libavformat/amr.c

   1 /*
   2  * amr file format
   3  * Copyright (c) 2001 ffmpeg project
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /*
  23 Write and read amr data according to RFC3267, http://www.ietf.org/rfc/rfc3267.txt?number=3267
  24
  25 Only mono files are supported.
  26
  27 */
  28
  29 #include "libavutil/channel_layout.h"
  30 #include "avformat.h"
  31 #include "internal.h"
  32
  33 static const char AMR_header[]   = "#!AMR\n";
  34 static const char AMRWB_header[] = "#!AMR-WB\n";
  35
  36 #if CONFIG_AMR_MUXER
  37 static int amr_write_header(AVFormatContext *s)
  38 {
  39     AVIOContext    *pb  = s->pb;
  40     AVCodecContext *enc = s->streams[0]->codec;
  41
  42     s->priv_data = NULL;
  43
  44     if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
  45         avio_write(pb, AMR_header,   sizeof(AMR_header)   - 1); /* magic number */
  46     } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
  47         avio_write(pb, AMRWB_header, sizeof(AMRWB_header) - 1); /* magic number */
  48     } else {
  49         return -1;
  50     }
  51     avio_flush(pb);
  52     return 0;
  53 }
  54
  55 static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)
  56 {
  57     avio_write(s->pb, pkt->data, pkt->size);
  58     avio_flush(s->pb);
  59     return 0;
  60 }
  61 #endif /* CONFIG_AMR_MUXER */
  62
  63 static int amr_probe(AVProbeData *p)
  64 {
  65     // Only check for "#!AMR" which could be amr-wb, amr-nb.
  66     // This will also trigger multichannel files: "#!AMR_MC1.0\n" and
  67     // "#!AMR-WB_MC1.0\n" (not supported)
  68
  69     if (!memcmp(p->buf, AMR_header, 5))
  70         return AVPROBE_SCORE_MAX;
  71     else
  72         return 0;
  73 }
  74
  75 /* amr input */
  76 static int amr_read_header(AVFormatContext *s)
  77 {
  78     AVIOContext *pb = s->pb;
  79     AVStream *st;
  80     uint8_t header[9];
  81
  82     avio_read(pb, header, 6);
  83
  84     st = avformat_new_stream(s, NULL);
  85     if (!st)
  86         return AVERROR(ENOMEM);
  87     if (memcmp(header, AMR_header, 6)) {
  88         avio_read(pb, header + 6, 3);
  89         if (memcmp(header, AMRWB_header, 9)) {
  90             return -1;
  91         }
  92
  93         st->codec->codec_tag   = MKTAG('s', 'a', 'w', 'b');
  94         st->codec->codec_id    = AV_CODEC_ID_AMR_WB;
  95         st->codec->sample_rate = 16000;
  96     } else {
  97         st->codec->codec_tag   = MKTAG('s', 'a', 'm', 'r');
  98         st->codec->codec_id    = AV_CODEC_ID_AMR_NB;
  99         st->codec->sample_rate = 8000;
 100     }
 101     st->codec->channels   = 1;
 102     st->codec->channel_layout = AV_CH_LAYOUT_MONO;
 103     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
 104     avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
 105
 106     return 0;
 107 }
 108
 109 static int amr_read_packet(AVFormatContext *s, AVPacket *pkt)
 110 {
 111     AVCodecContext *enc = s->streams[0]->codec;
 112     int read, size = 0, toc, mode;
 113     int64_t pos = avio_tell(s->pb);
 114
 115     if (s->pb->eof_reached) {
 116         return AVERROR(EIO);
 117     }
 118
 119     // FIXME this is wrong, this should rather be in a AVParset
 120     toc  = avio_r8(s->pb);
 121     mode = (toc >> 3) & 0x0F;
 122
 123     if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
 124         static const uint8_t packed_size[16] = {
 125             12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0
 126         };
 127
 128         size = packed_size[mode] + 1;
 129     } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
 130         static const uint8_t packed_size[16] = {
 131             18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1
 132         };
 133
 134         size = packed_size[mode];
 135     } else {
 136         assert(0);
 137     }
 138
 139     if (!size || av_new_packet(pkt, size))
 140         return AVERROR(EIO);
 141
 142     /* Both AMR formats have 50 frames per second */
 143     s->streams[0]->codec->bit_rate = size*8*50;
 144
 145     pkt->stream_index = 0;
 146     pkt->pos          = pos;
 147     pkt->data[0]      = toc;
 148     pkt->duration     = enc->codec_id == AV_CODEC_ID_AMR_NB ? 160 : 320;
 149     read              = avio_read(s->pb, pkt->data + 1, size - 1);
 150
 151     if (read != size - 1) {
 152         av_free_packet(pkt);
 153         return AVERROR(EIO);
 154     }
 155
 156     return 0;
 157 }
 158
 159 #if CONFIG_AMR_DEMUXER
 160 AVInputFormat ff_amr_demuxer = {
 161     .name           = "amr",
 162     .long_name      = NULL_IF_CONFIG_SMALL("3GPP AMR"),
 163     .read_probe     = amr_probe,
 164     .read_header    = amr_read_header,
 165     .read_packet    = amr_read_packet,
 166     .flags          = AVFMT_GENERIC_INDEX,
 167 };
 168 #endif
 169
 170 #if CONFIG_AMR_MUXER
 171 AVOutputFormat ff_amr_muxer = {
 172     .name              = "amr",
 173     .long_name         = NULL_IF_CONFIG_SMALL("3GPP AMR"),
 174     .mime_type         = "audio/amr",
 175     .extensions        = "amr",
 176     .audio_codec       = AV_CODEC_ID_AMR_NB,
 177     .video_codec       = AV_CODEC_ID_NONE,
 178     .write_header      = amr_write_header,
 179     .write_packet      = amr_write_packet,
 180 };
 181 #endif