gstreamer/gst-libs/gst/app/gstappsink.c
Wim Taymans 0c5d01b59f gst-libs/gst/app/gstappsink.*: Add more docs.
Original commit message from CVS:
* gst-libs/gst/app/gstappsink.c: (gst_app_sink_class_init),
(gst_app_sink_init), (gst_app_sink_set_property),
(gst_app_sink_get_property), (gst_app_sink_event),
(gst_app_sink_preroll), (gst_app_sink_render),
(gst_app_sink_set_emit_signals), (gst_app_sink_get_emit_signals),
(gst_app_sink_set_max_buffers), (gst_app_sink_get_max_buffers),
(gst_app_sink_pull_buffer):
* gst-libs/gst/app/gstappsink.h:
Add more docs.
Add signals for when preroll and render buffers are available.
Add property to control signal emission.
Add property to control the max queue size.
2008-04-25 18:18:47 +00:00

850 lines
24 KiB
C

/* GStreamer
* Copyright (C) 2007 David Schleef <ds@schleef.org>
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/gst.h>
#include <gst/base/gstbasesink.h>
#include <gst/gstbuffer.h>
#include <string.h>
#include "gstappsink.h"
GST_DEBUG_CATEGORY (app_sink_debug);
#define GST_CAT_DEFAULT app_sink_debug
static const GstElementDetails app_sink_details =
GST_ELEMENT_DETAILS ("AppSink",
"Generic/Sink",
"Allow the application to get access to raw buffer",
"David Schleef <ds@schleef.org>, Wim Taymans <wim.taymans@gmail.com");
enum
{
/* signals */
SIGNAL_EOS,
SIGNAL_NEW_PREROLL,
SIGNAL_NEW_BUFFER,
/* acions */
SIGNAL_PULL_PREROLL,
SIGNAL_PULL_BUFFER,
LAST_SIGNAL
};
#define DEFAULT_PROP_EOS TRUE
#define DEFAULT_PROP_EMIT_SIGNALS TRUE
#define DEFAULT_PROP_MAX_BUFFERS 0
enum
{
PROP_0,
PROP_CAPS,
PROP_EOS,
PROP_EMIT_SIGNALS,
PROP_MAX_BUFFERS,
PROP_LAST,
};
static GstStaticPadTemplate gst_app_sink_template =
GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS_ANY);
static void gst_app_sink_dispose (GObject * object);
static void gst_app_sink_finalize (GObject * object);
static void gst_app_sink_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec);
static void gst_app_sink_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec);
static gboolean gst_app_sink_start (GstBaseSink * psink);
static gboolean gst_app_sink_stop (GstBaseSink * psink);
static gboolean gst_app_sink_event (GstBaseSink * sink, GstEvent * event);
static GstFlowReturn gst_app_sink_preroll (GstBaseSink * psink,
GstBuffer * buffer);
static GstFlowReturn gst_app_sink_render (GstBaseSink * psink,
GstBuffer * buffer);
static GstCaps *gst_app_sink_getcaps (GstBaseSink * psink);
static guint gst_app_sink_signals[LAST_SIGNAL] = { 0 };
GST_BOILERPLATE (GstAppSink, gst_app_sink, GstBaseSink, GST_TYPE_BASE_SINK);
void
gst_app_marshal_OBJECT__VOID (GClosure * closure,
GValue * return_value,
guint n_param_values,
const GValue * param_values,
gpointer invocation_hint, gpointer marshal_data)
{
typedef GstBuffer *(*GMarshalFunc_OBJECT__VOID) (gpointer data1,
gpointer data2);
register GMarshalFunc_OBJECT__VOID callback;
register GCClosure *cc = (GCClosure *) closure;
register gpointer data1, data2;
GstBuffer *v_return;
g_return_if_fail (return_value != NULL);
g_return_if_fail (n_param_values == 1);
if (G_CCLOSURE_SWAP_DATA (closure)) {
data1 = closure->data;
data2 = g_value_peek_pointer (param_values + 0);
} else {
data1 = g_value_peek_pointer (param_values + 0);
data2 = closure->data;
}
callback =
(GMarshalFunc_OBJECT__VOID) (marshal_data ? marshal_data : cc->callback);
v_return = callback (data1, data2);
gst_value_take_buffer (return_value, v_return);
}
static void
gst_app_sink_base_init (gpointer g_class)
{
GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
GST_DEBUG_CATEGORY_INIT (app_sink_debug, "appsink", 0, "appsink element");
