libavformat/bit.c

   1 /*
   2  * G.729 bit format muxer and demuxer
   3  * Copyright (c) 2007-2008 Vladimir Voroshilov
   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 #include "avformat.h"
  22 #include "internal.h"
  23 #include "libavcodec/get_bits.h"
  24 #include "libavcodec/put_bits.h"
  25
  26 #define MAX_FRAME_SIZE 10
  27
  28 #define SYNC_WORD  0x6b21
  29 #define BIT_0      0x7f
  30 #define BIT_1      0x81
  31
  32 static int probe(AVProbeData *p)
  33 {
  34     int i, j;
  35
  36     if(p->buf_size < 0x40)
  37         return 0;
  38
  39     for(i=0; i+3<p->buf_size && i< 10*0x50; ){
  40         if(AV_RL16(&p->buf[0]) != SYNC_WORD)
  41             return 0;
  42         j=AV_RL16(&p->buf[2]);
  43         if(j!=0x40 && j!=0x50)
  44             return 0;
  45         i+=j;
  46     }
  47     return AVPROBE_SCORE_EXTENSION;
  48 }
  49
  50 static int read_header(AVFormatContext *s)
  51 {
  52     AVStream* st;
  53
  54     st=avformat_new_stream(s, NULL);
  55     if (!st)
  56         return AVERROR(ENOMEM);
  57
  58     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
  59     st->codecpar->codec_id=AV_CODEC_ID_G729;
  60     st->codecpar->sample_rate=8000;
  61     st->codecpar->block_align = 16;
  62     st->codecpar->channels=1;
  63
  64     avpriv_set_pts_info(st, 64, 1, 100);
  65     return 0;
  66 }
  67
  68 static int read_packet(AVFormatContext *s,
  69                           AVPacket *pkt)
  70 {
  71     AVIOContext *pb = s->pb;
  72     PutBitContext pbo;
  73     uint16_t buf[8 * MAX_FRAME_SIZE + 2];
  74     int packet_size;
  75     uint16_t* src=buf;
  76     int i, j, ret;
  77     int64_t pos= avio_tell(pb);
  78
  79     if(avio_feof(pb))
  80         return AVERROR_EOF;
  81
  82     avio_rl16(pb); // sync word
  83     packet_size = avio_rl16(pb) / 8;
  84     if(packet_size > MAX_FRAME_SIZE)
  85         return AVERROR_INVALIDDATA;
  86
  87     ret = avio_read(pb, (uint8_t*)buf, (8 * packet_size) * sizeof(uint16_t));
  88     if(ret<0)
  89         return ret;
  90     if(ret != 8 * packet_size * sizeof(uint16_t))
  91         return AVERROR(EIO);
  92
  93     if (av_new_packet(pkt, packet_size) < 0)
  94         return AVERROR(ENOMEM);
  95
  96     init_put_bits(&pbo, pkt->data, packet_size);
  97     for(j=0; j < packet_size; j++)
  98         for(i=0; i<8;i++)
  99             put_bits(&pbo,1, AV_RL16(src++) == BIT_1 ? 1 : 0);
 100
 101     flush_put_bits(&pbo);
 102
 103     pkt->duration=1;
 104     pkt->pos = pos;
 105     return 0;
 106 }
 107
 108 AVInputFormat ff_bit_demuxer = {
 109     .name        = "bit",
 110     .long_name   = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),
 111     .read_probe  = probe,
 112     .read_header = read_header,
 113     .read_packet = read_packet,
 114     .extensions  = "bit",
 115 };
 116
 117 #if CONFIG_MUXERS
 118 static int write_header(AVFormatContext *s)
 119 {
 120     AVCodecParameters *par = s->streams[0]->codecpar;
 121
 122     if ((par->codec_id != AV_CODEC_ID_G729) || par->channels != 1) {
 123         av_log(s, AV_LOG_ERROR,
 124                "only codec g729 with 1 channel is supported by this format\n");
 125         return AVERROR(EINVAL);
 126     }
 127
 128     par->bits_per_coded_sample = 16;
 129     par->block_align = (par->bits_per_coded_sample * par->channels) >> 3;
 130
 131     return 0;
 132 }
 133
 134 static int write_packet(AVFormatContext *s, AVPacket *pkt)
 135 {
 136     AVIOContext *pb = s->pb;
 137     GetBitContext gb;
 138     int i;
 139
 140     if (pkt->size != 10)
 141         return AVERROR(EINVAL);
 142
 143     avio_wl16(pb, SYNC_WORD);
 144     avio_wl16(pb, 8 * 10);
 145
 146     init_get_bits(&gb, pkt->data, 8*10);
 147     for(i=0; i< 8 * 10; i++)
 148         avio_wl16(pb, get_bits1(&gb) ? BIT_1 : BIT_0);
 149
 150     return 0;
 151 }
 152
 153 AVOutputFormat ff_bit_muxer = {
 154     .name         = "bit",
 155     .long_name    = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),
 156     .mime_type    = "audio/bit",
 157     .extensions   = "bit",
 158     .audio_codec  = AV_CODEC_ID_G729,
 159     .video_codec  = AV_CODEC_ID_NONE,
 160     .write_header = write_header,
 161     .write_packet = write_packet,
 162 };
 163 #endif