gstreamer/ext/alsa/gstalsasink.c

/*
 * Copyright (C) 2001 CodeFactory AB
 * Copyright (C) 2001 Thomas Nyberg <thomas@codefactory.se>
 * Copyright (C) 2001-2002 Andy Wingo <apwingo@eos.ncsu.edu>
 * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "gstalsasink.h"
#include "gstalsaclock.h"

/* elementfactory information */
static GstElementDetails gst_alsa_sink_details =
GST_ELEMENT_DETAILS ("Alsa Sink",
    "Sink/Audio",
    "Output to a sound card via ALSA",
    "Thomas Nyberg <thomas@codefactory.se>, "
    "Andy Wingo <apwingo@eos.ncsu.edu>, "
    "Benjamin Otte <in7y118@public.uni-hamburg.de>");

static GstPadTemplate *gst_alsa_sink_pad_factory (void);
static GstPadTemplate *gst_alsa_sink_request_pad_factory (void);
static void gst_alsa_sink_base_init (gpointer g_class);
static void gst_alsa_sink_class_init (gpointer g_klass, gpointer class_data);
static void gst_alsa_sink_init (GstAlsaSink * this);
static inline void gst_alsa_sink_flush_one_pad (GstAlsaSink * sink, gint i);
static void gst_alsa_sink_flush_pads (GstAlsaSink * sink);
static int gst_alsa_sink_mmap (GstAlsa * this, snd_pcm_sframes_t * avail);
static int gst_alsa_sink_write (GstAlsa * this, snd_pcm_sframes_t * avail);
static void gst_alsa_sink_loop (GstElement * element);
static gboolean gst_alsa_sink_check_event (GstAlsaSink * sink, gint pad_nr);
static GstElementStateReturn gst_alsa_sink_change_state (GstElement * element);

static GstClockTime gst_alsa_sink_get_time (GstAlsa * this);

static GstAlsa *sink_parent_class = NULL;

static GstPadTemplate *
gst_alsa_sink_pad_factory (void)
{
  static GstPadTemplate *template = NULL;

  if (!template)
    template = gst_pad_template_new ("sink", GST_PAD_SINK, GST_PAD_ALWAYS,
        gst_alsa_caps (SND_PCM_FORMAT_UNKNOWN, -1, -1));

  return template;
}
static GstPadTemplate *
gst_alsa_sink_request_pad_factory (void)
{
  static GstPadTemplate *template = NULL;

  if (!template)
    template =
        gst_pad_template_new ("sink%d", GST_PAD_SINK, GST_PAD_REQUEST,
        gst_alsa_caps (SND_PCM_FORMAT_UNKNOWN, -1, 1));

  return template;
}

GType
gst_alsa_sink_get_type (void)
{
  static GType alsa_sink_type = 0;

  if (!alsa_sink_type) {
    static const GTypeInfo alsa_sink_info = {
      sizeof (GstAlsaSinkClass),
      gst_alsa_sink_base_init,
      NULL,
      gst_alsa_sink_class_init,
      NULL,
      NULL,
      sizeof (GstAlsaSink),
      0,
      (GInstanceInitFunc) gst_alsa_sink_init,
    };

    alsa_sink_type =
        g_type_register_static (GST_TYPE_ALSA_MIXER, "GstAlsaSink",
        &alsa_sink_info, 0);
  }
  return alsa_sink_type;
}

static void
gst_alsa_sink_base_init (gpointer g_class)
{
  GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

  gst_element_class_add_pad_template (element_class,
      gst_alsa_sink_pad_factory ());
  gst_element_class_add_pad_template (element_class,
      gst_alsa_sink_request_pad_factory ());

  gst_element_class_set_details (element_class, &gst_alsa_sink_details);
}

static void
gst_alsa_sink_class_init (gpointer g_class, gpointer class_data)
{
  GObjectClass *object_class;
  GstElementClass *element_class;
  GstAlsaClass *alsa_class;
  GstAlsaSinkClass *klass;