gst_element_class_set_details (element_class, &app_sink_details);
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&gst_app_sink_template));
}
static void
gst_app_sink_class_init (GstAppSinkClass * klass)
{
GObjectClass *gobject_class = (GObjectClass *) klass;
GstBaseSinkClass *basesink_class = (GstBaseSinkClass *) klass;
gobject_class->dispose = gst_app_sink_dispose;
gobject_class->finalize = gst_app_sink_finalize;
gobject_class->set_property = gst_app_sink_set_property;
gobject_class->get_property = gst_app_sink_get_property;
g_object_class_install_property (gobject_class, PROP_CAPS,
g_param_spec_boxed ("caps", "Caps",
"The caps of the sink pad", GST_TYPE_CAPS,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (gobject_class, PROP_EOS,
g_param_spec_boolean ("eos", "EOS",
"Check if the sink is EOS or not started", DEFAULT_PROP_EOS,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (gobject_class, PROP_EMIT_SIGNALS,
g_param_spec_boolean ("emit-signals", "Emit signals",
"Emit new-preroll and new-buffer signals", DEFAULT_PROP_EMIT_SIGNALS,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (gobject_class, PROP_MAX_BUFFERS,
g_param_spec_uint ("max-buffers", "Max Buffers",
"Control the maximum buffers to queue internally (0 = unlimited)",
0, G_MAXUINT, DEFAULT_PROP_MAX_BUFFERS,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
/**
* GstAppSink::eos:
* @appsink: the appsink element that emited the signal
*
* Signal that the end-of-stream has been reached. This signal is emited from
* the steaming thread.
*/
gst_app_sink_signals[SIGNAL_EOS] =
g_signal_new ("eos", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GstAppSinkClass, eos),
NULL, NULL, g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0, G_TYPE_NONE);
/**
* GstAppSink::new-preroll:
* @appsink: the appsink element that emited the signal
*
* Signal that a new preroll buffer is available.
*
* This signal is emited from the steaming thread and only when the
* "emit-signals" property is %TRUE.
*
* The new preroll buffer can be retrieved with the "pull-preroll" action
* signal or gst_app_sink_pull_preroll() either from this signal callback
* or from any other thread.
*
* Note that this signal is only emited when the "emit-signals" property is
* set to %TRUE, which it is not by default for performance reasons.
*/
gst_app_sink_signals[SIGNAL_NEW_PREROLL] =
g_signal_new ("new-preroll", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GstAppSinkClass, new_preroll),
NULL, NULL, g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0, G_TYPE_NONE);
/**
* GstAppSink::new-buffer:
* @appsink: the appsink element that emited the signal
*
* Signal that a new buffer is available.
*
* This signal is emited from the steaming thread and only when the
* "emit-signals" property is %TRUE.
*
* The new preroll buffer can be retrieved with the "pull-buffer" action
* signal or gst_app_sink_pull_buffer() either from this signal callback
* or from any other thread.
*
* Note that this signal is only emited when the "emit-signals" property is
* set to %TRUE, which it is not by default for performance reasons.
*/
gst_app_sink_signals[SIGNAL_NEW_BUFFER] =
g_signal_new ("new-buffer", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GstAppSinkClass, new_buffer),
NULL, NULL, g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0, G_TYPE_NONE);
/**
* GstAppSink::pull-preroll:
* @appsink: the appsink element to emit this signal on
*
* Get the last preroll buffer in @appsink. This was the buffer that caused the
* appsink to preroll in the PAUSED state. This buffer can be pulled many times
* and remains available to the application even after EOS.
