GstCollectPads

GstCollectPads — manages a set of pads that operate in collect mode

Synopsis

#include <gst/base/gstcollectpads.h>

struct              GstCollectPads;
struct              GstCollectData;
void                (*GstCollectDataDestroyNotify)      (GstCollectData *data);
GstFlowReturn       (*GstCollectPadsBufferFunction)     (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         GstBuffer *buffer,
                                                         gpointer user_data);
gint                (*GstCollectPadsCompareFunction)    (GstCollectPads *pads,
                                                         GstCollectData *data1,
                                                         GstClockTime timestamp1,
                                                         GstCollectData *data2,
                                                         GstClockTime timestamp2,
                                                         gpointer user_data);
gboolean            (*GstCollectPadsEventFunction)      (GstCollectPads *pads,
                                                         GstCollectData *pad,
                                                         GstEvent *event,
                                                         gpointer user_data);
GstFlowReturn       (*GstCollectPadsClipFunction)       (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         GstBuffer *inbuffer,
                                                         GstBuffer **outbuffer,
                                                         gpointer user_data);
GstFlowReturn       (*GstCollectPadsFunction)           (GstCollectPads *pads,
                                                         gpointer user_data);
enum                GstCollectPadsStateFlags;
#define             GST_COLLECT_PADS_STATE              (data)
#define             GST_COLLECT_PADS_STATE_IS_SET       (data,
                                                         flag)
#define             GST_COLLECT_PADS_STATE_SET          (data,
                                                         flag)
#define             GST_COLLECT_PADS_STATE_UNSET        (data,
                                                         flag)
#define             GST_COLLECT_PADS_GET_STREAM_LOCK    (pads)
#define             GST_COLLECT_PADS_STREAM_LOCK        (pads)
#define             GST_COLLECT_PADS_STREAM_UNLOCK      (pads)
GstCollectPads *    gst_collect_pads_new                (void);
GstCollectData *    gst_collect_pads_add_pad            (GstCollectPads *pads,
                                                         GstPad *pad,
                                                         guint size,
                                                         GstCollectDataDestroyNotify destroy_notify,
                                                         gboolean lock);
gboolean            gst_collect_pads_remove_pad         (GstCollectPads *pads,
                                                         GstPad *pad);
void                gst_collect_pads_start              (GstCollectPads *pads);
void                gst_collect_pads_stop               (GstCollectPads *pads);
guint               gst_collect_pads_available          (GstCollectPads *pads);
guint               gst_collect_pads_flush              (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         guint size);
GstBuffer *         gst_collect_pads_peek               (GstCollectPads *pads,
                                                         GstCollectData *data);
GstBuffer *         gst_collect_pads_pop                (GstCollectPads *pads,
                                                         GstCollectData *data);
GstBuffer *         gst_collect_pads_read_buffer        (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         guint size);
GstBuffer *         gst_collect_pads_take_buffer        (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         guint size);
void                gst_collect_pads_set_buffer_function
                                                        (GstCollectPads *pads,
                                                         GstCollectPadsBufferFunction func,
                                                         gpointer user_data);
void                gst_collect_pads_set_compare_function
                                                        (GstCollectPads *pads,
                                                         GstCollectPadsCompareFunction func,
                                                         gpointer user_data);
void                gst_collect_pads_set_event_function (GstCollectPads *pads,
                                                         GstCollectPadsEventFunction func,
                                                         gpointer user_data);
void                gst_collect_pads_set_clip_function  (GstCollectPads *pads,
                                                         GstCollectPadsClipFunction clipfunc,
                                                         gpointer user_data);
void                gst_collect_pads_set_flushing       (GstCollectPads *pads,
                                                         gboolean flushing);
void                gst_collect_pads_set_function       (GstCollectPads *pads,
                                                         GstCollectPadsFunction func,
                                                         gpointer user_data);
void                gst_collect_pads_set_waiting        (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         gboolean waiting);

Object Hierarchy

  GObject
   +----GInitiallyUnowned
         +----GstObject
               +----GstCollectPads

Description

Manages a set of pads that operate in collect mode. This means that control is given to the manager of this object when all pads have data.