  klass = (GstAlsaSinkClass *) g_class;
  object_class = (GObjectClass *) klass;
  element_class = (GstElementClass *) klass;
  alsa_class = (GstAlsaClass *) klass;

  if (sink_parent_class == NULL)
    sink_parent_class = g_type_class_ref (GST_TYPE_ALSA_MIXER);

  alsa_class->stream = SND_PCM_STREAM_PLAYBACK;
  alsa_class->transmit_mmap = gst_alsa_sink_mmap;
  alsa_class->transmit_rw = gst_alsa_sink_write;

  element_class->change_state = gst_alsa_sink_change_state;
}
static void
gst_alsa_sink_init (GstAlsaSink * sink)
{
  GstAlsa *this = GST_ALSA (sink);

  this->pad[0] =
      gst_pad_new_from_template (gst_alsa_sink_pad_factory (), "sink");
  gst_pad_set_link_function (this->pad[0], gst_alsa_link);
  gst_pad_set_getcaps_function (this->pad[0], gst_alsa_get_caps);
  gst_pad_set_fixate_function (this->pad[0], gst_alsa_fixate);
  gst_element_add_pad (GST_ELEMENT (this), this->pad[0]);

  this->clock =
      gst_alsa_clock_new ("alsasinkclock", gst_alsa_sink_get_time, this);
  /* we hold a ref to our clock until we're disposed */
  gst_object_ref (GST_OBJECT (this->clock));
  gst_object_sink (GST_OBJECT (this->clock));

  gst_element_set_loop_function (GST_ELEMENT (this), gst_alsa_sink_loop);
}

static inline void
gst_alsa_sink_flush_one_pad (GstAlsaSink * sink, gint i)
{
  switch (sink->behaviour[i]) {
    case 0:
      if (sink->buf[i])
        gst_data_unref (GST_DATA (sink->buf[i]));
      sink->buf[i] = NULL;
      sink->data[i] = NULL;
      sink->behaviour[i] = 0;
      sink->size[i] = 0;
      break;
    case 1:
      g_free (sink->data[i]);
      sink->data[i] = NULL;
      sink->behaviour[i] = 0;
      sink->size[i] = 0;
      break;
    default:
      g_assert_not_reached ();
  }
}
static void
gst_alsa_sink_flush_pads (GstAlsaSink * sink)
{
  gint i;

  for (i = 0; i < GST_ELEMENT (sink)->numpads; i++) {
    /* flush twice to unref buffer when behaviour == 1 */
    gst_alsa_sink_flush_one_pad (sink, i);
    gst_alsa_sink_flush_one_pad (sink, i);
  }
}

/* TRUE, if everything should continue */
static gboolean
gst_alsa_sink_check_event (GstAlsaSink * sink, gint pad_nr)
{
  gboolean cont = TRUE;
  GstEvent *event = GST_EVENT (sink->buf[pad_nr]);
  GstAlsa *this = GST_ALSA (sink);

  if (event) {
    switch (GST_EVENT_TYPE (event)) {
      case GST_EVENT_EOS:
        gst_alsa_set_eos (this);
        cont = FALSE;
        break;
      case GST_EVENT_INTERRUPT:
        cont = FALSE;
        break;
      case GST_EVENT_DISCONTINUOUS:
      {
        GstClockTime value, delay;

        /* only the first pad may seek */
        if (pad_nr != 0) {
          break;
        }
        delay = (this->format == NULL) ? 0 :
            GST_SECOND * this->transmitted / this->format->rate -
            gst_alsa_sink_get_time (this);
        if (gst_event_discont_get_value (event, GST_FORMAT_TIME, &value)) {
          gst_element_set_time_delay (GST_ELEMENT (this), value, delay);
        } else if (this->format &&
            (gst_event_discont_get_value (event, GST_FORMAT_DEFAULT, &value) ||
                gst_event_discont_get_value (event, GST_FORMAT_BYTES,
                    &value))) {
          value = gst_alsa_samples_to_timestamp (this, value);
          gst_element_set_time_delay (GST_ELEMENT (this), value, delay);
        } else {
          GST_WARNING_OBJECT (this,
              "couldn't extract time from discont event. Bad things might happen!");
        }