*
* This function is typically used when dealing with a pipeline in the PAUSED
* state. Calling this function after doing a seek will give the buffer right
* after the seek position.
*
* Note that the preroll buffer will also be returned as the first buffer
* when calling gst_app_sink_pull_buffer() or the "pull-buffer" action signal.
*
* If an EOS event was received before any buffers, this function returns
* %NULL. Use gst_app_sink_is_eos () to check for the EOS condition.
*
* This function blocks until a preroll buffer or EOS is received or the appsink
* element is set to the READY/NULL state.
*
* Returns: a #GstBuffer or NULL when the appsink is stopped or EOS.
*/
gst_app_sink_signals[SIGNAL_PULL_PREROLL] =
g_signal_new ("pull-preroll", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION, G_STRUCT_OFFSET (GstAppSinkClass,
pull_preroll), NULL, NULL, gst_app_marshal_OBJECT__VOID,
GST_TYPE_BUFFER, 0, G_TYPE_NONE);
/**
* GstAppSink::pull-buffer:
* @appsink: the appsink element to emit this signal on
*
* This function blocks until a buffer or EOS becomes available or the appsink
* element is set to the READY/NULL state.
*
* This function will only return buffers when the appsink is in the PLAYING
* state. All rendered buffers will be put in a queue so that the application
* can pull buffers at its own rate. Note that when the application does not
* pull buffers fast enough, the queued buffers could consume a lot of memory,
* especially when dealing with raw video frames.
*
* If an EOS event was received before any buffers, this function returns
* %NULL. Use gst_app_sink_is_eos () to check for the EOS condition.
*
* Returns: a #GstBuffer or NULL when the appsink is stopped or EOS.
*/
gst_app_sink_signals[SIGNAL_PULL_PREROLL] =
g_signal_new ("pull-buffer", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION, G_STRUCT_OFFSET (GstAppSinkClass,
pull_buffer), NULL, NULL, gst_app_marshal_OBJECT__VOID,
GST_TYPE_BUFFER, 0, G_TYPE_NONE);
basesink_class->start = gst_app_sink_start;
basesink_class->stop = gst_app_sink_stop;
basesink_class->event = gst_app_sink_event;
basesink_class->preroll = gst_app_sink_preroll;
basesink_class->render = gst_app_sink_render;
basesink_class->get_caps = gst_app_sink_getcaps;
klass->pull_preroll = gst_app_sink_pull_preroll;
klass->pull_buffer = gst_app_sink_pull_buffer;
}
static void
gst_app_sink_init (GstAppSink * appsink, GstAppSinkClass * klass)
{
appsink->mutex = g_mutex_new ();
appsink->cond = g_cond_new ();
appsink->queue = g_queue_new ();
appsink->emit_signals = DEFAULT_PROP_EMIT_SIGNALS;
appsink->max_buffers = DEFAULT_PROP_MAX_BUFFERS;
}
static void
gst_app_sink_dispose (GObject * obj)
{
GstAppSink *appsink = GST_APP_SINK (obj);
GstBuffer *buffer;
if (appsink->caps) {
gst_caps_unref (appsink->caps);
appsink->caps = NULL;
}
if (appsink->preroll) {
gst_buffer_unref (appsink->preroll);
appsink->preroll = NULL;
}
g_mutex_lock (appsink->mutex);
while ((buffer = g_queue_pop_head (appsink->queue)))
gst_buffer_unref (buffer);
g_mutex_unlock (appsink->mutex);
