Statistics
| Branch: | Revision:

ffmpeg / libavformat / rtpdec_amr.c @ 9dff2308

History | View | Annotate | Download (6.3 KB)

1
/*
2
 * RTP AMR Depacketizer, RFC 3267
3
 * Copyright (c) 2010 Martin Storsjo
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
#include "avformat.h"
23
#include "rtpdec_amr.h"
24
#include "libavutil/avstring.h"
25

    
26
static const uint8_t frame_sizes_nb[16] = {
27
    12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0
28
};
29
static const uint8_t frame_sizes_wb[16] = {
30
    17, 23, 32, 36, 40, 46, 50, 58, 60, 5, 5, 0, 0, 0, 0, 0
31
};
32

    
33
static int amr_handle_packet(AVFormatContext *ctx,
34
                             PayloadContext *data,
35
                             AVStream *st,
36
                             AVPacket * pkt,
37
                             uint32_t * timestamp,
38
                             const uint8_t * buf,
39
                             int len, int flags)
40
{
41
    const uint8_t *frame_sizes = NULL;
42
    int frames;
43
    int i;
44
    const uint8_t *speech_data;
45
    uint8_t *ptr;
46

    
47
    if (st->codec->codec_id == CODEC_ID_AMR_NB) {
48
        frame_sizes = frame_sizes_nb;
49
    } else if (st->codec->codec_id == CODEC_ID_AMR_WB) {
50
        frame_sizes = frame_sizes_wb;
51
    } else {
52
        av_log(ctx, AV_LOG_ERROR, "Bad codec ID\n");
53
        return AVERROR_INVALIDDATA;
54
    }
55

    
56
    if (st->codec->channels != 1) {
57
        av_log(ctx, AV_LOG_ERROR, "Only mono AMR is supported\n");
58
        return AVERROR_INVALIDDATA;
59
    }
60

    
61
    /* The AMR RTP packet consists of one header byte, followed
62
     * by one TOC byte for each AMR frame in the packet, followed
63
     * by the speech data for all the AMR frames.
64
     *
65
     * The header byte contains only a codec mode request, for
66
     * requesting what kind of AMR data the sender wants to
67
     * receive. Not used at the moment.
68
     */
69

    
70
    /* Count the number of frames in the packet. The highest bit
71
     * is set in a TOC byte if there are more frames following.
72
     */
73
    for (frames = 1; frames < len && (buf[frames] & 0x80); frames++) ;
74

    
75
    if (1 + frames >= len) {
76
        /* We hit the end of the packet while counting frames. */
77
        av_log(ctx, AV_LOG_ERROR, "No speech data found\n");
78
        return AVERROR_INVALIDDATA;
79
    }
80

    
81
    speech_data = buf + 1 + frames;
82

    
83
    /* Everything except the codec mode request byte should be output. */
84
    if (av_new_packet(pkt, len - 1)) {
85
        av_log(ctx, AV_LOG_ERROR, "Out of memory\n");
86
        return AVERROR_NOMEM;
87
    }
88
    pkt->stream_index = st->index;
89
    ptr = pkt->data;
90

    
91
    for (i = 0; i < frames; i++) {
92
        uint8_t toc = buf[1 + i];
93
        int frame_size = frame_sizes[(toc >> 3) & 0x0f];
94

    
95
        if (speech_data + frame_size > buf + len) {
96
            /* Too little speech data */
97
            av_log(ctx, AV_LOG_WARNING, "Too little speech data in the RTP packet\n");
98
            /* Set the unwritten part of the packet to zero. */
99
            memset(ptr, 0, pkt->data + pkt->size - ptr);
100
            pkt->size = ptr - pkt->data;
101
            return 0;
102
        }
103

    
104
        /* Extract the AMR frame mode from the TOC byte */
105
        *ptr++ = toc & 0x7C;
106

    
107
        /* Copy the speech data */
108
        memcpy(ptr, speech_data, frame_size);
109
        speech_data += frame_size;
110
        ptr += frame_size;
111
    }
112

    
113
    if (speech_data < buf + len) {
114
        av_log(ctx, AV_LOG_WARNING, "Too much speech data in the RTP packet?\n");
115
        /* Set the unwritten part of the packet to zero. */
116
        memset(ptr, 0, pkt->data + pkt->size - ptr);
117
        pkt->size = ptr - pkt->data;
118
    }
119

    
120
    return 0;
121
}
122

    
123
static int amr_parse_sdp_line(AVFormatContext *s, int st_index,
124
                              PayloadContext *data, const char *line)
125
{
126
    const char *p;
127
    char attr[25], value[25];
128

    
129
    /* Parse an fmtp line this one:
130
     * a=fmtp:97 octet-align=1; interleaving=0
131
     * That is, a normal fmtp: line followed by semicolon & space
132
     * separated key/value pairs.
133
     */
134
    if (av_strstart(line, "fmtp:", &p)) {
135
        int octet_align = 0;
136
        int crc = 0;
137
        int interleaving = 0;
138
        int channels = 1;
139

    
140
        while (*p && *p == ' ') p++; /* strip spaces */
141
        while (*p && *p != ' ') p++; /* eat protocol identifier */
142
        while (*p && *p == ' ') p++; /* strip trailing spaces */
143

    
144
        while (ff_rtsp_next_attr_and_value(&p, attr, sizeof(attr), value, sizeof(value))) {
145
            /* Some AMR SDP configurations contain "octet-align", without
146
             * the trailing =1. Therefore, if the value is empty,
147
             * interpret it as "1".
148
             */
149
            if (!strcmp(value, "")) {
150
                av_log(s, AV_LOG_WARNING, "AMR fmtp attribute %s had "
151
                                          "nonstandard empty value\n", attr);
152
                strcpy(value, "1");
153
            }
154
            if (!strcmp(attr, "octet-align"))
155
                octet_align = atoi(value);
156
            else if (!strcmp(attr, "crc"))
157
                crc = atoi(value);
158
            else if (!strcmp(attr, "interleaving"))
159
                interleaving = atoi(value);
160
            else if (!strcmp(attr, "channels"))
161
                channels = atoi(value);
162
        }
163
        if (!octet_align || crc || interleaving || channels != 1) {
164
            av_log(s, AV_LOG_ERROR, "Unsupported RTP/AMR configuration!\n");
165
            return -1;
166
        }
167
    }
168
    return 0;
169
}
170

    
171
RTPDynamicProtocolHandler ff_amr_nb_dynamic_handler = {
172
    .enc_name         = "AMR",
173
    .codec_type       = CODEC_TYPE_AUDIO,
174
    .codec_id         = CODEC_ID_AMR_NB,
175
    .parse_sdp_a_line = amr_parse_sdp_line,
176
    .parse_packet     = amr_handle_packet,
177
};
178

    
179
RTPDynamicProtocolHandler ff_amr_wb_dynamic_handler = {
180
    .enc_name         = "AMR-WB",
181
    .codec_type       = CODEC_TYPE_AUDIO,
182
    .codec_id         = CODEC_ID_AMR_WB,
183
    .parse_sdp_a_line = amr_parse_sdp_line,
184
    .parse_packet     = amr_handle_packet,
185
};
186