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alsasrc: Improve timestamp accuracy

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Fixes bug #635256.
This commit is contained in:
Pontus Oldberg 2011-05-09 11:50:05 +02:00 committed by Sebastian Dröge
parent 45bf51dcdf
commit 0b774e0b7c
2 changed files with 108 additions and 0 deletions
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107
ext/alsa/gstalsasrc.c
View file

@ -87,6 +87,12 @@ static gboolean gst_alsasrc_close (GstAudioSrc * asrc);
static guint gst_alsasrc_read (GstAudioSrc * asrc, gpointer data, guint length);
static guint gst_alsasrc_delay (GstAudioSrc * asrc);
static void gst_alsasrc_reset (GstAudioSrc * asrc);
static GstStateChangeReturn gst_alsasrc_change_state (GstElement * element,
GstStateChange transition);
static GstFlowReturn gst_alsasrc_create (GstBaseSrc * bsrc, guint64 offset,
guint length, GstBuffer ** outbuf);
GstClockTime gst_alsasrc_get_timestamp (GObject * object);
/* AlsaSrc signals and args */
enum
@ -199,18 +205,25 @@ static void
gst_alsasrc_class_init (GstAlsaSrcClass * klass)
{
GObjectClass *gobject_class;
GstElementClass *gstelement_class;
GstBaseSrcClass *gstbasesrc_class;
GstAudioSrcClass *gstaudiosrc_class;
GstBaseAudioSrcClass *gstbaseaudiosrc_class;
gobject_class = (GObjectClass *) klass;
gstelement_class = (GstElementClass *) klass;
gstbasesrc_class = (GstBaseSrcClass *) klass;
gstaudiosrc_class = (GstAudioSrcClass *) klass;
gstbaseaudiosrc_class = (GstBaseAudioSrcClass *) klass;
gobject_class->finalize = gst_alsasrc_finalize;
gobject_class->get_property = gst_alsasrc_get_property;
gobject_class->set_property = gst_alsasrc_set_property;
gstelement_class->change_state = GST_DEBUG_FUNCPTR (gst_alsasrc_change_state);
gstbasesrc_class->get_caps = GST_DEBUG_FUNCPTR (gst_alsasrc_getcaps);
gstbasesrc_class->create = GST_DEBUG_FUNCPTR (gst_alsasrc_create);
gstaudiosrc_class->open = GST_DEBUG_FUNCPTR (gst_alsasrc_open);
gstaudiosrc_class->prepare = GST_DEBUG_FUNCPTR (gst_alsasrc_prepare);
@ -236,6 +249,48 @@ gst_alsasrc_class_init (GstAlsaSrcClass * klass)
DEFAULT_PROP_CARD_NAME, G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
}
GstClockTime
gst_alsasrc_get_timestamp (GstAlsaSrc * asrc)
{
snd_pcm_status_t *status;
snd_htimestamp_t tstamp;
GstClockTime timestamp;
snd_pcm_uframes_t availmax;
GST_DEBUG_OBJECT (object, "Getting alsa timestamp!");
if (!asrc) {
GST_ERROR_OBJECT (asrc, "No alsa handle created yet !");
return 0;
}
if (snd_pcm_status_malloc (&status) != 0) {
GST_ERROR_OBJECT (asrc, "snd_pcm_status_malloc failed");
}
if (snd_pcm_status (asrc->handle, status) != 0) {
GST_ERROR_OBJECT (asrc, "snd_pcm_status failed");
}
/* get high resolution time stamp from driver */
snd_pcm_status_get_htstamp (status, &tstamp);
timestamp = GST_TIMESPEC_TO_TIME (tstamp);
/* Max available frames sets the depth of the buffer */
availmax = snd_pcm_status_get_avail_max (status);
/* Compensate the fact that the timestamp references the last sample */
timestamp -= gst_util_uint64_scale_int (availmax * 2, GST_SECOND, asrc->rate);
/* Compensate for the delay until the package is available */
timestamp += gst_util_uint64_scale_int (snd_pcm_status_get_delay (status),
GST_SECOND, asrc->rate);
snd_pcm_status_free (status);
GST_DEBUG ("ALSA timestamp : %" GST_TIME_FORMAT, GST_TIME_ARGS (timestamp));
return timestamp;
}
static void
gst_alsasrc_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
@ -286,6 +341,57 @@ gst_alsasrc_get_property (GObject * object, guint prop_id,
}
}
static GstStateChangeReturn
gst_alsasrc_change_state (GstElement * element, GstStateChange transition)
{
GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
GstBaseAudioSrc *src = GST_BASE_AUDIO_SRC (element);
GstAlsaSrc *asrc = GST_ALSA_SRC (element);
GstClock *clk;
switch (transition) {
/* Show the compiler that we care */
case GST_STATE_CHANGE_NULL_TO_READY:
case GST_STATE_CHANGE_READY_TO_PAUSED:
case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
case GST_STATE_CHANGE_PAUSED_TO_READY:
case GST_STATE_CHANGE_READY_TO_NULL:
break;
case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
clk = src->clock;
asrc->driver_timestamps = FALSE;
if (GST_IS_SYSTEM_CLOCK (clk)) {
gint clocktype;
g_object_get (clk, "clock-type", &clocktype, NULL);
if (clocktype == GST_CLOCK_TYPE_MONOTONIC) {
asrc->driver_timestamps = TRUE;
}
}
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
return ret;
}
static GstFlowReturn
gst_alsasrc_create (GstBaseSrc * bsrc, guint64 offset, guint length,
GstBuffer ** outbuf)
{
GstFlowReturn ret = GST_FLOW_OK;
GstAlsaSrc *asrc = GST_ALSA_SRC (bsrc);
ret =
GST_BASE_SRC_CLASS (parent_class)->create (bsrc, offset, length, outbuf);
if (asrc->driver_timestamps == TRUE && *outbuf) {
GST_BUFFER_TIMESTAMP (*outbuf) =
gst_alsasrc_get_timestamp ((GObject *) bsrc);
}
return ret;
}
static void
gst_alsasrc_init (GstAlsaSrc * alsasrc, GstAlsaSrcClass * g_class)
{
@ -293,6 +399,7 @@ gst_alsasrc_init (GstAlsaSrc * alsasrc, GstAlsaSrcClass * g_class)
alsasrc->device = g_strdup (DEFAULT_PROP_DEVICE);
alsasrc->cached_caps = NULL;
alsasrc->driver_timestamps = FALSE;
alsasrc->alsa_lock = g_mutex_new ();
}

1
ext/alsa/gstalsasrc.h
View file

@ -64,6 +64,7 @@ struct _GstAlsaSrc {
guint rate;
guint channels;
gint bytes_per_sample;
gboolean driver_timestamps;
guint buffer_time;
guint period_time;