oss_write.c

   1 /* Copyright (C) 2009 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file oss_write.c Paraslash's oss output plugin. */
   4
   5 #include <regex.h>
   6 #include <sys/ioctl.h>
   7 #include <sys/soundcard.h>
   8 #include <lopsub.h>
   9
  10 #include "write_cmd.lsg.h"
  11 #include "para.h"
  12 #include "fd.h"
  13 #include "string.h"
  14 #include "list.h"
  15 #include "sched.h"
  16 #include "buffer_tree.h"
  17 #include "write.h"
  18 #include "error.h"
  19
  20 /** Data specific to the oss writer. */
  21 struct private_oss_write_data {
  22         /** The file handle of the device. */
  23         int fd;
  24         /** Four bytes for stereo streams, two bytes for mono streams. */
  25         int bytes_per_frame;
  26 };
  27
  28 /*
  29  * We keep one bit of static storage to make sure only one instance of the oss
  30  * writer is running at any given time.
  31  */
  32 static bool sound_device_busy;
  33
  34 static bool sound_device_is_busy(void)
  35 {
  36         return sound_device_busy;
  37 }
  38
  39 static void set_sound_device_busy(void)
  40 {
  41         assert(!sound_device_busy);
  42         sound_device_busy = true;
  43 }
  44
  45 static void set_sound_device_idle(void)
  46 {
  47         assert(sound_device_busy);
  48         sound_device_busy = false;
  49 }
  50
  51 static int get_oss_format(enum sample_format sf)
  52 {
  53         switch (sf) {
  54         case SF_S8: return AFMT_S8;
  55         case SF_U8: return AFMT_U8;
  56         case SF_S16_LE: return AFMT_S16_LE;
  57         case SF_S16_BE: return AFMT_S16_BE;
  58         case SF_U16_LE: return AFMT_U16_LE;
  59         case SF_U16_BE: return AFMT_U16_BE;
  60         default: return -E_BAD_SAMPLE_FORMAT;
  61         }
  62 }
  63
  64 static void oss_pre_select(struct sched *s, void *context)
  65 {
  66         struct writer_node *wn = context;
  67         struct private_oss_write_data *powd = wn->private_data;
  68         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
  69
  70         if (ret == 0 || (sound_device_is_busy() && !powd))
  71                 return;
  72         if (ret < 0 || !powd)
  73                 return sched_min_delay(s);
  74         para_fd_set(powd->fd, &s->wfds, &s->max_fileno);
  75 }
  76
  77 static void oss_close(struct writer_node *wn)
  78 {
  79         struct private_oss_write_data *powd = wn->private_data;
  80
  81         if (!powd)
  82                 return;
  83         close(powd->fd);
  84         free(powd);
  85         set_sound_device_idle();
  86 }
  87
  88 /*
  89  * The Open Sound System Programmer's Guide sayeth:
  90  *
  91  * Set sampling parameters always so that number of channels (mono/stereo) is
  92  * set before selecting sampling rate (speed).  Failing to do this will make
  93  * your program incompatible with cards such as the SoundBlaster Pro which
  94  * supports 44.1 kHz in mono but just 22.05 kHz in stereo. A program which
  95  * selects 44.1 kHz speed and then sets the device to stereo mode will
  96  * incorrectly believe that the device is still in 44.1 kHz mode when actually
  97  * the speed is decreased to 22.05 kHz.
  98  */
  99 static int oss_init(struct writer_node *wn, unsigned sample_rate,
 100                 unsigned channels, int sample_format)
 101 {
 102         int ret, format;
 103         unsigned ch, rate;
 104         struct private_oss_write_data *powd = para_calloc(sizeof(*powd));
 105         const char *dev = WRITE_CMD_OPT_STRING_VAL(OSS, DEVICE, wn->lpr);
 106
 107         PARA_INFO_LOG("opening %s\n", dev);
 108         ret = para_open(dev, O_WRONLY, 0);
 109         if (ret < 0)
 110                 goto err_free;
 111         powd->fd = ret;
 112         ret = mark_fd_nonblocking(powd->fd);
 113         if (ret < 0)
 114                 goto err;
 115         /* set PCM format */
 116         ret = get_oss_format(sample_format);
 117         if (ret < 0)
 118                 return ret;
 119         sample_format = format = ret;
 120         ret = ioctl(powd->fd, SNDCTL_DSP_SETFMT, &format);
 121         if (ret < 0) {
 122                 ret = -ERRNO_TO_PARA_ERROR(errno);
 123                 PARA_ERROR_LOG("could not set sample format\n");
 124                 goto err;
 125         }
 126         ret = -E_BAD_SAMPLE_FORMAT;
 127         if (format != sample_format)
 128                 goto err;
 129         /* set number of channels */
 130         ch = channels;
 131         ret = ioctl(powd->fd, SNDCTL_DSP_CHANNELS, &ch);
 132         if (ret < 0) {
 133                 ret = -ERRNO_TO_PARA_ERROR(errno);
 134                 goto err;
 135         }
 136         ret = -E_BAD_CHANNEL_COUNT;
 137         if (ch != channels)
 138                 goto err;
 139         if (format == SF_U8 || format == SF_S8)
 140                 powd->bytes_per_frame = ch;
 141         else
 142                 powd->bytes_per_frame = ch * 2;
 143
 144         /*
 145          * Set sampling rate
 146          *
 147          * If we request a higher sampling rate than is supported by the
 148          * device, the highest possible speed is automatically used. The
 149          * value actually used is returned as the new value of the argument.