G_OBJECT_CLASS (parent_class)->dispose (obj);
}
static void
gst_app_sink_finalize (GObject * obj)
{
GstAppSink *appsink = GST_APP_SINK (obj);
g_mutex_free (appsink->mutex);
g_cond_free (appsink->cond);
g_queue_free (appsink->queue);
G_OBJECT_CLASS (parent_class)->finalize (obj);
}
static void
gst_app_sink_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstAppSink *appsink = GST_APP_SINK (object);
switch (prop_id) {
case PROP_CAPS:
gst_app_sink_set_caps (appsink, gst_value_get_caps (value));
break;
case PROP_EMIT_SIGNALS:
gst_app_sink_set_emit_signals (appsink, g_value_get_boolean (value));
break;
case PROP_MAX_BUFFERS:
gst_app_sink_set_max_buffers (appsink, g_value_get_uint (value));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_app_sink_get_property (GObject * object, guint prop_id, GValue * value,
GParamSpec * pspec)
{
GstAppSink *appsink = GST_APP_SINK (object);
switch (prop_id) {
case PROP_CAPS:
{
GstCaps *caps;
caps = gst_app_sink_get_caps (appsink);
gst_value_set_caps (value, caps);
if (caps)
gst_caps_unref (caps);
break;
}
case PROP_EOS:
g_value_set_boolean (value, gst_app_sink_is_eos (appsink));
break;
case PROP_EMIT_SIGNALS:
g_value_set_boolean (value, gst_app_sink_get_emit_signals (appsink));
break;
case PROP_MAX_BUFFERS:
g_value_set_uint (value, gst_app_sink_get_max_buffers (appsink));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_app_sink_flush_unlocked (GstAppSink * appsink)
{
GstBuffer *buffer;
GST_DEBUG_OBJECT (appsink, "flushing appsink");
appsink->is_eos = FALSE;
gst_buffer_replace (&appsink->preroll, NULL);
while ((buffer = g_queue_pop_head (appsink->queue)))
gst_buffer_unref (buffer);
g_cond_signal (appsink->cond);
}
static gboolean
gst_app_sink_start (GstBaseSink * psink)
{
GstAppSink *appsink = GST_APP_SINK (psink);
g_mutex_lock (appsink->mutex);
appsink->is_eos = FALSE;
appsink->started = TRUE;
GST_DEBUG_OBJECT (appsink, "starting");
g_mutex_unlock (appsink->mutex);
return TRUE;
}
static gboolean
gst_app_sink_stop (GstBaseSink * psink)
{
GstAppSink *appsink = GST_APP_SINK (psink);
g_mutex_lock (appsink->mutex);
GST_DEBUG_OBJECT (appsink, "stopping");
appsink->started = FALSE;
gst_app_sink_flush_unlocked (appsink);
g_mutex_unlock (appsink->mutex);
return TRUE;
}
static gboolean
gst_app_sink_event (GstBaseSink * sink, GstEvent * event)
{
GstAppSink *appsink = GST_APP_SINK (sink);
switch (event->type) {
case GST_EVENT_EOS:
g_mutex_lock (appsink->mutex);
GST_DEBUG_OBJECT (appsink, "receiving EOS");
appsink->is_eos = TRUE;
g_cond_signal (appsink->cond);
g_mutex_unlock (appsink->mutex);
/* emit EOS now */
g_signal_emit (appsink, gst_app_sink_signals[SIGNAL_EOS], 0);
break;
case GST_EVENT_FLUSH_START:
break;
case GST_EVENT_FLUSH_STOP:
g_mutex_lock (appsink->mutex);
GST_DEBUG_OBJECT (appsink, "received FLUSH_STOP");
gst_app_sink_flush_unlocked (appsink);
g_mutex_unlock (appsink->mutex);
break;
default:
break;
}
return TRUE;
}
static GstFlowReturn
gst_app_sink_preroll (GstBaseSink * psink, GstBuffer * buffer)
{