        break;
      }
      default:
        GST_INFO_OBJECT (this, "got an unknown event (Type: %d)",
            GST_EVENT_TYPE (event));
        break;
    }
    gst_event_unref (event);
    sink->buf[pad_nr] = NULL;
  } else {
    /* the element at the top of the chain did not emit an event. */
    g_assert_not_reached ();
  }
  return cont;
}
static int
gst_alsa_sink_mmap (GstAlsa * this, snd_pcm_sframes_t * avail)
{
  snd_pcm_uframes_t offset;
  const snd_pcm_channel_area_t *dst;
  snd_pcm_channel_area_t *src;
  GstAlsaSink *sink = GST_ALSA_SINK (this);
  int i;
  int err = -1;
  int width = snd_pcm_format_physical_width (this->format->format);

  /* areas points to the memory areas that belong to gstreamer. */
  src = g_malloc0 (this->format->channels * sizeof (snd_pcm_channel_area_t));

  if (((GstElement *) this)->numpads == 1) {
    /* interleaved */
    for (i = 0; i < this->format->channels; i++) {
      src[i].addr = sink->data[0];
      src[i].first = i * width;
      src[i].step = this->format->channels * width;
    }
  } else {
    /* noninterleaved */
    for (i = 0; i < this->format->channels; i++) {
      src[i].addr = sink->data[i];
      src[i].first = 0;
      src[i].step = width;
    }
  }

  if ((err = snd_pcm_mmap_begin (this->handle, &dst, &offset, avail)) < 0) {
    GST_ERROR_OBJECT (this, "mmap failed: %s", snd_strerror (err));
    goto out;
  }

  if ((err =
          snd_pcm_areas_copy (dst, offset, src, 0, this->format->channels,
              *avail, this->format->format)) < 0) {
    snd_pcm_mmap_commit (this->handle, offset, 0);
    GST_ERROR_OBJECT (this, "data copy failed: %s", snd_strerror (err));
    goto out;
  }
  if ((err = snd_pcm_mmap_commit (this->handle, offset, *avail)) < 0) {
    GST_ERROR_OBJECT (this, "mmap commit failed: %s", snd_strerror (err));
    goto out;
  }

out:
  g_free (src);
  return err;
}
static int
gst_alsa_sink_write (GstAlsa * this, snd_pcm_sframes_t * avail)
{
  GstAlsaSink *sink = GST_ALSA_SINK (this);
  void *channels[this->format->channels];
  int err, i;

  if (((GstElement *) this)->numpads == 1) {
    /* interleaved */
    err = snd_pcm_writei (this->handle, sink->data[0], *avail);
  } else {
    /* noninterleaved */
    for (i = 0; i < this->format->channels; i++) {
      channels[i] = sink->data[i];
    }
    err = snd_pcm_writen (this->handle, channels, *avail);
  }
  /* error handling */
  if (err < 0) {
    if (err == -EPIPE) {
      gst_alsa_xrun_recovery (this);
      return 0;
    }
    GST_ERROR_OBJECT (this, "error on data access: %s", snd_strerror (err));
  }
  return err;
}
static void
gst_alsa_sink_loop (GstElement * element)
{
  snd_pcm_sframes_t avail, avail2, copied, sample_diff, max_discont;
  snd_pcm_uframes_t samplestamp, expected;
  gint i;
  guint bytes;                  /* per channel */
  GstAlsa *this = GST_ALSA (element);
  GstAlsaSink *sink = GST_ALSA_SINK (element);

  g_return_if_fail (sink != NULL);

sink_restart:

  avail = gst_alsa_update_avail (this);
  if (avail == -EPIPE)
    goto sink_restart;
  if (avail < 0)
    return;
  if (avail > 0) {