Last reviewed on 2011-10-28 (0.10.36)

Details

struct GstCollectPads

struct GstCollectPads {
  GSList        *data;                  /* list of CollectData items */
};

Collectpads object.

GSList *data;

GList of GstCollectData managed by this GstCollectPads.

struct GstCollectData

struct GstCollectData {
  /* with STREAM_LOCK of @collect */
  GstCollectPads        *collect;
  GstPad                *pad;
  GstBuffer             *buffer;
  guint                  pos;
  GstSegment             segment;
};

Structure used by the collect_pads.

GstCollectPads *collect;

owner GstCollectPads

GstPad *pad;

GstPad managed by this data

GstBuffer *buffer;

currently queued buffer.

guint pos;

position in the buffer

GstSegment segment;

last segment received.

GstCollectDataDestroyNotify ()

void                (*GstCollectDataDestroyNotify)      (GstCollectData *data);

A function that will be called when the GstCollectData will be freed. It is passed the pointer to the structure and should free any custom memory and resources allocated for it.

data :

the GstCollectData that will be freed

GstCollectPadsBufferFunction ()

GstFlowReturn       (*GstCollectPadsBufferFunction)     (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         GstBuffer *buffer,
                                                         gpointer user_data);

A function that will be called when a (considered oldest) buffer can be muxed. If all pads have reached EOS, this function is called with NULL buffer and NULL data.

pads :

the GstCollectPads that trigered the callback

data :

the GstCollectData of pad that has received the buffer

buffer :

the GstBuffer. [transfer full]

user_data :

user data passed to gst_collect_pads_set_buffer_function()

Returns :

GST_FLOW_OK for success

GstCollectPadsCompareFunction ()

gint                (*GstCollectPadsCompareFunction)    (GstCollectPads *pads,
                                                         GstCollectData *data1,
                                                         GstClockTime timestamp1,
                                                         GstCollectData *data2,
                                                         GstClockTime timestamp2,
                                                         gpointer user_data);

A function for comparing two timestamps of buffers or newsegments collected on one pad.

pads :

the GstCollectPads that is comparing the timestamps

data1 :

the first GstCollectData

timestamp1 :

the first timestamp

data2 :

the second GstCollectData

timestamp2 :

the second timestamp

user_data :

user data passed to gst_collect_pads_set_compare_function()

Returns :

Integer less than zero when first timestamp is deemed older than the second one. Zero if the timestamps are deemed equally old. Integer greate than zero when second timestamp is deemed older than the first one.

GstCollectPadsEventFunction ()

gboolean            (*GstCollectPadsEventFunction)      (GstCollectPads *pads,
                                                         GstCollectData *pad,
                                                         GstEvent *event,
                                                         gpointer user_data);

A function that will be called while processing an event. It takes ownership of the event and is responsible for chaining up (to gst_collect_pads_event_default()) or dropping events (such typical cases being handled by the default handler).

pads :

the GstCollectPads that trigered the callback

pad :

the GstPad that received an event

event :

the GstEvent received

user_data :

user data passed to gst_collect_pads_set_event_function()

Returns :

TRUE if the pad could handle the event

GstCollectPadsClipFunction ()

GstFlowReturn       (*GstCollectPadsClipFunction)       (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         GstBuffer *inbuffer,
                                                         GstBuffer **outbuffer,
                                                         gpointer user_data);

A function that will be called when inbuffer is received on the pad managed by data in the collecpad object pads.

The function should use the segment of data and the negotiated media type on the pad to perform clipping of inbuffer.

This function takes ownership of inbuffer and should output a buffer in outbuffer or return NULL in outbuffer if the buffer should be dropped.

pads :

a GstCollectPads

data :

a GstCollectData

inbuffer :

the input GstBuffer. [transfer full]

outbuffer :

the output GstBuffer

user_data :

user data

Returns :

a GstFlowReturn that corresponds to the result of clipping.

