multitrack eof handling

[melted] / src / framework / mlt_multitrack.c

/*
 * mlt_multitrack.c -- multitrack service class
 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
 * Author: Charles Yates <charles.yates@pandora.be>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include "mlt_multitrack.h"
#include "mlt_playlist.h"
#include "mlt_frame.h"

#include <stdio.h>
#include <stdlib.h>

/** Private definition.
*/

struct mlt_multitrack_s
{
        // We're extending producer here
        struct mlt_producer_s parent;
        mlt_producer *list;
        int size;
        int count;
};

/** Forward reference.
*/

static int producer_get_frame( mlt_producer parent, mlt_frame_ptr frame, int index );

/** Constructor.
*/

mlt_multitrack mlt_multitrack_init( )
{
        // Allocate the multitrack object
        mlt_multitrack this = calloc( sizeof( struct mlt_multitrack_s ), 1 );

        if ( this != NULL )
        {
                mlt_producer producer = &this->parent;
                if ( mlt_producer_init( producer, this ) == 0 )
                {
                        mlt_properties properties = mlt_multitrack_properties( this );
                        producer->get_frame = producer_get_frame;
                        mlt_properties_set_data( properties, "multitrack", this, 0, NULL, NULL );
                        mlt_properties_set( properties, "log_id", "multitrack" );
                }
                else
                {
                        free( this );
                        this = NULL;
                }
        }
        
        return this;
}

/** Get the producer associated to this multitrack.
*/

mlt_producer mlt_multitrack_producer( mlt_multitrack this )
{
        return &this->parent;
}

/** Get the service associated this multitrack.
*/

mlt_service mlt_multitrack_service( mlt_multitrack this )
{
        return mlt_producer_service( mlt_multitrack_producer( this ) );
}

/** Get the properties associated this multitrack.
*/

mlt_properties mlt_multitrack_properties( mlt_multitrack this )
{
        return mlt_service_properties( mlt_multitrack_service( this ) );
}

/** Initialise timecode related information.
*/

void mlt_multitrack_refresh( mlt_multitrack this )
{
        int i = 0;

        // Obtain the properties of this multitrack
        mlt_properties properties = mlt_multitrack_properties( this );

        // We need to ensure that the multitrack reports the longest track as its length
        mlt_timecode length = 0;

        // We need to ensure that fps are the same on all services
        double fps = 0;
        
        // Obtain stats on all connected services
        for ( i = 0; i < this->count; i ++ )
        {
                // Get the producer from this index
                mlt_producer producer = this->list[ i ];

                // If it's allocated then, update our stats
                if ( producer != NULL )
                {
                        // If we have more than 1 track, we must be in continue mode
                        if ( this->count > 1 )
                                mlt_properties_set( mlt_producer_properties( producer ), "eof", "continue" );
                        
                        // Determine the longest length
                        length = mlt_producer_get_playtime( producer ) > length ? mlt_producer_get_playtime( producer ) : length;
                        
                        // Handle fps
                        if ( fps == 0 )
                        {
                                // This is the first producer, so it controls the fps
                                fps = mlt_producer_get_fps( producer );
                        }
                        else if ( fps != mlt_producer_get_fps( producer ) )
                        {
                                // Generate a warning for now - the following attempt to fix may fail
                                fprintf( stderr, "Warning: fps mismatch on track %d\n", i );

                                // It should be safe to impose fps on an image producer, but not necessarily safe for video
                                mlt_properties_set_double( mlt_producer_properties( producer ), "fps", fps );
                        }
                }
        }

        // Update multitrack properties now - we'll not destroy the in point here
        mlt_properties_set_timecode( properties, "length", length );
        mlt_properties_set_timecode( properties, "out", length );
        mlt_properties_set_double( properties, "fps", fps );
}

