96 }
97 }
98
99 s->current_channel = ch % avctx->ch_layout.nb_channels;
100 if (s->remaining < 0)
101 next = offset;
102
103 if (next != END_NOT_FOUND) {
104 if (s->cumulated_size < UINT64_MAX - next) {
105 s->cumulated_size += next;
106 /* Both AMR formats have 50 frames per second */
107 avctx->bit_rate = s->cumulated_size / ++s->block_count * 8 * 50;
108 }
109 }
110
111 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
112 *poutbuf = NULL;
113 *poutbuf_size = 0;
114 return buf_size;
115 }
116 }
117
118 s1->duration = avctx->codec_id == AV_CODEC_ID_AMR_NB ? 160 : 320;
119
120 *poutbuf = buf;
121 *poutbuf_size = buf_size;
122 return next;
123 }
124
125 const AVCodecParser ff_amr_parser = {
126 .codec_ids = { AV_CODEC_ID_AMR_NB, AV_CODEC_ID_AMR_WB },
127 .priv_data_size = sizeof(AMRParseContext),
128 .parser_init = amr_parse_init,
129 .parser_parse = amr_parse,
130 .parser_close = ff_parse_close,
131 };
132