GstCollectPadsFunction ()

GstFlowReturn       (*GstCollectPadsFunction)           (GstCollectPads *pads,
                                                         gpointer user_data);

A function that will be called when all pads have received data.

pads :

the GstCollectPads that trigered the callback

user_data :

user data passed to gst_collect_pads_set_function()

Returns :

GST_FLOW_OK for success

enum GstCollectPadsStateFlags

typedef enum {
  GST_COLLECT_PADS_STATE_EOS = 1 << 0,
  GST_COLLECT_PADS_STATE_FLUSHING = 1 << 1,
  GST_COLLECT_PADS_STATE_NEW_SEGMENT = 1 << 2,
  GST_COLLECT_PADS_STATE_WAITING = 1 << 3,
  GST_COLLECT_PADS_STATE_LOCKED = 1 << 4
} GstCollectPadsStateFlags;

GST_COLLECT_PADS_STATE_EOS

Set if collectdata's pad is EOS.

GST_COLLECT_PADS_STATE_FLUSHING

Set if collectdata's pad is flushing.

GST_COLLECT_PADS_STATE_NEW_SEGMENT

Set if collectdata's pad received a new_segment event.

GST_COLLECT_PADS_STATE_WAITING

Set if collectdata's pad must be waited for when collecting.

GST_COLLECT_PADS_STATE_LOCKED

Set collectdata's pad WAITING state must not be changed. GstCollectPadsStateFlags indicate private state of a collectdata('s pad).

GST_COLLECT_PADS_STATE()

#define GST_COLLECT_PADS_STATE(data)                 (((GstCollectData *) data)->state)

A flags word containing GstCollectPadsStateFlags flags set on this collected pad.

data :

a GstCollectData.

GST_COLLECT_PADS_STATE_IS_SET()

#define GST_COLLECT_PADS_STATE_IS_SET(data,flag)     !!(GST_COLLECT_PADS_STATE (data) & flag)

Gives the status of a specific flag on a collected pad.

data :

a GstCollectData.

flag :

the GstCollectPadsStateFlags to check.

GST_COLLECT_PADS_STATE_SET()

#define GST_COLLECT_PADS_STATE_SET(data,flag)        (GST_COLLECT_PADS_STATE (data) |= flag)

Sets a state flag on a collected pad.

data :

a GstCollectData.

flag :

the GstCollectPadsStateFlags to set.

GST_COLLECT_PADS_STATE_UNSET()

#define GST_COLLECT_PADS_STATE_UNSET(data,flag)      (GST_COLLECT_PADS_STATE (data) &= ~(flag))

Clears a state flag on a collected pad.

data :

a GstCollectData.

flag :

the GstCollectPadsStateFlags to clear.

GST_COLLECT_PADS_GET_STREAM_LOCK()

#define GST_COLLECT_PADS_GET_STREAM_LOCK(pads) (&((GstCollectPads *)pads)->stream_lock)

Get the stream lock of pads. The stream lock is used to coordinate and serialize execution among the various streams being collected, and in protecting the resources used to accomplish this.

pads :

a GstCollectPads

GST_COLLECT_PADS_STREAM_LOCK()

#define GST_COLLECT_PADS_STREAM_LOCK(pads)     g_rec_mutex_lock(GST_COLLECT_PADS_GET_STREAM_LOCK (pads))

Lock the stream lock of pads.

pads :

a GstCollectPads

GST_COLLECT_PADS_STREAM_UNLOCK()

#define GST_COLLECT_PADS_STREAM_UNLOCK(pads)   g_rec_mutex_unlock(GST_COLLECT_PADS_GET_STREAM_LOCK (pads))

Unlock the stream lock of pads.

pads :

a GstCollectPads

gst_collect_pads_new ()

GstCollectPads *    gst_collect_pads_new                (void);

Create a new instance of GstCollectPads.

MT safe.

