/*
  * G.729 bit format muxer and demuxer
  * Copyright (c) 2007-2008 Vladimir Voroshilov
  *
  * 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 "avformat.h"

 #include "internal.h"

 #include "libavcodec/get_bits.h"
 #include "libavcodec/put_bits.h"
 
 #define MAX_FRAME_SIZE 10
 
 #define SYNC_WORD  0x6b21
 #define BIT_0      0x7f
 #define BIT_1      0x81
 
 static int probe(AVProbeData *p)
 {

     int i, j;
 

     if(p->buf_size < 0x40)
         return 0;
 

     for(i=0; i+3<p->buf_size && i< 10*0x50; ){
         if(AV_RL16(&p->buf[0]) != SYNC_WORD)
             return 0;
         j=AV_RL16(&p->buf[2]);
         if(j!=0x40 && j!=0x50)
             return 0;
         i+=j;

     }

     return AVPROBE_SCORE_MAX/2;

 }
 

 static int read_header(AVFormatContext *s)

 {
     AVStream* st;
 

     st=avformat_new_stream(s, NULL);

     if (!st)
         return AVERROR(ENOMEM);
 
     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

     st->codec->codec_id=AV_CODEC_ID_G729;

     st->codec->sample_rate=8000;
     st->codec->block_align = 16;
     st->codec->channels=1;
 

     avpriv_set_pts_info(st, 64, 1, 100);

     return 0;
 }
 
 static int read_packet(AVFormatContext *s,
                           AVPacket *pkt)
 {

     AVIOContext *pb = s->pb;

     PutBitContext pbo;
     uint16_t buf[8 * MAX_FRAME_SIZE + 2];
     int packet_size;
     uint16_t* src=buf;
     int i, j, ret;

     int64_t pos= avio_tell(pb);

 
     if(url_feof(pb))

         return AVERROR_EOF;

     avio_rl16(pb); // sync word
     packet_size = avio_rl16(pb) / 8;

     if(packet_size > MAX_FRAME_SIZE)

         return AVERROR_INVALIDDATA;

     ret = avio_read(pb, (uint8_t*)buf, (8 * packet_size) * sizeof(uint16_t));

     if(ret<0)
         return ret;
     if(ret != 8 * packet_size * sizeof(uint16_t))
         return AVERROR(EIO);
 

     if (av_new_packet(pkt, packet_size) < 0)
         return AVERROR(ENOMEM);

 
     init_put_bits(&pbo, pkt->data, packet_size);
     for(j=0; j < packet_size; j++)
         for(i=0; i<8;i++)
             put_bits(&pbo,1, AV_RL16(src++) == BIT_1 ? 1 : 0);
 
     flush_put_bits(&pbo);
 
     pkt->duration=1;

     pkt->pos = pos;

     return 0;
 }
 
 AVInputFormat ff_bit_demuxer = {

     .name        = "bit",
     .long_name   = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),
     .read_probe  = probe,
     .read_header = read_header,
     .read_packet = read_packet,
     .extensions  = "bit",

 };
 

 #if CONFIG_MUXERS

 static int write_header(AVFormatContext *s)
 {
     AVCodecContext *enc = s->streams[0]->codec;
 

     enc->codec_id = AV_CODEC_ID_G729;

     enc->channels = 1;
     enc->bits_per_coded_sample = 16;
     enc->block_align = (enc->bits_per_coded_sample * enc->channels) >> 3;
 
     return 0;
 }
 
 static int write_packet(AVFormatContext *s, AVPacket *pkt)
 {

     AVIOContext *pb = s->pb;

     GetBitContext gb;
     int i;
 

     avio_wl16(pb, SYNC_WORD);
     avio_wl16(pb, 8 * 10);

 
     init_get_bits(&gb, pkt->data, 8*10);
     for(i=0; i< 8 * 10; i++)

         avio_wl16(pb, get_bits1(&gb) ? BIT_1 : BIT_0);
     avio_flush(pb);

 
     return 0;
 }
 
 AVOutputFormat ff_bit_muxer = {

     .name         = "bit",
     .long_name    = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),
     .mime_type    = "audio/bit",
     .extensions   = "bit",

     .audio_codec  = AV_CODEC_ID_G729,
     .video_codec  = AV_CODEC_ID_NONE,

     .write_header = write_header,
     .write_packet = write_packet,

 };
 #endif