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1 | /* |
2 | * RAW GSM demuxer | |
3 | * Copyright (c) 2011 Justin Ruggles | |
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 "libavutil/channel_layout.h" | |
23 | #include "libavutil/mathematics.h" | |
24 | #include "libavutil/opt.h" | |
25 | #include "avformat.h" | |
26 | #include "internal.h" | |
27 | ||
28 | #define GSM_BLOCK_SIZE 33 | |
29 | #define GSM_BLOCK_SAMPLES 160 | |
30 | #define GSM_SAMPLE_RATE 8000 | |
31 | ||
32 | typedef struct { | |
33 | AVClass *class; | |
34 | int sample_rate; | |
35 | } GSMDemuxerContext; | |
36 | ||
37 | static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt) | |
38 | { | |
39 | int ret, size; | |
40 | ||
41 | size = GSM_BLOCK_SIZE; | |
42 | ||
43 | pkt->pos = avio_tell(s->pb); | |
44 | pkt->stream_index = 0; | |
45 | ||
46 | ret = av_get_packet(s->pb, pkt, size); | |
47 | if (ret < GSM_BLOCK_SIZE) { | |
48 | av_free_packet(pkt); | |
49 | return ret < 0 ? ret : AVERROR(EIO); | |
50 | } | |
51 | pkt->duration = 1; | |
52 | pkt->pts = pkt->pos / GSM_BLOCK_SIZE; | |
53 | ||
54 | return 0; | |
55 | } | |
56 | ||
57 | static int gsm_read_header(AVFormatContext *s) | |
58 | { | |
59 | GSMDemuxerContext *c = s->priv_data; | |
60 | AVStream *st = avformat_new_stream(s, NULL); | |
61 | if (!st) | |
62 | return AVERROR(ENOMEM); | |
63 | ||
64 | st->codec->codec_type = AVMEDIA_TYPE_AUDIO; | |
65 | st->codec->codec_id = s->iformat->raw_codec_id; | |
66 | st->codec->channels = 1; | |
67 | st->codec->channel_layout = AV_CH_LAYOUT_MONO; | |
68 | st->codec->sample_rate = c->sample_rate; | |
69 | st->codec->bit_rate = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES; | |
70 | ||
71 | avpriv_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE); | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
76 | static const AVOption options[] = { | |
77 | { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate), | |
78 | AV_OPT_TYPE_INT, {.i64 = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE, | |
79 | AV_OPT_FLAG_DECODING_PARAM }, | |
80 | { NULL }, | |
81 | }; | |
82 | ||
83 | static const AVClass gsm_class = { | |
84 | .class_name = "gsm demuxer", | |
85 | .item_name = av_default_item_name, | |
86 | .option = options, | |
87 | .version = LIBAVUTIL_VERSION_INT, | |
88 | }; | |
89 | ||
90 | AVInputFormat ff_gsm_demuxer = { | |
91 | .name = "gsm", | |
92 | .long_name = NULL_IF_CONFIG_SMALL("raw GSM"), | |
93 | .priv_data_size = sizeof(GSMDemuxerContext), | |
94 | .read_header = gsm_read_header, | |
95 | .read_packet = gsm_read_packet, | |
96 | .flags = AVFMT_GENERIC_INDEX, | |
97 | .extensions = "gsm", | |
98 | .raw_codec_id = AV_CODEC_ID_GSM, | |
99 | .priv_class = &gsm_class, | |
100 | }; |