ffmpeg/libavdevice/oss_audio_dec.c

   1 /*
   2  * Linux audio play interface
   3  * Copyright (c) 2000, 2001 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 "config.h"
  23
  24 #include <stdint.h>
  25
  26 #if HAVE_SOUNDCARD_H
  27 #include <soundcard.h>
  28 #else
  29 #include <sys/soundcard.h>
  30 #endif
  31
  32 #if HAVE_UNISTD_H
  33 #include <unistd.h>
  34 #endif
  35 #include <fcntl.h>
  36 #include <sys/ioctl.h>
  37
  38 #include "libavutil/internal.h"
  39 #include "libavutil/opt.h"
  40 #include "libavutil/time.h"
  41
  42 #include "libavcodec/avcodec.h"
  43
  44 #include "avdevice.h"
  45 #include "libavformat/internal.h"
  46
  47 #include "oss_audio.h"
  48
  49 static int audio_read_header(AVFormatContext *s1)
  50 {
  51     OSSAudioData *s = s1->priv_data;
  52     AVStream *st;
  53     int ret;
  54
  55     st = avformat_new_stream(s1, NULL);
  56     if (!st) {
  57         return AVERROR(ENOMEM);
  58     }
  59
  60     ret = ff_oss_audio_open(s1, 0, s1->filename);
  61     if (ret < 0) {
  62         return AVERROR(EIO);
  63     }
  64
  65     /* take real parameters */
  66     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
  67     st->codec->codec_id = s->codec_id;
  68     st->codec->sample_rate = s->sample_rate;
  69     st->codec->channels = s->channels;
  70
  71     avpriv_set_pts_info(st, 64, 1, 1000000);  /* 64 bits pts in us */
  72     return 0;
  73 }
  74
  75 static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
  76 {
  77     OSSAudioData *s = s1->priv_data;
  78     int ret, bdelay;
  79     int64_t cur_time;
  80     struct audio_buf_info abufi;
  81
  82     if ((ret=av_new_packet(pkt, s->frame_size)) < 0)
  83         return ret;
  84
  85     ret = read(s->fd, pkt->data, pkt->size);
  86     if (ret <= 0){
  87         av_free_packet(pkt);
  88         pkt->size = 0;
  89         if (ret<0)  return AVERROR(errno);
  90         else        return AVERROR_EOF;
  91     }
  92     pkt->size = ret;
  93
  94     /* compute pts of the start of the packet */
  95     cur_time = av_gettime();
  96     bdelay = ret;
  97     if (ioctl(s->fd, SNDCTL_DSP_GETISPACE, &abufi) == 0) {
  98         bdelay += abufi.bytes;
  99     }
 100     /* subtract time represented by the number of bytes in the audio fifo */
 101     cur_time -= (bdelay * 1000000LL) / (s->sample_rate * s->channels);
 102
 103     /* convert to wanted units */
 104     pkt->pts = cur_time;
 105
 106     if (s->flip_left && s->channels == 2) {
 107         int i;
 108         short *p = (short *) pkt->data;
 109
 110         for (i = 0; i < ret; i += 4) {
 111             *p = ~*p;
 112             p += 2;
 113         }
 114     }
 115     return 0;
 116 }
 117
 118 static int audio_read_close(AVFormatContext *s1)
 119 {
 120     OSSAudioData *s = s1->priv_data;
 121
 122     ff_oss_audio_close(s);
 123     return 0;
 124 }
 125
 126 static const AVOption options[] = {
 127     { "sample_rate", "", offsetof(OSSAudioData, sample_rate), AV_OPT_TYPE_INT, {.i64 = 48000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
 128     { "channels",    "", offsetof(OSSAudioData, channels),    AV_OPT_TYPE_INT, {.i64 = 2},     1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
 129     { NULL },
 130 };
 131
 132 static const AVClass oss_demuxer_class = {
 133     .class_name     = "OSS demuxer",
 134     .item_name      = av_default_item_name,
 135     .option         = options,
 136     .version        = LIBAVUTIL_VERSION_INT,
 137     .category       = AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
 138 };
 139
 140 AVInputFormat ff_oss_demuxer = {
 141     .name           = "oss",
 142     .long_name      = NULL_IF_CONFIG_SMALL("OSS (Open Sound System) capture"),
 143     .priv_data_size = sizeof(OSSAudioData),
 144     .read_header    = audio_read_header,
 145     .read_packet    = audio_read_packet,
 146     .read_close     = audio_read_close,
 147     .flags          = AVFMT_NOFILE,
 148     .priv_class     = &oss_demuxer_class,
 149 };