yading@11: /*
yading@11:  * PCM common functions
yading@11:  * Copyright (c) 2003 Fabrice Bellard
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "libavutil/mathematics.h"
yading@11: #include "avformat.h"
yading@11: #include "pcm.h"
yading@11: 
yading@11: #define RAW_SAMPLES     1024
yading@11: 
yading@11: int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
yading@11: {
yading@11:     int ret, size;
yading@11: 
yading@11:     size= RAW_SAMPLES*s->streams[0]->codec->block_align;
yading@11:     if (size <= 0)
yading@11:         return AVERROR(EINVAL);
yading@11: 
yading@11:     ret= av_get_packet(s->pb, pkt, size);
yading@11: 
yading@11:     pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
yading@11:     pkt->stream_index = 0;
yading@11:     if (ret < 0)
yading@11:         return ret;
yading@11: 
yading@11:     return ret;
yading@11: }
yading@11: 
yading@11: int ff_pcm_read_seek(AVFormatContext *s,
yading@11:                      int stream_index, int64_t timestamp, int flags)
yading@11: {
yading@11:     AVStream *st;
yading@11:     int block_align, byte_rate;
yading@11:     int64_t pos, ret;
yading@11: 
yading@11:     st = s->streams[0];
yading@11: 
yading@11:     block_align = st->codec->block_align ? st->codec->block_align :
yading@11:         (av_get_bits_per_sample(st->codec->codec_id) * st->codec->channels) >> 3;
yading@11:     byte_rate = st->codec->bit_rate ? st->codec->bit_rate >> 3 :
yading@11:         block_align * st->codec->sample_rate;
yading@11: 
yading@11:     if (block_align <= 0 || byte_rate <= 0)
yading@11:         return -1;
yading@11:     if (timestamp < 0) timestamp = 0;
yading@11: 
yading@11:     /* compute the position by aligning it to block_align */
yading@11:     pos = av_rescale_rnd(timestamp * byte_rate,
yading@11:                          st->time_base.num,
yading@11:                          st->time_base.den * (int64_t)block_align,
yading@11:                          (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
yading@11:     pos *= block_align;
yading@11: 
yading@11:     /* recompute exact position */
yading@11:     st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);
yading@11:     if ((ret = avio_seek(s->pb, pos + s->data_offset, SEEK_SET)) < 0)
yading@11:         return ret;
yading@11:     return 0;
yading@11: }