summaryrefslogtreecommitdiffstats
path: root/libavformat/amr.c
blob: cc4842ebd556417ffe2d8e96c4271898a794419f (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
/*
 * amr file format
 * Copyright (c) 2001 ffmpeg project
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/*
Write and read amr data according to RFC3267, http://www.ietf.org/rfc/rfc3267.txt?number=3267

Only mono files are supported.

*/
#include "avformat.h"
#include "internal.h"

static const char AMR_header[]   = "#!AMR\n";
static const char AMRWB_header[] = "#!AMR-WB\n";

#if CONFIG_AMR_MUXER
static int amr_write_header(AVFormatContext *s)
{
    AVIOContext    *pb  = s->pb;
    AVCodecContext *enc = s->streams[0]->codec;

    s->priv_data = NULL;

    if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
        avio_write(pb, AMR_header,   sizeof(AMR_header)   - 1); /* magic number */
    } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
        avio_write(pb, AMRWB_header, sizeof(AMRWB_header) - 1); /* magic number */
    } else {
        return -1;
    }
    avio_flush(pb);
    return 0;
}

static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    avio_write(s->pb, pkt->data, pkt->size);
    avio_flush(s->pb);
    return 0;
}
#endif /* CONFIG_AMR_MUXER */

static int amr_probe(AVProbeData *p)
{
    // Only check for "#!AMR" which could be amr-wb, amr-nb.
    // This will also trigger multichannel files: "#!AMR_MC1.0\n" and
    // "#!AMR-WB_MC1.0\n" (not supported)

    if (!memcmp(p->buf, AMR_header, 5))
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

/* amr input */
static int amr_read_header(AVFormatContext *s)
{
    AVIOContext *pb = s->pb;
    AVStream *st;
    uint8_t header[9];

    avio_read(pb, header, 6);

    st = avformat_new_stream(s, NULL);
    if (!st)
        return AVERROR(ENOMEM);
    if (memcmp(header, AMR_header, 6)) {
        avio_read(pb, header + 6, 3);
        if (memcmp(header, AMRWB_header, 9)) {
            return -1;
        }

        st->codec->codec_tag   = MKTAG('s', 'a', 'w', 'b');
        st->codec->codec_id    = AV_CODEC_ID_AMR_WB;
        st->codec->sample_rate = 16000;
    } else {
        st->codec->codec_tag   = MKTAG('s', 'a', 'm', 'r');
        st->codec->codec_id    = AV_CODEC_ID_AMR_NB;
        st->codec->sample_rate = 8000;
    }
    st->codec->channels   = 1;
    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
    avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);

    return 0;
}

static int amr_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    AVCodecContext *enc = s->streams[0]->codec;
    int read, size = 0, toc, mode;
    int64_t pos = avio_tell(s->pb);

    if (s->pb->eof_reached) {
        return AVERROR(EIO);
    }

    // FIXME this is wrong, this should rather be in a AVParset
    toc  = avio_r8(s->pb);
    mode = (toc >> 3) & 0x0F;

    if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
        static const uint8_t packed_size[16] = {
            12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0
        };

        size = packed_size[mode] + 1;
    } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
        static const uint8_t packed_size[16] = {
            18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1
        };

        size = packed_size[mode];
    } else {
        assert(0);
    }

    if (!size || av_new_packet(pkt, size))
        return AVERROR(EIO);

    /* Both AMR formats have 50 frames per second */
    s->streams[0]->codec->bit_rate = size*8*50;

    pkt->stream_index = 0;
    pkt->pos          = pos;
    pkt->data[0]      = toc;
    pkt->duration     = enc->codec_id == AV_CODEC_ID_AMR_NB ? 160 : 320;
    read              = avio_read(s->pb, pkt->data + 1, size - 1);

    if (read != size - 1) {
        av_free_packet(pkt);
        return AVERROR(EIO);
    }

    return 0;
}

#if CONFIG_AMR_DEMUXER
AVInputFormat ff_amr_demuxer = {
    .name           = "amr",
    .long_name      = NULL_IF_CONFIG_SMALL("3GPP AMR"),
    .read_probe     = amr_probe,
    .read_header    = amr_read_header,
    .read_packet    = amr_read_packet,
    .flags          = AVFMT_GENERIC_INDEX,
};
#endif

#if CONFIG_AMR_MUXER
AVOutputFormat ff_amr_muxer = {
    .name              = "amr",
    .long_name         = NULL_IF_CONFIG_SMALL("3GPP AMR"),
    .mime_type         = "audio/amr",
    .extensions        = "amr",
    .audio_codec       = AV_CODEC_ID_AMR_NB,
    .video_codec       = AV_CODEC_ID_NONE,
    .write_header      = amr_write_header,
    .write_packet      = amr_write_packet,
};
#endif
OpenPOWER on IntegriCloud