libav/audio.c

   1 /*
   2  * Linux audio play and grab interface
   3  * Copyright (c) 2000, 2001 Gerard Lantau.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <linux/soundcard.h>
  23 #include <unistd.h>
  24 #include <fcntl.h>
  25 #include <sys/ioctl.h>
  26 #include <sys/mman.h>
  27 #include <errno.h>
  28 #include <sys/time.h>
  29
  30 #include "avformat.h"
  31
  32 const char *audio_device = "/dev/dsp";
  33
  34 typedef struct {
  35     int fd;
  36     int rate;
  37     int channels;
  38 } AudioData;
  39
  40 #define AUDIO_BLOCK_SIZE 4096
  41
  42 /* audio read support */
  43
  44 static int audio_read(URLContext *h, UINT8 *buf, int size)
  45 {
  46     AudioData *s = h->priv_data;
  47     int ret;
  48
  49     ret = read(s->fd, buf, size);
  50     if (ret < 0)
  51         return -errno;
  52     else
  53         return ret;
  54 }
  55
  56 static int audio_write(URLContext *h, UINT8 *buf, int size)
  57 {
  58     AudioData *s = h->priv_data;
  59     int ret;
  60
  61     ret = write(s->fd, buf, size);
  62     if (ret < 0)
  63         return -errno;
  64     else
  65         return ret;
  66 }
  67
  68 static int audio_get_format(URLContext *h, URLFormat *f)
  69 {
  70     AudioData *s = h->priv_data;
  71
  72     strcpy(f->format_name, "pcm");
  73     f->sample_rate = s->rate;
  74     f->channels = s->channels;
  75     return 0;
  76 }
  77
  78 /* URI syntax: 'audio:[rate[,channels]]'
  79    default: rate=44100, channels=2
  80  */
  81 static int audio_open(URLContext *h, const char *uri, int flags)
  82 {
  83     AudioData *s;
  84     const char *p;
  85     int freq, channels, audio_fd;
  86     int tmp, err;
  87
  88     h->is_streamed = 1;
  89     h->packet_size = AUDIO_BLOCK_SIZE;
  90
  91     s = malloc(sizeof(AudioData));
  92     if (!s)
  93         return -ENOMEM;
  94     h->priv_data = s;
  95
  96     /* extract parameters */
  97     p = uri;
  98     strstart(p, "audio:", &p);
  99     freq = strtol(p, (char **)&p, 0);
 100     if (freq <= 0)
 101         freq = 44100;
 102     if (*p == ',')
 103         p++;
 104     channels = strtol(p, (char **)&p, 0);
 105     if (channels <= 0)
 106             channels = 2;
 107     s->rate = freq;
 108     s->channels = channels;
 109
 110     /* open linux audio device */
 111     if (flags & URL_WRONLY)
 112         audio_fd = open(audio_device,O_WRONLY);
 113     else
 114         audio_fd = open(audio_device,O_RDONLY);
 115     if (audio_fd < 0) {
 116         perror(audio_device);
 117         return -EIO;
 118     }
 119
 120     /* non blocking mode */
 121     fcntl(audio_fd, F_SETFL, O_NONBLOCK);
 122
 123 #if 0
 124     tmp=(NB_FRAGMENTS << 16) | FRAGMENT_BITS;
 125     err=ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &tmp);
 126     if (err < 0) {
 127         perror("SNDCTL_DSP_SETFRAGMENT");
 128     }
 129 #endif
 130
 131     tmp=AFMT_S16_LE;
 132     err=ioctl(audio_fd,SNDCTL_DSP_SETFMT,&tmp);
 133     if (err < 0) {
 134         perror("SNDCTL_DSP_SETFMT");
 135         goto fail;
 136     }
 137
 138     tmp= (channels == 2);
 139     err=ioctl(audio_fd,SNDCTL_DSP_STEREO,&tmp);
 140     if (err < 0) {
 141         perror("SNDCTL_DSP_STEREO");
 142         goto fail;
 143     }
 144
 145     tmp = freq;
 146     err=ioctl(audio_fd, SNDCTL_DSP_SPEED, &tmp);
 147     if (err < 0) {
 148         perror("SNDCTL_DSP_SPEED");
 149         goto fail;
 150     }
 151
 152     s->rate = tmp;
 153     s->fd = audio_fd;
 154
 155     return 0;
 156  fail:
 157     close(audio_fd);
 158     free(s);
 159     return -EIO;
 160 }
 161
 162 static int audio_close(URLContext *h)
 163 {
 164     AudioData *s = h->priv_data;
 165
 166     close(s->fd);
 167     free(s);
 168     return 0;
 169 }
 170
 171 URLProtocol audio_protocol = {
 172     "audio",
 173     audio_open,
 174     audio_read,
 175     audio_write,
 176     NULL, /* seek */
 177     audio_close,
 178     audio_get_format,
 179 };