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alsasrc: fail gracefully when ALSA does not give timestamps

Browse source 
https://bugzilla.gnome.org/show_bug.cgi?id=660170
This commit is contained in:
Vincent Penquerc'h 2011-09-27 00:26:29 +01:00 committed by Sebastian Dröge
parent 9117681b35
commit c7282a5718
2 changed files with 36 additions and 5 deletions
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40
ext/alsa/gstalsasrc.c
View file

@ -254,37 +254,63 @@ gst_alsasrc_get_timestamp (GstAlsaSrc * src)
snd_htimestamp_t tstamp;
GstClockTime timestamp;
snd_pcm_uframes_t availmax;
gint64 offset;
GST_DEBUG_OBJECT (src, "Getting alsa timestamp!");
if (!src) {
GST_ERROR_OBJECT (src, "No alsa handle created yet !");
return 0;
return GST_CLOCK_TIME_NONE;
}
if (snd_pcm_status_malloc (&status) != 0) {
GST_ERROR_OBJECT (src, "snd_pcm_status_malloc failed");
return GST_CLOCK_TIME_NONE;
}
if (snd_pcm_status (src->handle, status) != 0) {
GST_ERROR_OBJECT (src, "snd_pcm_status failed");
snd_pcm_status_free (status);
return GST_CLOCK_TIME_NONE;
}
/* get high resolution time stamp from driver */
snd_pcm_status_get_htstamp (status, &tstamp);
timestamp = GST_TIMESPEC_TO_TIME (tstamp);
GST_DEBUG_OBJECT (src, "Base ts: %" GST_TIME_FORMAT,
GST_TIME_ARGS (timestamp));
if (timestamp == 0) {
/* This timestamp is supposed to represent the last sample, so 0 (which
can be returned on some ALSA setups (such as mine)) must mean that it
is invalid, unless there's just one sample, but we'll ignore that. */
GST_WARNING_OBJECT (src,
"No timestamp returned from snd_pcm_status_get_htstamp");
return GST_CLOCK_TIME_NONE;
}
/* 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, src->rate);
offset = -gst_util_uint64_scale_int (availmax * 2, GST_SECOND, src->rate);
/* Compensate for the delay until the package is available */
timestamp += gst_util_uint64_scale_int (snd_pcm_status_get_delay (status),
offset += gst_util_uint64_scale_int (snd_pcm_status_get_delay (status),
GST_SECOND, src->rate);
snd_pcm_status_free (status);
/* just in case, should not happen */
if (-offset > timestamp)
timestamp = 0;
else
timestamp -= offset;
/* Take first ts into account */
if (src->first_alsa_ts == GST_CLOCK_TIME_NONE) {
src->first_alsa_ts = timestamp;
}
timestamp -= src->first_alsa_ts;
GST_DEBUG_OBJECT (src, "ALSA timestamp : %" GST_TIME_FORMAT,
GST_TIME_ARGS (timestamp));
return timestamp;
@ -384,8 +410,10 @@ gst_alsasrc_create (GstBaseSrc * bsrc, guint64 offset, guint length,
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 ((GstAlsaSrc *) bsrc);
GstClockTime ts = gst_alsasrc_get_timestamp (asrc);
if (GST_CLOCK_TIME_IS_VALID (ts)) {
GST_BUFFER_TIMESTAMP (*outbuf) = ts;
}
}
return ret;
@ -399,6 +427,7 @@ gst_alsasrc_init (GstAlsaSrc * alsasrc, GstAlsaSrcClass * g_class)
alsasrc->device = g_strdup (DEFAULT_PROP_DEVICE);
alsasrc->cached_caps = NULL;
alsasrc->driver_timestamps = FALSE;
alsasrc->first_alsa_ts = GST_CLOCK_TIME_NONE;
alsasrc->alsa_lock = g_mutex_new ();
}
@ -943,6 +972,7 @@ gst_alsasrc_reset (GstAudioSrc * asrc)
GST_DEBUG_OBJECT (alsa, "prepare");
CHECK (snd_pcm_prepare (alsa->handle), prepare_error);
GST_DEBUG_OBJECT (alsa, "reset done");
alsa->first_alsa_ts = GST_CLOCK_TIME_NONE;
GST_ALSA_SRC_UNLOCK (asrc);
return;

1
ext/alsa/gstalsasrc.h
View file

@ -65,6 +65,7 @@ struct _GstAlsaSrc {
guint channels;
gint bytes_per_sample;
gboolean driver_timestamps;
GstClockTime first_alsa_ts;
guint buffer_time;
guint period_time;