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