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