/** 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.
*/

int mlt_multitrack_connect( mlt_multitrack this, mlt_producer producer, int track )
{
        // Connect to the producer to ourselves at the specified track
        int result = mlt_service_connect_producer( mlt_multitrack_service( this ), mlt_producer_service( producer ), track );

        if ( result == 0 )
        {
                // Resize the producer list if need be
                if ( track >= this->size )
                {
                        int i;
                        this->list = realloc( this->list, ( track + 10 ) * sizeof( mlt_producer ) );
                        for ( i = this->size; i < track + 10; i ++ )
                                this->list[ i ] = NULL;
                        this->size = track + 10;
                }
                
                // Assign the track in our list here
                this->list[ track ] = producer;
                
                // Increment the track count if need be
                if ( track >= this->count )
                        this->count = track + 1;
                        
                // Refresh our stats
                mlt_multitrack_refresh( this );
        }

        return result;
}

/** 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]
*/

mlt_timecode mlt_multitrack_clip( mlt_multitrack this, mlt_whence whence, int index )
{
        int first = 1;
        mlt_timecode position = 0;
        int i = 0;

        // Loop through each of the tracks
        for ( i = 0; i < this->count; i ++ )
        {
                // Get the producer for this track
                mlt_producer producer = this->list[ i ];

                // If it's assigned...
                if ( producer != NULL )
                {
                        // Get the properties of this producer
                        mlt_properties properties = mlt_producer_properties( producer );

                        // Determine if it's a playlist
                        mlt_playlist playlist = mlt_properties_get_data( properties, "playlist", NULL );

                        // We only consider playlists
                        if ( playlist != NULL )
                        {
                                // Locate the smallest timecode
                                if ( first )
                                {
                                        // First position found
                                        position = mlt_playlist_clip( playlist, whence, index );
        
                                        // We're no longer first
                                        first = 0;
                                }
                                else
                                {
                                        // Obtain the clip position in this playlist
                                        mlt_timecode position2 = mlt_playlist_clip( playlist, whence, index );

                                        // If this position is prior to the first, then use it
                                        if ( position2 < position )
                                                position = position2;
                                }
                        }
                }
        }

        return position;
}

/** Get frame method.

        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.

        See playlist logic too.
*/

static int producer_get_frame( mlt_producer parent, mlt_frame_ptr frame, int index )
{
        // Get the mutiltrack object
        mlt_multitrack this = parent->child;

        // Check if we have a track for this index
        if ( index < this->count && this->list[ index ] != NULL )
        {
                // Get the producer for this track
                mlt_producer producer = this->list[ index ];

                // Obtain the current timecode
                uint64_t position = mlt_producer_frame( parent );

                // Make sure we're at the same point
                mlt_producer_seek_frame( producer, position );

                // Get the frame from the producer
                mlt_service_get_frame( mlt_producer_service( producer ), frame, 0 );

                // Indicate speed of this producer
                mlt_properties producer_properties = mlt_producer_properties( parent );
                double speed = mlt_properties_get_double( producer_properties, "speed" );
                mlt_properties properties = mlt_frame_properties( *frame );
                mlt_properties_set_double( properties, "speed", speed );
        }
        else
        {
                // Generate a test frame
                *frame = mlt_frame_init( );

                // Update timecode on the frame we're creating
                mlt_frame_set_timecode( *frame, mlt_producer_position( parent ) );

                // Move on to the next frame
                if ( index >= this->count )
                {
                        // Let tractor know if we've reached the end
                        mlt_properties_set_int( mlt_frame_properties( *frame ), "last_track", 1 );

                        // Move to the next frame
                        mlt_producer_prepare_next( parent );
                }

                // Refresh our stats
                mlt_multitrack_refresh( this );
        }

        return 0;
}

/** Close this instance.
*/

void mlt_multitrack_close( mlt_multitrack this )
{
        // Close the producer
        mlt_producer_close( &this->parent );

        // Free the list
        free( this->list );

        // Free the object
        free( this );
}