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
  22 #include "config_components.h"
  23
  24 #include "avformat.h"
  25 #include "avio_internal.h"
  26 #include "demux.h"
  27 #include "internal.h"
  28 #include "mux.h"
  29 #include "libavcodec/get_bits.h"
  30 #include "libavcodec/put_bits.h"
  31
  32 #define MAX_FRAME_SIZE 10
  33
  34 #define SYNC_WORD  0x6b21
  35 #define BIT_0      0x7f
  36 #define BIT_1      0x81
  37
  38 #if CONFIG_BIT_DEMUXER
  39 static int probe(const AVProbeData *p)
  40 {
  41     int i = 0, j, valid = 0;
  42
  43     while (2 * i + 3 < p->buf_size){
  44         if (AV_RL16(&p->buf[2 * i++]) != SYNC_WORD)
  45             return 0;
  46         j = AV_RL16(&p->buf[2 * i++]);
  47         if (j != 0 && j != 0x10 && j != 0x40 && j != 0x50 && j != 0x76)
  48             return 0;
  49         if (j)
  50             valid++;
  51         i += j;
  52     }
  53     if (valid > 10)
  54         return AVPROBE_SCORE_MAX;
  55     if (valid > 2)
  56         return AVPROBE_SCORE_EXTENSION - 1;
  57     return 0;
  58 }
  59
  60 static int read_header(AVFormatContext *s)
  61 {
  62     AVStream* st;
  63
  64     st=avformat_new_stream(s, NULL);
  65     if (!st)
  66         return AVERROR(ENOMEM);
  67
  68     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
  69     st->codecpar->codec_id=AV_CODEC_ID_G729;
  70     st->codecpar->sample_rate=8000;
  71     st->codecpar->block_align = 16;
  72     st->codecpar->ch_layout.nb_channels = 1;
  73
  74     avpriv_set_pts_info(st, 64, 1, 100);
  75     return 0;
  76 }
  77
  78 static int read_packet(AVFormatContext *s,
  79                           AVPacket *pkt)
  80 {
  81     AVIOContext *pb = s->pb;
  82     PutBitContext pbo;
  83     uint16_t buf[8 * MAX_FRAME_SIZE + 2];
  84     int packet_size;
  85     uint16_t* src=buf;
  86     int i, j, ret;
  87     int64_t pos= avio_tell(pb);
  88
  89     if(avio_feof(pb))
  90         return AVERROR_EOF;
  91
  92     avio_rl16(pb); // sync word
  93     packet_size = avio_rl16(pb) / 8;
  94     if(packet_size > MAX_FRAME_SIZE)
  95         return AVERROR_INVALIDDATA;
  96
  97     ret = ffio_read_size(pb, (uint8_t*)buf, (8 * packet_size) * sizeof(uint16_t));
  98     if(ret<0)
  99         return ret;
 100
 101     if ((ret = av_new_packet(pkt, packet_size)) < 0)
 102         return ret;
 103
 104     init_put_bits(&pbo, pkt->data, packet_size);
 105     for(j=0; j < packet_size; j++)
 106         for(i=0; i<8;i++)
 107             put_bits(&pbo,1, AV_RL16(src++) == BIT_1 ? 1 : 0);
 108
 109     flush_put_bits(&pbo);
 110
 111     pkt->duration=1;
 112     pkt->pos = pos;
 113     return 0;
 114 }
 115
 116 const FFInputFormat ff_bit_demuxer = {
 117     .p.name       = "bit",
 118     .p.long_name  = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),
 119     .p.extensions = "bit",
 120     .read_probe  = probe,
 121     .read_header = read_header,
 122     .read_packet = read_packet,
 123 };
 124 #endif
 125
 126 #if CONFIG_BIT_MUXER
 127 static av_cold int init(AVFormatContext *s)
 128 {
 129     AVCodecParameters *par = s->streams[0]->codecpar;
 130
 131     if (par->ch_layout.nb_channels != 1) {
 132         av_log(s, AV_LOG_ERROR,
 133                "only codec g729 with 1 channel is supported by this format\n");
 134         return AVERROR(EINVAL);
 135     }
 136
 137     par->bits_per_coded_sample = 16;
 138     par->block_align = (par->bits_per_coded_sample * par->ch_layout.nb_channels) >> 3;
 139
 140     return 0;
 141 }
 142
 143 static int write_packet(AVFormatContext *s, AVPacket *pkt)
 144 {
 145     AVIOContext *pb = s->pb;
 146     GetBitContext gb;
 147     int i;
 148
 149     if (pkt->size != 10)
 150         return AVERROR(EINVAL);
 151
 152     avio_wl16(pb, SYNC_WORD);
 153     avio_wl16(pb, 8 * pkt->size);
 154
 155     init_get_bits(&gb, pkt->data, 8 * pkt->size);
 156     for (i = 0; i < 8 * pkt->size; i++)
 157         avio_wl16(pb, get_bits1(&gb) ? BIT_1 : BIT_0);
 158
 159     return 0;
 160 }
 161
 162 const FFOutputFormat ff_bit_muxer = {
 163     .p.name         = "bit",
 164     .p.long_name    = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),
 165     .p.mime_type    = "audio/bit",
 166     .p.extensions   = "bit",
 167     .p.audio_codec  = AV_CODEC_ID_G729,
 168     .p.video_codec  = AV_CODEC_ID_NONE,
 169     .p.subtitle_codec = AV_CODEC_ID_NONE,
 170     .flags_internal   = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
 171                         FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,
 172     .init             = init,
 173     .write_packet = write_packet,
 174 };
 175 #endif