GstAppSink *appsink = GST_APP_SINK (psink);
gboolean emit;
g_mutex_lock (appsink->mutex);
GST_DEBUG_OBJECT (appsink, "setting preroll buffer %p", buffer);
gst_buffer_replace (&appsink->preroll, buffer);
g_cond_signal (appsink->cond);
emit = appsink->emit_signals;
g_mutex_unlock (appsink->mutex);
if (emit)
g_signal_emit (appsink, gst_app_sink_signals[SIGNAL_NEW_PREROLL], 0);
return GST_FLOW_OK;
}
static GstFlowReturn
gst_app_sink_render (GstBaseSink * psink, GstBuffer * buffer)
{
GstAppSink *appsink = GST_APP_SINK (psink);
gboolean emit;
g_mutex_lock (appsink->mutex);
GST_DEBUG_OBJECT (appsink, "pushing render buffer %p on queue", buffer);
while (appsink->max_buffers > 0 &&
appsink->queue->length >= appsink->max_buffers) {
/* FIXME, do proper unlocking when flushing */
g_cond_wait (appsink->cond, appsink->mutex);
if (!appsink->started)
goto not_started;
}
g_queue_push_tail (appsink->queue, gst_buffer_ref (buffer));
g_cond_signal (appsink->cond);
emit = appsink->emit_signals;
g_mutex_unlock (appsink->mutex);
if (emit)
g_signal_emit (appsink, gst_app_sink_signals[SIGNAL_NEW_BUFFER], 0);
return GST_FLOW_OK;
not_started:
{
GST_DEBUG_OBJECT (appsink, "we stopped");
g_mutex_unlock (appsink->mutex);
return GST_FLOW_WRONG_STATE;
}
}
static GstCaps *
gst_app_sink_getcaps (GstBaseSink * psink)
{
GstCaps *caps;
GstAppSink *appsink = GST_APP_SINK (psink);
GST_OBJECT_LOCK (appsink);
if ((caps = appsink->caps))
gst_caps_ref (caps);
GST_DEBUG_OBJECT (appsink, "got caps %" GST_PTR_FORMAT, caps);
GST_OBJECT_UNLOCK (appsink);
return caps;
}
/* external API */
/**
* gst_app_sink_set_caps:
* @appsink: a #GstAppSink
* @caps: caps to set
*
* Set the capabilities on the appsink element. This function takes
* a copy of the caps structure. After calling this method, the sink will only
* accept caps that match @caps. If @caps is non-fixed, you must check the caps
* on the buffers to get the actual used caps.
*/
void
gst_app_sink_set_caps (GstAppSink * appsink, const GstCaps * caps)
{
GstCaps *old;
g_return_if_fail (appsink != NULL);
g_return_if_fail (GST_IS_APP_SINK (appsink));
GST_OBJECT_LOCK (appsink);
GST_DEBUG_OBJECT (appsink, "setting caps to %" GST_PTR_FORMAT, caps);
old = appsink->caps;
if (caps)
appsink->caps = gst_caps_copy (caps);
else
appsink->caps = NULL;
if (old)
gst_caps_unref (old);
GST_OBJECT_UNLOCK (appsink);
}
/**
* gst_app_sink_get_caps:
* @appsink: a #GstAppSink
*
* Get the configured caps on @appsink.
*
* Returns: the #GstCaps accepted by the sink. gst_caps_unref() after usage.
*/
GstCaps *
gst_app_sink_get_caps (GstAppSink * appsink)
{
GstCaps *caps;
g_return_val_if_fail (appsink != NULL, NULL);
g_return_val_if_fail (GST_IS_APP_SINK (appsink), NULL);
GST_OBJECT_LOCK (appsink);
if ((caps = appsink->caps))
gst_caps_ref (caps);
GST_DEBUG_OBJECT (appsink, "getting caps of %" GST_PTR_FORMAT, caps);
GST_OBJECT_UNLOCK (appsink);
return caps;
}
/**
* gst_app_sink_is_eos:
* @appsink: a #GstAppSink
*
* Check if @appsink is EOS, which is when no more buffers can be pulled because
* an EOS event was received.