    /* Not enough space. We grab data nonetheless and sleep afterwards */
    if (avail < this->period_size) {
      avail = this->period_size;
    }

    /* check how many bytes we still have in all our bytestreams */
    /* initialize this value to a somewhat sane state, we might alloc this much data below (which would be a bug, but who knows)... */
    bytes = this->period_size * this->period_count * element->numpads * 8;      /* must be > max sample size in bytes */
    for (i = 0; i < element->numpads; i++) {
      g_assert (this->pad[i] != NULL);
      while (sink->size[i] == 0) {
        if (!sink->buf[i])
          sink->buf[i] = GST_BUFFER (gst_pad_pull (this->pad[i]));
        if (GST_IS_EVENT (sink->buf[i])) {
          if (gst_alsa_sink_check_event (sink, i))
            continue;
          return;
        }
        /* caps nego failed somewhere */
        if (this->format == NULL) {
          GST_ELEMENT_ERROR (this, CORE, NEGOTIATION, (NULL),
              ("ALSA format not negotiated"));
        }
        samplestamp =
            gst_alsa_timestamp_to_samples (this,
            GST_BUFFER_TIMESTAMP (sink->buf[i]));
        max_discont = gst_alsa_timestamp_to_samples (this, this->max_discont);
        /* optimization: check if we're using our own clock
         * This optimization is important because if we're using our own clock 
         * gst_element_get_time calls snd_pcm_delay and the following code assumes
         * that both calls return the same value. However they can be wildly 
         * different, since snd_pcm_delay goes deep into the kernel.
         */
        if (gst_element_get_clock (element) == GST_CLOCK (this->clock)) {
          /* FIXME: this is ugly because of the variables it uses but I don't know a 
           * better way to get this info */
          if (element->base_time > this->clock->start_time) {
            expected =
                this->transmitted - gst_alsa_timestamp_to_samples (this,
                element->base_time - this->clock->start_time);
          } else {
            expected =
                this->transmitted + gst_alsa_timestamp_to_samples (this,
                this->clock->start_time - element->base_time);
          }
        } else {
          if (snd_pcm_delay (this->handle, &sample_diff) != 0) {
            sample_diff = 0;
          }
          expected =
              gst_alsa_timestamp_to_samples (this,
              gst_element_get_time (GST_ELEMENT (this))) + sample_diff;
          /* actual diff = buffer samplestamp - played - to_play */
        }
        sample_diff = samplestamp - expected;

        if ((!GST_BUFFER_TIMESTAMP_IS_VALID (sink->buf[i])) ||
            (-max_discont <= sample_diff && sample_diff <= max_discont)) {

          /* difference between expected and current is < GST_ALSA_DEVIATION */
        no_difference:
          sink->size[i] = sink->buf[i]->size;
          sink->data[i] = sink->buf[i]->data;
          sink->behaviour[i] = 0;
        } else if (sample_diff > 0) {
          /* there are empty samples in front of us, fill them with silence */
          int samples = MIN (bytes, sample_diff) *
              (element->numpads == 1 ? this->format->channels : 1);
          int size =
              samples * snd_pcm_format_physical_width (this->format->format) /
              8;
          GST_INFO_OBJECT (this,
              "Allocating %d bytes (%ld samples) now to resync: sample %lu expected, but got %ld",
              size, MIN (bytes, sample_diff), expected, samplestamp);
          sink->data[i] = g_try_malloc (size);
          if (!sink->data[i]) {
            GST_WARNING_OBJECT (this,
                "error allocating %d bytes, buffers unsynced now.", size);
            goto no_difference;
          }
          sink->size[i] = size;
          if (0 != snd_pcm_format_set_silence (this->format->format,
                  sink->data[i], samples)) {
            GST_WARNING_OBJECT (this,
                "error silencing buffer, enjoy the noise.");
          }
          sink->behaviour[i] = 1;
        } else if (gst_alsa_samples_to_bytes (this,
                -sample_diff) >= sink->buf[i]->size) {
          GST_INFO_OBJECT (this,
              "Skipping %lu samples to resync (complete buffer): sample %lu expected, but got %ld",
              gst_alsa_bytes_to_samples (this, sink->buf[i]->size), expected,
              samplestamp);
          /* this buffer is way behind */
          gst_buffer_unref (sink->buf[i]);
          sink->buf[i] = NULL;
          continue;
        } else if (sample_diff < 0) {
          gint difference = gst_alsa_samples_to_bytes (this, -sample_diff);

