oss_write.c

   1 /*
   2  * Copyright (C) 2009 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file oss_write.c Paraslash's oss output plugin. */
   8
   9 #include <regex.h>
  10 #include <sys/ioctl.h>
  11 #include <fcntl.h>
  12 #include <dirent.h>
  13 #include <sys/soundcard.h>
  14 #include <stdbool.h>
  15
  16 #include "para.h"
  17 #include "fd.h"
  18 #include "string.h"
  19 #include "list.h"
  20 #include "sched.h"
  21 #include "ggo.h"
  22 #include "buffer_tree.h"
  23 #include "write.h"
  24 #include "oss_write.cmdline.h"
  25 #include "error.h"
  26
  27 /** Always use 16 bit little endian. */
  28 #define FORMAT AFMT_S16_LE
  29
  30 /** Data specific to the oss writer. */
  31 struct private_oss_write_data {
  32         /** The file handle of the device. */
  33         int fd;
  34         /**
  35          * The samplerate given by command line option or the decoder
  36          * of the writer node group.
  37          */
  38         int samplerate;
  39         /**
  40          * The number of channels, given by command line option or the
  41          * decoder of the writer node group.
  42          */
  43         int channels;
  44         /** Four bytes for stereo streams, two bytes for mono streams. */
  45         int bytes_per_frame;
  46 };
  47
  48 static int oss_pre_select(struct sched *s, struct writer_node *wn)
  49 {
  50         struct private_oss_write_data *powd = wn->private_data;
  51         struct writer_node_group *wng = wn->wng;
  52
  53         if (*wng->loaded - wn->written < powd->bytes_per_frame)
  54                 return 0;
  55         para_fd_set(powd->fd, &s->wfds, &s->max_fileno);
  56         return 1;
  57 }
  58
  59 static int oss_post_select(struct sched *s, struct writer_node *wn)
  60 {
  61         int ret;
  62         struct private_oss_write_data *powd = wn->private_data;
  63         struct writer_node_group *wng = wn->wng;
  64         size_t frames, bytes = *wng->loaded - wn->written;
  65         char *data = *wng->bufp + wn->written;
  66
  67         if (*wng->input_error < 0 && bytes < powd->bytes_per_frame) {
  68                 wn->written = *wng->loaded;
  69                 return *wng->input_error;
  70         }
  71         frames = bytes / powd->bytes_per_frame;
  72         if (!frames) /* less than a single frame available */
  73                 goto out;
  74         if (!FD_ISSET(powd->fd, &s->wfds))
  75                 goto out;
  76         ret = write_nonblock(powd->fd, data, frames * powd->bytes_per_frame, 0);
  77         if (ret < 0)
  78                 return ret;
  79         wn->written += ret;
  80 out:
  81         return 1;
  82 }
  83
  84 static void oss_close(struct writer_node *wn)
  85 {
  86         struct private_oss_write_data *powd = wn->private_data;
  87
  88         close(powd->fd);
  89         free(powd);
  90 }
  91
  92 /*
  93  * The Open Sound System Programmer's Guide sayeth:
  94  *
  95  * Set sampling parameters always so that number of channels (mono/stereo) is
  96  * set before selecting sampling rate (speed).  Failing to do this will make
  97  * your program incompatible with cards such as the SoundBlaster Pro which
  98  * supports 44.1 kHz in mono but just 22.05 kHz in stereo. A program which
  99  * selects 44.1 kHz speed and then sets the device to stereo mode will
 100  * incorrectly believe that the device is still in 44.1 kHz mode when actually
 101  * the speed is decreased to 22.05 kHz.