*
* This function also returns %TRUE when the appsink is not in the PAUSED or
* PLAYING state.
*
* Returns: %TRUE if no more buffers can be pulled and the appsink is EOS.
*/
gboolean
gst_app_sink_is_eos (GstAppSink * appsink)
{
gboolean ret;
g_return_val_if_fail (appsink != NULL, FALSE);
g_return_val_if_fail (GST_IS_APP_SINK (appsink), FALSE);
g_mutex_lock (appsink->mutex);
if (!appsink->started)
goto not_started;
if (appsink->is_eos && g_queue_is_empty (appsink->queue)) {
GST_DEBUG_OBJECT (appsink, "we are EOS and the queue is empty");
ret = TRUE;
} else {
GST_DEBUG_OBJECT (appsink, "we are not yet EOS");
ret = FALSE;
}
g_mutex_unlock (appsink->mutex);
return ret;
not_started:
{
GST_DEBUG_OBJECT (appsink, "we are stopped, return TRUE");
g_mutex_unlock (appsink->mutex);
return TRUE;
}
}
/**
* gst_app_sink_set_emit_signals:
* @appsink: a #GstAppSink
* @emit: the new state
*
* Make appsink emit the "new-preroll" and "new-buffer" signals. This option is
* by default disabled because signal emission is expensive and unneeded when
* the application prefers to operate in pull mode.
*/
void
gst_app_sink_set_emit_signals (GstAppSink * appsink, gboolean emit)
{
g_return_if_fail (GST_IS_APP_SINK (appsink));
g_mutex_lock (appsink->mutex);
appsink->emit_signals = emit;
g_mutex_unlock (appsink->mutex);
}
/**
* gst_app_sink_get_emit_signals:
* @appsink: a #GstAppSink
*
* Check if appsink will emit the "new-preroll" and "new-buffer" signals.
*
* Returns: %TRUE if @appsink is emiting the "new-preroll" and "new-buffer"
* signals.
*/
gboolean
gst_app_sink_get_emit_signals (GstAppSink * appsink)
{
gboolean result;
g_return_val_if_fail (GST_IS_APP_SINK (appsink), FALSE);
g_mutex_lock (appsink->mutex);
result = appsink->emit_signals;
g_mutex_unlock (appsink->mutex);
return result;
}
/**
* gst_app_sink_set_max_buffers:
* @appsink: a #GstAppSink
* @max: the maximum number of buffers to queue
*
* Set the maximum amount of buffers that can be queued in @appsink. After this
* amount of buffers are queued in appsink, any more buffers will block upstream
* elements until a buffer is pulled from @appsink.
*/
void
gst_app_sink_set_max_buffers (GstAppSink * appsink, guint max)
{
g_return_if_fail (GST_IS_APP_SINK (appsink));
g_mutex_lock (appsink->mutex);
if (max != appsink->max_buffers) {
appsink->max_buffers = max;
/* signal the change */
g_cond_signal (appsink->cond);
}
g_mutex_unlock (appsink->mutex);
}
/**
* gst_app_sink_get_max_buffers:
* @appsink: a #GstAppSink
*
* Get the maximum amount of buffers that can be queued in @appsink.
*
* Returns: The maximum amount of buffers that can be queued.
*/
guint
gst_app_sink_get_max_buffers (GstAppSink * appsink)
{
guint result;
g_return_val_if_fail (GST_IS_APP_SINK (appsink), 0);
g_mutex_lock (appsink->mutex);
result = appsink->max_buffers;
g_mutex_unlock (appsink->mutex);
return result;
}
/**
* gst_app_sink_pull_preroll:
* @appsink: a #GstAppSink
*
* Get the last preroll buffer in @appsink. This was the buffer that caused the
* appsink to preroll in the PAUSED state. This buffer can be pulled many times
* and remains available to the application even after EOS.