Returns :

a new GstCollectPads, or NULL in case of an error. [transfer full]

gst_collect_pads_add_pad ()

GstCollectData *    gst_collect_pads_add_pad            (GstCollectPads *pads,
                                                         GstPad *pad,
                                                         guint size,
                                                         GstCollectDataDestroyNotify destroy_notify,
                                                         gboolean lock);

Add a pad to the collection of collect pads. The pad has to be a sinkpad. The refcount of the pad is incremented. Use gst_collect_pads_remove_pad() to remove the pad from the collection again.

You specify a size for the returned GstCollectData structure so that you can use it to store additional information.

You can also specify a GstCollectDataDestroyNotify that will be called just before the GstCollectData structure is freed. It is passed the pointer to the structure and should free any custom memory and resources allocated for it.

Keeping a pad locked in waiting state is only relevant when using the default collection algorithm (providing the oldest buffer). It ensures a buffer must be available on this pad for a collection to take place. This is of typical use to a muxer element where non-subtitle streams should always be in waiting state, e.g. to assure that caps information is available on all these streams when initial headers have to be written.

The pad will be automatically activated in push mode when pads is started.

MT safe.

pads :

the collectpads to use

pad :

the pad to add. [transfer none]

size :

the size of the returned GstCollectData structure

destroy_notify :

function to be called before the returned GstCollectData structure is freed

lock :

whether to lock this pad in usual waiting state

Returns :

a new GstCollectData to identify the new pad. Or NULL if wrong parameters are supplied.

gst_collect_pads_remove_pad ()

gboolean            gst_collect_pads_remove_pad         (GstCollectPads *pads,
                                                         GstPad *pad);

Remove a pad from the collection of collect pads. This function will also free the GstCollectData and all the resources that were allocated with gst_collect_pads_add_pad().

The pad will be deactivated automatically when pads is stopped.

MT safe.

pads :

the collectpads to use

pad :

the pad to remove. [transfer none]

Returns :

TRUE if the pad could be removed.

gst_collect_pads_start ()

void                gst_collect_pads_start              (GstCollectPads *pads);

Starts the processing of data in the collect_pads.

MT safe.

pads :

the collectpads to use

gst_collect_pads_stop ()

void                gst_collect_pads_stop               (GstCollectPads *pads);

Stops the processing of data in the collect_pads. this function will also unblock any blocking operations.

MT safe.

pads :

the collectpads to use

gst_collect_pads_available ()

guint               gst_collect_pads_available          (GstCollectPads *pads);

Query how much bytes can be read from each queued buffer. This means that the result of this call is the maximum number of bytes that can be read from each of the pads.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

pads :

the collectpads to query

Returns :

The maximum number of bytes queued on all pads. This function returns 0 if a pad has no queued buffer.

gst_collect_pads_flush ()

guint               gst_collect_pads_flush              (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         guint size);

Flush size bytes from the pad data.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

pads :

the collectpads to query

data :

the data to use

size :

the number of bytes to flush

Returns :

The number of bytes flushed This can be less than size and is 0 if the pad was end-of-stream.

gst_collect_pads_peek ()

GstBuffer *         gst_collect_pads_peek               (GstCollectPads *pads,
                                                         GstCollectData *data);

Peek at the buffer currently queued in data. This function should be called with the pads STREAM_LOCK held, such as in the callback handler.

MT safe.

pads :

the collectpads to peek

data :

the data to use

Returns :

The buffer in data or NULL if no buffer is queued. should unref the buffer after usage.

gst_collect_pads_pop ()

GstBuffer *         gst_collect_pads_pop                (GstCollectPads *pads,
                                                         GstCollectData *data);

Pop the buffer currently queued in data. This function should be called with the pads STREAM_LOCK held, such as in the callback handler.