 150          */
 151         rate = sample_rate;
 152         ret = ioctl(powd->fd, SNDCTL_DSP_SPEED, &rate);
 153         if (ret < 0) {
 154                 ret = -ERRNO_TO_PARA_ERROR(errno);
 155                 goto err;
 156         }
 157         if (rate != sample_rate) {
 158                 unsigned min = PARA_MIN(rate, sample_rate),
 159                         max = PARA_MAX(rate, sample_rate);
 160                 /*
 161                  * Check whether the returned sample rate differs significantly
 162                  * from the requested one.
 163                  */
 164                 ret = -E_BAD_SAMPLERATE;
 165                 if (100 * max > 110 * min) /* more than 10% deviation */
 166                         goto err;
 167                 PARA_NOTICE_LOG("using %uHz rather than %uHz\n", rate,
 168                         sample_rate);
 169         }
 170         wn->min_iqs = powd->bytes_per_frame;
 171         wn->private_data = powd;
 172         return 1;
 173 err:
 174         close(powd->fd);
 175 err_free:
 176         free(powd);
 177         PARA_ERROR_LOG("failed to init %s: %s\n", dev, para_strerror(-ret));
 178         return ret;
 179 }
 180
 181 static int oss_post_select(__a_unused struct sched *s, void *context)
 182 {
 183         struct writer_node *wn = context;
 184         struct private_oss_write_data *powd = wn->private_data;
 185         struct btr_node *btrn = wn->btrn;
 186         size_t frames, bytes;
 187         int ret;
 188         char *data;
 189         audio_buf_info abi;
 190
 191         ret = task_get_notification(wn->task);
 192         if (ret < 0)
 193                 goto out;
 194         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 195         if (ret <= 0)
 196                 goto out;
 197         if (!powd) {
 198                 int32_t rate, ch, format;
 199
 200                 if (sound_device_is_busy())
 201                         return 0;
 202                 get_btr_sample_rate(btrn, &rate);
 203                 get_btr_channels(btrn, &ch);
 204                 get_btr_sample_format(btrn, &format);
 205                 ret = oss_init(wn, rate, ch, format);
 206                 if (ret < 0)
 207                         goto out;
 208                 set_sound_device_busy();
 209                 return 0;
 210         }
 211         btr_merge(btrn, wn->min_iqs);
 212         bytes = btr_next_buffer(btrn, &data);
 213         frames = bytes / powd->bytes_per_frame;
 214         if (!frames) { /* eof and less than a single frame available */
 215                 ret = -E_WRITE_COMMON_EOF;
 216                 goto out;
 217         }
 218         ret = 0;
 219         if (!FD_ISSET(powd->fd, &s->wfds))
 220                 goto out;
 221         /* get maximal number of bytes that can be written */
 222         ret = ioctl(powd->fd, SNDCTL_DSP_GETOSPACE, &abi);
 223         if (ret >= 0) {
 224                 size_t max_frames = abi.bytes / powd->bytes_per_frame;
 225                 if (max_frames == 0)
 226                         goto out;
 227                 /* cap number of frames to avoid sound artefacts */
 228                 frames = PARA_MIN(frames, max_frames);
 229         }
 230         ret = xwrite(powd->fd, data, frames * powd->bytes_per_frame);
 231         if (ret < 0)
 232                 goto out;
 233         btr_consume(btrn, ret);
 234         ret = 0;
 235 out:
 236         if (ret < 0)
 237                 btr_remove_node(&wn->btrn);
 238         return ret;
 239 }
 240
 241 const struct writer lsg_write_cmd_com_oss_user_data = {
 242         .pre_select = oss_pre_select,
 243         .post_select = oss_post_select,
 244         .close = oss_close,
 245 };