*
* This function is typically used when dealing with a pipeline in the PAUSED
* state. Calling this function after doing a seek will give the buffer right
* after the seek position.
*
* Note that the preroll buffer will also be returned as the first buffer
* when calling gst_app_sink_pull_buffer().
*
* If an EOS event was received before any buffers, this function returns
* %NULL. Use gst_app_sink_is_eos () to check for the EOS condition.
*
* This function blocks until a preroll buffer or EOS is received or the appsink
* element is set to the READY/NULL state.
*
* Returns: a #GstBuffer or NULL when the appsink is stopped or EOS.
*/
GstBuffer *
gst_app_sink_pull_preroll (GstAppSink * appsink)
{
GstBuffer *buf = NULL;
g_return_val_if_fail (appsink != NULL, NULL);
g_return_val_if_fail (GST_IS_APP_SINK (appsink), NULL);
g_mutex_lock (appsink->mutex);
while (TRUE) {
GST_DEBUG_OBJECT (appsink, "trying to grab a buffer");
if (!appsink->started)
goto not_started;
if (appsink->preroll != NULL)
break;
if (appsink->is_eos)
goto eos;
/* nothing to return, wait */
GST_DEBUG_OBJECT (appsink, "waiting for the preroll buffer");
g_cond_wait (appsink->cond, appsink->mutex);
}
buf = gst_buffer_ref (appsink->preroll);
GST_DEBUG_OBJECT (appsink, "we have the preroll buffer %p", buf);
g_mutex_unlock (appsink->mutex);
return buf;
/* special conditions */
eos:
{
GST_DEBUG_OBJECT (appsink, "we are EOS, return NULL");
g_mutex_unlock (appsink->mutex);
return NULL;
}
not_started:
{
GST_DEBUG_OBJECT (appsink, "we are stopped, return NULL");
g_mutex_unlock (appsink->mutex);
return NULL;
}
}
/**
* gst_app_sink_pull_buffer:
* @appsink: a #GstAppSink
*
* This function blocks until a buffer or EOS becomes available or the appsink
* element is set to the READY/NULL state.
*
* This function will only return buffers when the appsink is in the PLAYING
* state. All rendered buffers will be put in a queue so that the application
* can pull buffers at its own rate. Note that when the application does not
* pull buffers fast enough, the queued buffers could consume a lot of memory,
* especially when dealing with raw video frames.
*
* If an EOS event was received before any buffers, this function returns
* %NULL. Use gst_app_sink_is_eos () to check for the EOS condition.
*
* Returns: a #GstBuffer or NULL when the appsink is stopped or EOS.
*/
GstBuffer *
gst_app_sink_pull_buffer (GstAppSink * appsink)
{
GstBuffer *buf = NULL;
g_return_val_if_fail (appsink != NULL, NULL);
g_return_val_if_fail (GST_IS_APP_SINK (appsink), NULL);
g_mutex_lock (appsink->mutex);
while (TRUE) {
GST_DEBUG_OBJECT (appsink, "trying to grab a buffer");
if (!appsink->started)
goto not_started;
if (!g_queue_is_empty (appsink->queue))
break;
if (appsink->is_eos)
goto eos;
/* nothing to return, wait */
GST_DEBUG_OBJECT (appsink, "waiting for a buffer");
g_cond_wait (appsink->cond, appsink->mutex);
}
buf = g_queue_pop_head (appsink->queue);
GST_DEBUG_OBJECT (appsink, "we have a buffer %p", buf);
g_cond_signal (appsink->cond);
g_mutex_unlock (appsink->mutex);
return buf;
/* special conditions */
eos:
{
GST_DEBUG_OBJECT (appsink, "we are EOS, return NULL");
g_mutex_unlock (appsink->mutex);
return NULL;
}
not_started:
{
GST_DEBUG_OBJECT (appsink, "we are stopped, return NULL");
g_mutex_unlock (appsink->mutex);
return NULL;
}
}