MT safe.

pads :

the collectpads to pop

data :

the data to use

Returns :

The buffer in data or NULL if no buffer was queued. You should unref the buffer after usage. [transfer full]

gst_collect_pads_read_buffer ()

GstBuffer *         gst_collect_pads_read_buffer        (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         guint size);

Get a subbuffer of size bytes from the given pad data.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

pads :

the collectpads to query

data :

the data to use

size :

the number of bytes to read

Returns :

A sub buffer. The size of the buffer can be less that requested. A return of NULL signals that the pad is end-of-stream. Unref the buffer after use. [transfer full]

gst_collect_pads_take_buffer ()

GstBuffer *         gst_collect_pads_take_buffer        (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         guint size);

Get a subbuffer of size bytes from the given pad data. Flushes the amount of read bytes.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

pads :

the collectpads to query

data :

the data to use

size :

the number of bytes to read

Returns :

A sub buffer. The size of the buffer can be less that requested. A return of NULL signals that the pad is end-of-stream. Unref the buffer after use.

gst_collect_pads_set_buffer_function ()

void                gst_collect_pads_set_buffer_function
                                                        (GstCollectPads *pads,
                                                         GstCollectPadsBufferFunction func,
                                                         gpointer user_data);

Set the callback function and user data that will be called with the oldest buffer when all pads have been collected, or NULL on EOS. If a buffer is passed, the callback owns a reference and must unref it.

MT safe.

pads :

the collectpads to use

func :

the function to set

user_data :

user data passed to the function. [closure]

gst_collect_pads_set_compare_function ()

void                gst_collect_pads_set_compare_function
                                                        (GstCollectPads *pads,
                                                         GstCollectPadsCompareFunction func,
                                                         gpointer user_data);

Set the timestamp comparison function.

MT safe.

pads :

the pads to use

func :

the function to set

user_data :

user data passed to the function. [closure]

gst_collect_pads_set_event_function ()

void                gst_collect_pads_set_event_function (GstCollectPads *pads,
                                                         GstCollectPadsEventFunction func,
                                                         gpointer user_data);

Set the event callback function and user data that will be called when collectpads has received an event originating from one of the collected pads. If the event being processed is a serialized one, this callback is called with pads STREAM_LOCK held, otherwise not. As this lock should be held when calling a number of CollectPads functions, it should be acquired if so (unusually) needed.

MT safe.

pads :

the collectpads to use

func :

the function to set

user_data :

user data passed to the function

gst_collect_pads_set_clip_function ()

void                gst_collect_pads_set_clip_function  (GstCollectPads *pads,
                                                         GstCollectPadsClipFunction clipfunc,
                                                         gpointer user_data);

Install a clipping function that is called right after a buffer is received on a pad managed by pads. See GstCollectPadsClipFunction for more info.

pads :

the collectpads to use

clipfunc :

clip function to install

user_data :

user data to pass to clip_func

gst_collect_pads_set_flushing ()

void                gst_collect_pads_set_flushing       (GstCollectPads *pads,
                                                         gboolean flushing);

Change the flushing state of all the pads in the collection. No pad is able to accept anymore data when flushing is TRUE. Calling this function with flushing FALSE makes pads accept data again. Caller must ensure that downstream streaming (thread) is not blocked, e.g. by sending a FLUSH_START downstream.

MT safe.

pads :

the collectpads to use

flushing :

desired state of the pads

gst_collect_pads_set_function ()

void                gst_collect_pads_set_function       (GstCollectPads *pads,
                                                         GstCollectPadsFunction func,
                                                         gpointer user_data);

CollectPads provides a default collection algorithm that will determine the oldest buffer available on all of its pads, and then delegate to a configured callback. However, if circumstances are more complicated and/or more control is desired, this sets a callback that will be invoked instead when all the pads added to the collection have buffers queued. Evidently, this callback is not compatible with gst_collect_pads_set_buffer_function() callback. If this callback is set, the former will be unset.

MT safe.

pads :

the collectpads to use

func :

the function to set

user_data :

user data passed to the function

gst_collect_pads_set_waiting ()

void                gst_collect_pads_set_waiting        (GstCollectPads *pads,
                                                         GstCollectData *data,
                                                         gboolean waiting);

Sets a pad to waiting or non-waiting mode, if at least this pad has not been created with locked waiting state, in which case nothing happens.

This function should be called with pads STREAM_LOCK held, such as in the callback.

MT safe.

pads :

the collectpads

data :

the data to use

waiting :

boolean indicating whether this pad should operate in waiting or non-waiting mode