Multitrack class. More...

#include <mlt_multitrack.h>

Inheritance diagram for mlt_multitrack_s:

Public Member Functions
mlt_position	mlt_multitrack_clip (mlt_multitrack self, mlt_whence whence, int index)
	Determine the clip point.
void	mlt_multitrack_close (mlt_multitrack self)
	Close this instance and free its resources.
int	mlt_multitrack_connect (mlt_multitrack self, mlt_producer producer, int track)
	Connect a producer to a given track.
int	mlt_multitrack_count (mlt_multitrack self)
	Get the number of tracks.
mlt_multitrack	mlt_multitrack_init ()
	Construct and initialize a new multitrack.
mlt_producer	mlt_multitrack_producer (mlt_multitrack self)
	Get the producer associated to this multitrack.
mlt_properties	mlt_multitrack_properties (mlt_multitrack self)
	Get the properties associated this multitrack.
void	mlt_multitrack_refresh (mlt_multitrack self)
	Initialize position related information.
mlt_service	mlt_multitrack_service (mlt_multitrack self)
	Get the service associated this multitrack.
mlt_producer	mlt_multitrack_track (mlt_multitrack self, int track)
	Get an individual track as a producer.
Data Fields
int	count
mlt_track *	list
struct mlt_producer_s	parent
	We're extending producer here.
int	size
Private Member Functions
static int	add_unique (mlt_position *array, int size, mlt_position position)
	Add a position to a set.
static void	mlt_multitrack_listener (mlt_producer producer, mlt_multitrack self)
	Listener for producers on the playlist.
static int	position_compare (const void p1, const void p2)
	Position comparison function for sorting.
static int	producer_get_frame (mlt_producer parent, mlt_frame_ptr frame, int index)
	Get frame method.

Detailed Description

Multitrack class.

A multitrack is a parallel container of producers that acts a single producer.

Property:: log_id not currently used, but sets it to "mulitrack"

Member Function Documentation

static int add_unique	(	mlt_position *	array,
		int	size,
		mlt_position	position
	)		`[private]`

Add a position to a set.

Parameters:

array	an array of positions (the set)
size	the current number of positions in the array (not the capacity of the array)
position	the position to add

Returns:: the new size of the array

mlt_position mlt_multitrack_clip	(	mlt_multitrack	self,
		mlt_whence	whence,
		int	index
	)

Determine the clip point.

 Special case here: a 'producer' has no concept of multiple clips - only the
 playlist and multitrack producers have clip functionality. Further to that a
 multitrack determines clip information from any connected tracks that happen
 to be playlists.

 Additionally, it must locate clips in the correct order, for example, consider
 the following track arrangement:

 playlist1 |0.0     |b0.0      |0.1          |0.1         |0.2           |
 playlist2 |b1.0  |1.0           |b1.1     |1.1             |

 Note - b clips represent blanks. They are also reported as clip positions.

 When extracting clip positions from these playlists, we should get a sequence of:

 0.0, 1.0, b0.0, 0.1, b1.1, 1.1, 0.1, 0.2, [out of playlist2], [out of playlist1]

Parameters:

self	a multitrack
whence	from where to extract
index	the 0-based index of which clip to extract

Returns:: the position of clip index relative to whence

void mlt_multitrack_close ( mlt_multitrack self )

Close this instance and free its resources.

Parameters:

self	a multitrack

int mlt_multitrack_connect	(	mlt_multitrack	self,
		mlt_producer	producer,
		int	track
	)

Connect a producer to a given track.

Note that any producer can be connected here, but see special case treatment of playlist in clip point determination below.

Parameters:

self	a multitrack
producer	the producer to connect to the multitrack producer
track	the 0-based index of the track on which to connect the multitrack

Returns:: true on error

int mlt_multitrack_count ( mlt_multitrack self )

Get the number of tracks.

Parameters:

self	a multitrack

Returns:: the number of tracks

mlt_multitrack mlt_multitrack_init ( )

Construct and initialize a new multitrack.

Sets the resource property to "<multitrack>".

Returns:: a new multitrack

static void mlt_multitrack_listener	(	mlt_producer	producer,
		mlt_multitrack	self
	)		`[private]`

Listener for producers on the playlist.

Parameters:

producer	a producer
self	a multitrack

mlt_producer mlt_multitrack_producer ( mlt_multitrack self )

Get the producer associated to this multitrack.

Parameters:

self	a multitrack

Returns:: the producer object

See also:: MLT_MULTITRACK_PRODUCER

mlt_properties mlt_multitrack_properties ( mlt_multitrack self )

Get the properties associated this multitrack.

Parameters:

self	a multitrack

Returns:: the multitrack's property list

See also:: MLT_MULTITRACK_PROPERTIES

void mlt_multitrack_refresh ( mlt_multitrack self )

Initialize position related information.

Parameters:

self	a multitrack

mlt_service mlt_multitrack_service ( mlt_multitrack self )

Get the service associated this multitrack.

Parameters:

self	a multitrack

Returns:: the service object

See also:: MLT_MULTITRACK_SERVICE

mlt_producer mlt_multitrack_track	(	mlt_multitrack	self,
		int	track
	)

Get an individual track as a producer.

Parameters:

self	a multitrack
track	the 0-based index of the producer to get

Returns:: the producer or NULL if not valid

static int position_compare	(	const void *	p1,
		const void *	p2
	)		`[private]`

Position comparison function for sorting.

Parameters:

p1	a position
p2	another position

Returns:: <0 if p1 is less than p2, 0 if equal, >0 if greater

static int producer_get_frame	(	mlt_producer	parent,
		mlt_frame_ptr	frame,
		int	track
	)		`[private]`

Get frame method.

Get the next frame.

Get the current frame.

 Special case here: The multitrack must be used in a conjunction with a downstream
 tractor-type service, ie:

 Producer1 \
 Producer2 - multitrack - { filters/transitions } - tractor - consumer
 Producer3 /

 The get_frame of a tractor pulls frames from it's connected service on all tracks and
 will terminate as soon as it receives a test card with a last_track property. The
 important case here is that the mulitrack does not move to the next frame until all
 tracks have been pulled.

 Reasoning: In order to seek on a network such as above, the multitrack needs to ensure
 that all producers are positioned on the same frame. It uses the 'last track' logic
 to determine when to move to the next frame.

 Flaw: if a transition is configured to read from a b-track which happens to trigger
 the last frame logic (ie: it's configured incorrectly), then things are going to go
 out of sync.