          GST_INFO_OBJECT (this,
              "Skipping %lu samples to resync: sample %lu expected, but got %ld",
              (gulong) - sample_diff, expected, samplestamp);
          /* this buffer is only a bit behind */
          sink->size[i] = sink->buf[i]->size - difference;
          sink->data[i] = sink->buf[i]->data + difference;
          sink->behaviour[i] = 0;
        } else {
          g_assert_not_reached ();
        }
      }
      bytes = MIN (bytes, sink->size[i]);
    }

    avail = MIN (avail, gst_alsa_bytes_to_samples (this, bytes));

    /* wait until the hw buffer has enough space */
    while (gst_element_get_state (element) == GST_STATE_PLAYING
        && (avail2 = gst_alsa_update_avail (this)) < avail) {
      if (avail2 <= -EPIPE)
        goto sink_restart;
      if (avail2 < 0)
        return;
      if (avail2 < avail
          && snd_pcm_state (this->handle) != SND_PCM_STATE_RUNNING)
        if (!gst_alsa_start (this))
          return;
      if (gst_alsa_pcm_wait (this) == FALSE)
        return;
    }

    /* FIXME: lotsa stuff can have happened while fetching data. Do we need to check something? */

    /* put this data into alsa */
    if ((copied = this->transmit (this, &avail)) < 0)
      return;
    /* update our clock */
    this->transmitted += copied;
    /* flush the data */
    bytes = gst_alsa_samples_to_bytes (this, copied);
    for (i = 0; i < element->numpads; i++) {
      if ((sink->size[i] -= bytes) == 0) {
        gst_alsa_sink_flush_one_pad (sink, i);
        continue;
      }
      g_assert (sink->size[i] > 0);
      if (sink->behaviour[i] != 1)
        sink->data[i] += bytes;
    }
  }

  if (snd_pcm_state (this->handle) != SND_PCM_STATE_RUNNING
      && snd_pcm_avail_update (this->handle) == 0) {
    gst_alsa_start (this);
  }

}

static GstElementStateReturn
gst_alsa_sink_change_state (GstElement * element)
{
  GstAlsaSink *sink;

  g_return_val_if_fail (element != NULL, FALSE);
  sink = GST_ALSA_SINK (element);

  switch (GST_STATE_TRANSITION (element)) {
    case GST_STATE_NULL_TO_READY:
    case GST_STATE_READY_TO_PAUSED:
    case GST_STATE_PAUSED_TO_PLAYING:
    case GST_STATE_PLAYING_TO_PAUSED:
      break;
    case GST_STATE_PAUSED_TO_READY:
      gst_alsa_sink_flush_pads (sink);
      break;
    case GST_STATE_READY_TO_NULL:
      break;
    default:
      g_assert_not_reached ();
  }

  if (GST_ELEMENT_CLASS (sink_parent_class)->change_state)
    return GST_ELEMENT_CLASS (sink_parent_class)->change_state (element);

  return GST_STATE_SUCCESS;
}

static GstClockTime
gst_alsa_sink_get_time (GstAlsa * this)
{
  snd_pcm_sframes_t delay;

  if (!this->format)
    return 0;
  if (snd_pcm_delay (this->handle, &delay) != 0) {
    return this->transmitted / this->format->rate;
  }
  if (this->transmitted <= delay) {
    return 0;
  }

  return GST_SECOND * (this->transmitted - delay) / this->format->rate;
}