1/* 2 * PCM common functions 3 * Copyright (c) 2003 Fabrice Bellard 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 "libavutil/mathematics.h" 23#include "avformat.h" 24#include "pcm.h" 25 26#define RAW_SAMPLES 1024 27 28int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt) 29{ 30 int ret, size; 31 32 size= RAW_SAMPLES*s->streams[0]->codec->block_align; 33 if (size <= 0) 34 return AVERROR(EINVAL); 35 36 ret= av_get_packet(s->pb, pkt, size); 37 38 pkt->flags &= ~AV_PKT_FLAG_CORRUPT; 39 pkt->stream_index = 0; 40 41 return ret; 42} 43 44int ff_pcm_read_seek(AVFormatContext *s, 45 int stream_index, int64_t timestamp, int flags) 46{ 47 AVStream *st; 48 int block_align, byte_rate; 49 int64_t pos, ret; 50 51 st = s->streams[0]; 52 53 block_align = st->codec->block_align ? st->codec->block_align : 54 (av_get_bits_per_sample(st->codec->codec_id) * st->codec->channels) >> 3; 55 byte_rate = st->codec->bit_rate ? st->codec->bit_rate >> 3 : 56 block_align * st->codec->sample_rate; 57 58 if (block_align <= 0 || byte_rate <= 0) 59 return -1; 60 if (timestamp < 0) timestamp = 0; 61 62 /* compute the position by aligning it to block_align */ 63 pos = av_rescale_rnd(timestamp * byte_rate, 64 st->time_base.num, 65 st->time_base.den * (int64_t)block_align, 66 (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP); 67 pos *= block_align; 68 69 /* recompute exact position */ 70 st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num); 71 if ((ret = avio_seek(s->pb, pos + s->data_offset, SEEK_SET)) < 0) 72 return ret; 73 return 0; 74} 75