libav/audio.c

   1 /*
   2  * Linux audio play and grab interface
   3  * Copyright (c) 2000, 2001 Fabrice Bellard.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library 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 GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19 #include "avformat.h"
  20
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <sys/soundcard.h>
  25 #include <unistd.h>
  26 #include <fcntl.h>
  27 #include <sys/ioctl.h>
  28 #include <sys/mman.h>
  29 #include <sys/time.h>
  30
  31 const char *audio_device = "/dev/dsp";
  32
  33 #define AUDIO_BLOCK_SIZE 4096
  34
  35 typedef struct {
  36     int fd;
  37     int sample_rate;
  38     int channels;
  39     int frame_size; /* in bytes ! */
  40     int codec_id;
  41     int flip_left : 1;
  42     UINT8 buffer[AUDIO_BLOCK_SIZE];
  43     int buffer_ptr;
  44 } AudioData;
  45
  46 static int audio_open(AudioData *s, int is_output)
  47 {
  48     int audio_fd;
  49     int tmp, err;
  50     char *flip = getenv("AUDIO_FLIP_LEFT");
  51
  52     /* open linux audio device */
  53     if (is_output)
  54         audio_fd = open(audio_device, O_WRONLY);
  55     else
  56         audio_fd = open(audio_device, O_RDONLY);
  57     if (audio_fd < 0) {
  58         perror(audio_device);
  59         return -EIO;
  60     }
  61
  62     if (flip && *flip == '1') {
  63         s->flip_left = 1;
  64     }
  65
  66     /* non blocking mode */
  67     fcntl(audio_fd, F_SETFL, O_NONBLOCK);
  68
  69     s->frame_size = AUDIO_BLOCK_SIZE;
  70 #if 0
  71     tmp = (NB_FRAGMENTS << 16) | FRAGMENT_BITS;
  72     err = ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &tmp);
  73     if (err < 0) {
  74         perror("SNDCTL_DSP_SETFRAGMENT");
  75     }
  76 #endif
  77
  78     /* select format : favour native format */
  79     err = ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &tmp);
  80
  81 #ifdef WORDS_BIGENDIAN
  82     if (tmp & AFMT_S16_BE) {
  83         tmp = AFMT_S16_BE;
  84     } else if (tmp & AFMT_S16_LE) {
  85         tmp = AFMT_S16_LE;
  86     } else {
  87         tmp = 0;
  88     }
  89 #else
  90     if (tmp & AFMT_S16_LE) {
  91         tmp = AFMT_S16_LE;
  92     } else if (tmp & AFMT_S16_BE) {
  93         tmp = AFMT_S16_BE;
  94     } else {
  95         tmp = 0;
  96     }
  97 #endif
  98
  99     switch(tmp) {
 100     case AFMT_S16_LE:
 101         s->codec_id = CODEC_ID_PCM_S16LE;
 102         break;
 103     case AFMT_S16_BE:
 104         s->codec_id = CODEC_ID_PCM_S16BE;
 105         break;
 106     default:
 107         fprintf(stderr, "Soundcard does not support 16 bit sample format\n");
 108         close(audio_fd);
 109         return -EIO;
 110     }
 111     err=ioctl(audio_fd, SNDCTL_DSP_SETFMT, &tmp);
 112     if (err < 0) {
 113         perror("SNDCTL_DSP_SETFMT");
 114         goto fail;
 115     }
 116
 117     tmp = (s->channels == 2);
 118     err = ioctl(audio_fd, SNDCTL_DSP_STEREO, &tmp);
 119     if (err < 0) {
 120         perror("SNDCTL_DSP_STEREO");
 121         goto fail;
 122     }
 123     if (tmp)
 124         s->channels = 2;
 125
 126     tmp = s->sample_rate;
 127     err = ioctl(audio_fd, SNDCTL_DSP_SPEED, &tmp);
 128     if (err < 0) {
 129         perror("SNDCTL_DSP_SPEED");
 130         goto fail;
 131     }
 132     s->sample_rate = tmp; /* store real sample rate */
 133     s->fd = audio_fd;
 134
 135     return 0;
 136  fail:
 137     close(audio_fd);
 138     return -EIO;
 139 }
 140
 141 static int audio_close(AudioData *s)
 142 {
 143     close(s->fd);
 144     return 0;
 145 }
 146
 147 /* sound output support */
 148 static int audio_write_header(AVFormatContext *s1)
 149 {
 150     AudioData *s = s1->priv_data;
 151     AVStream *st;
 152     int ret;
 153
 154     st = s1->streams[0];
 155     s->sample_rate = st->codec.sample_rate;
 156     s->channels = st->codec.channels;
 157     ret = audio_open(s, 1);
 158     if (ret < 0) {
 159         return -EIO;
 160     } else {
 161         return 0;
 162     }
 163 }
 164
 165 static int audio_write_packet(AVFormatContext *s1, int stream_index,
