| /* |
| * RAW GSM demuxer |
| * Copyright (c) 2011 Justin Ruggles |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg 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. |
| * |
| * FFmpeg 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 FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavutil/channel_layout.h" |
| #include "libavutil/mathematics.h" |
| #include "libavutil/opt.h" |
| #include "avformat.h" |
| #include "internal.h" |
| |
| #define GSM_BLOCK_SIZE 33 |
| #define GSM_BLOCK_SAMPLES 160 |
| #define GSM_SAMPLE_RATE 8000 |
| |
| typedef struct GSMDemuxerContext { |
| AVClass *class; |
| int sample_rate; |
| } GSMDemuxerContext; |
| |
| static int gsm_probe(const AVProbeData *p) |
| { |
| int valid = 0, invalid = 0; |
| uint8_t *b = p->buf; |
| while (b < p->buf + p->buf_size - 32) { |
| if ((*b & 0xf0) == 0xd0) { |
| valid++; |
| } else { |
| invalid++; |
| } |
| b += 33; |
| } |
| if (valid >> 5 > invalid) |
| return AVPROBE_SCORE_EXTENSION + 1; |
| return 0; |
| } |
| |
| static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt) |
| { |
| int ret, size; |
| |
| size = GSM_BLOCK_SIZE; |
| |
| pkt->pos = avio_tell(s->pb); |
| pkt->stream_index = 0; |
| |
| ret = av_get_packet(s->pb, pkt, size); |
| if (ret < GSM_BLOCK_SIZE) { |
| return ret < 0 ? ret : AVERROR(EIO); |
| } |
| pkt->duration = 1; |
| pkt->pts = pkt->pos / GSM_BLOCK_SIZE; |
| |
| return 0; |
| } |
| |
| static int gsm_read_header(AVFormatContext *s) |
| { |
| GSMDemuxerContext *c = s->priv_data; |
| AVStream *st = avformat_new_stream(s, NULL); |
| if (!st) |
| return AVERROR(ENOMEM); |
| |
| st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO; |
| st->codecpar->codec_id = s->iformat->raw_codec_id; |
| st->codecpar->channels = 1; |
| st->codecpar->channel_layout = AV_CH_LAYOUT_MONO; |
| st->codecpar->sample_rate = c->sample_rate; |
| st->codecpar->bit_rate = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES; |
| |
| avpriv_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE); |
| |
| return 0; |
| } |
| |
| static const AVOption options[] = { |
| { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate), |
| AV_OPT_TYPE_INT, {.i64 = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE, |
| AV_OPT_FLAG_DECODING_PARAM }, |
| { NULL }, |
| }; |
| |
| static const AVClass gsm_class = { |
| .class_name = "gsm demuxer", |
| .item_name = av_default_item_name, |
| .option = options, |
| .version = LIBAVUTIL_VERSION_INT, |
| }; |
| |
| AVInputFormat ff_gsm_demuxer = { |
| .name = "gsm", |
| .long_name = NULL_IF_CONFIG_SMALL("raw GSM"), |
| .priv_data_size = sizeof(GSMDemuxerContext), |
| .read_probe = gsm_probe, |
| .read_header = gsm_read_header, |
| .read_packet = gsm_read_packet, |
| .flags = AVFMT_GENERIC_INDEX, |
| .extensions = "gsm", |
| .raw_codec_id = AV_CODEC_ID_GSM, |
| .priv_class = &gsm_class, |
| }; |