/*
  * PCM common functions
  * Copyright (c) 2003 Fabrice Bellard
  *
  * 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/mathematics.h"

 #include "avformat.h"

 #include "internal.h"

 #include "pcm.h"
 

 #define RAW_SAMPLES     1024
 
 int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
 {

     AVCodecParameters *par = s->streams[0]->codecpar;

     int ret, size;
 

     if (par->block_align <= 0)

         return AVERROR(EINVAL);

     /*
      * Compute read size to complete a read every 62ms.
      * Clamp to RAW_SAMPLES if larger.
      */
     size = FFMAX(par->sample_rate/25, 1);
     size = FFMIN(size, RAW_SAMPLES) * par->block_align;
 
     ret = av_get_packet(s->pb, pkt, size);

 
     pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
     pkt->stream_index = 0;
 
     return ret;
 }
 

 int ff_pcm_read_seek(AVFormatContext *s,
                      int stream_index, int64_t timestamp, int flags)

 {
     AVStream *st;
     int block_align, byte_rate;
     int64_t pos, ret;
 
     st = s->streams[0];
 

     block_align = st->codecpar->block_align ? st->codecpar->block_align :
         (av_get_bits_per_sample(st->codecpar->codec_id) * st->codecpar->channels) >> 3;
     byte_rate = st->codecpar->bit_rate ? st->codecpar->bit_rate >> 3 :
         block_align * st->codecpar->sample_rate;

 
     if (block_align <= 0 || byte_rate <= 0)
         return -1;
     if (timestamp < 0) timestamp = 0;
 
     /* compute the position by aligning it to block_align */
     pos = av_rescale_rnd(timestamp * byte_rate,
                          st->time_base.num,
                          st->time_base.den * (int64_t)block_align,
                          (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
     pos *= block_align;
 
     /* recompute exact position */
     st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);

     if ((ret = avio_seek(s->pb, pos + s->internal->data_offset, SEEK_SET)) < 0)

         return ret;
     return 0;
 }