 166                               UINT8 *buf, int size, int force_pts)
 167 {
 168     AudioData *s = s1->priv_data;
 169     int len, ret;
 170
 171     while (size > 0) {
 172         len = AUDIO_BLOCK_SIZE - s->buffer_ptr;
 173         if (len > size)
 174             len = size;
 175         memcpy(s->buffer + s->buffer_ptr, buf, len);
 176         s->buffer_ptr += len;
 177         if (s->buffer_ptr >= AUDIO_BLOCK_SIZE) {
 178             for(;;) {
 179                 ret = write(s->fd, s->buffer, AUDIO_BLOCK_SIZE);
 180                 if (ret != 0)
 181                     break;
 182                 if (ret < 0 && (errno != EAGAIN && errno != EINTR))
 183                     return -EIO;
 184             }
 185             s->buffer_ptr = 0;
 186         }
 187         buf += len;
 188         size -= len;
 189     }
 190     return 0;
 191 }
 192
 193 static int audio_write_trailer(AVFormatContext *s1)
 194 {
 195     AudioData *s = s1->priv_data;
 196
 197     audio_close(s);
 198     return 0;
 199 }
 200
 201 /* grab support */
 202
 203 static int audio_read_header(AVFormatContext *s1, AVFormatParameters *ap)
 204 {
 205     AudioData *s = s1->priv_data;
 206     AVStream *st;
 207     int ret;
 208
 209     if (!ap || ap->sample_rate <= 0 || ap->channels <= 0)
 210         return -1;
 211
 212     st = av_new_stream(s1, 0);
 213     if (!st) {
 214         return -ENOMEM;
 215     }
 216     s->sample_rate = ap->sample_rate;
 217     s->channels = ap->channels;
 218
 219     ret = audio_open(s, 0);
 220     if (ret < 0) {
 221         av_free(st);
 222         return -EIO;
 223     } else {
 224         /* take real parameters */
 225         st->codec.codec_type = CODEC_TYPE_AUDIO;
 226         st->codec.codec_id = s->codec_id;
 227         st->codec.sample_rate = s->sample_rate;
 228         st->codec.channels = s->channels;
 229         return 0;
 230     }
 231 }
 232
 233 static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
 234 {
 235     AudioData *s = s1->priv_data;
 236     int ret;
 237
 238     if (av_new_packet(pkt, s->frame_size) < 0)
 239         return -EIO;
 240     for(;;) {
 241         ret = read(s->fd, pkt->data, pkt->size);
 242         if (ret > 0)
 243             break;
 244         if (ret == -1 && (errno == EAGAIN || errno == EINTR)) {
 245             av_free_packet(pkt);
 246             pkt->size = 0;
 247             return 0;
 248         }
 249         if (!(ret == 0 || (ret == -1 && (errno == EAGAIN || errno == EINTR)))) {
 250             av_free_packet(pkt);
 251             return -EIO;
 252         }
 253     }
 254     pkt->size = ret;
 255     if (s->flip_left && s->channels == 2) {
 256         int i;
 257         short *p = (short *) pkt->data;
 258
 259         for (i = 0; i < ret; i += 4) {
 260             *p = ~*p;
 261             p += 2;
 262         }
 263     }
 264     return 0;
 265 }
 266
 267 static int audio_read_close(AVFormatContext *s1)
 268 {
 269     AudioData *s = s1->priv_data;
 270
 271     audio_close(s);
 272     return 0;
 273 }
 274
 275 AVInputFormat audio_in_format = {
 276     "audio_device",
 277     "audio grab and output",
 278     sizeof(AudioData),
 279     NULL,
 280     audio_read_header,
 281     audio_read_packet,
 282     audio_read_close,
 283     flags: AVFMT_NOFILE,
 284 };
 285
 286 AVOutputFormat audio_out_format = {
 287     "audio_device",
 288     "audio grab and output",
 289     "",
 290     "",
 291     sizeof(AudioData),
 292     /* XXX: we make the assumption that the soundcard accepts this format */
 293     /* XXX: find better solution with "preinit" method, needed also in
 294        other formats */
 295 #ifdef WORDS_BIGENDIAN
 296     CODEC_ID_PCM_S16BE,
 297 #else
 298     CODEC_ID_PCM_S16LE,
 299 #endif
 300     CODEC_ID_NONE,
 301     audio_write_header,
 302     audio_write_packet,
 303     audio_write_trailer,
 304     flags: AVFMT_NOFILE,
 305 };
 306
 307 int audio_init(void)
 308 {
 309     av_register_input_format(&audio_in_format);
 310     av_register_output_format(&audio_out_format);
 311     return 0;
 312 }