 102  */
 103 static int oss_open(struct writer_node *wn)
 104 {
 105         int ret, format = FORMAT, channels, samplerate;
 106         struct oss_write_args_info *conf = wn->conf;
 107         struct writer_node_group *wng = wn->wng;
 108         struct private_oss_write_data *powd;
 109
 110         PARA_INFO_LOG("opening %s\n", conf->device_arg);
 111         ret = para_open(conf->device_arg, O_WRONLY, 0);
 112         if (ret < 0)
 113                 return ret;
 114         powd = para_calloc(sizeof(*powd));
 115         wn->private_data = powd;
 116         powd->fd = ret;
 117         ret = mark_fd_nonblocking(powd->fd);
 118         if (ret < 0)
 119                 goto err;
 120         /* set PCM format */
 121         ret = ioctl(powd->fd, SNDCTL_DSP_SETFMT, &format);
 122         if (ret < 0) {
 123                 ret = -ERRNO_TO_PARA_ERROR(errno);
 124                 goto err;
 125         }
 126         ret = -E_BAD_SAMPLE_FORMAT;
 127         if (format != FORMAT)
 128                 goto err;
 129         /* set number of channels */
 130         if (!conf->channels_given && wng->channels)
 131                 channels = *wng->channels;
 132         else
 133                 channels = conf->channels_arg;
 134         ret = -E_BAD_CHANNEL_COUNT;
 135         if (channels == 0)
 136                 goto err;
 137         powd->channels = channels;
 138         ret = ioctl(powd->fd, SNDCTL_DSP_CHANNELS, &channels);
 139         if (ret < 0) {
 140                 ret = -ERRNO_TO_PARA_ERROR(errno);
 141                 goto err;
 142         }
 143         if (powd->channels != channels)
 144                 goto err;
 145         powd->bytes_per_frame = channels * 2;
 146
 147         /*
 148          * Set sampling rate
 149          *
 150          * If we request a higher sampling rate than is supported by the
 151          * device, the the highest possible speed is automatically used. The
 152          * value actually used is returned as the new value of the argument.
 153          */
 154         if (!conf->samplerate_given && wng->samplerate)
 155                 samplerate = *wng->samplerate;
 156         else
 157                 samplerate = conf->samplerate_arg;
 158         powd->samplerate = samplerate;
 159         ret = ioctl(powd->fd, SNDCTL_DSP_SPEED, &samplerate);
 160         if (ret < 0) {
 161                 ret = -ERRNO_TO_PARA_ERROR(errno);
 162                 goto err;
 163         }
 164         if (samplerate != powd->samplerate) {
 165                 int min = PARA_MIN(samplerate, powd->samplerate),
 166                         max = PARA_MAX(samplerate, powd->samplerate);
 167                 /*
 168                  * Check whether the returned sample rate differs significantly
 169                  * from the requested one.
 170                  */
 171                 ret = -E_BAD_SAMPLERATE;
 172                 if (100 * max > 110 * min) /* more than 10% deviation */
 173                         goto err;
 174                 PARA_NOTICE_LOG("using %dHz rather than %dHz\n", samplerate,
 175                         powd->samplerate);
 176         }
 177
 178         return 1;
 179 err:
 180         close(powd->fd);
 181         free(powd);
 182         return ret;
 183 }
 184
 185 __malloc static void *oss_parse_config(const char *options)
 186 {
 187         int ret;
 188         struct oss_write_args_info *conf = para_calloc(sizeof(*conf));
 189
 190         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 191         ret = oss_cmdline_parser_string(options, conf, "oss_write");
 192         if (ret)
 193                 goto err_out;
 194         return conf;
 195 err_out:
 196         free(conf);
 197         return NULL;
 198 }
 199
 200 /**
 201  * The init function of the oss writer.
 202  *
 203  * \param w Pointer to the writer to initialize.
 204  *
 205  * \sa struct writer.
 206  */
 207 void oss_write_init(struct writer *w)
 208 {
 209         struct oss_write_args_info dummy;
 210
 211         oss_cmdline_parser_init(&dummy);
 212         w->open = oss_open;
 213         w->close = oss_close;
 214         w->pre_select = oss_pre_select;
 215         w->post_select = oss_post_select;
 216         w->parse_config = oss_parse_config;
 217         w->shutdown = NULL;
 218         w->help = (struct ggo_help) {
 219                 .short_help = oss_write_args_info_help,
 220                 .detailed_help = oss_write_args_info_detailed_help
 221         };
 222         oss_cmdline_parser_free(&dummy);
 223 }