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
32static 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};
35static 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
39typedef 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
47static av_cold int amr_parse_init(AVCodecParserContext *s1)
48{
49    AMRParseContext *s = s1->priv_data;
50    s->remaining = -1;
51    return 0;
52}
53
54static 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
125const 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