mlt_consumer.c: let consumers use read-ahead processing thread without frame dropping...

[melted] / src / framework / mlt_consumer.c

/*
 * mlt_consumer.c -- abstraction for all consumer services
 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
 * Author: Charles Yates <charles.yates@pandora.be>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser 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
 */

#include "mlt_consumer.h"
#include "mlt_factory.h"
#include "mlt_producer.h"
#include "mlt_frame.h"
#include "mlt_profile.h"

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/time.h>

static void mlt_consumer_frame_render( mlt_listener listener, mlt_properties owner, mlt_service this, void **args );
static void mlt_consumer_frame_show( mlt_listener listener, mlt_properties owner, mlt_service this, void **args );
static void mlt_consumer_property_changed( mlt_service owner, mlt_consumer this, char *name );
static void apply_profile_properties( mlt_consumer this, mlt_profile profile, mlt_properties properties );

/** Public final methods
*/

int mlt_consumer_init( mlt_consumer this, void *child, mlt_profile profile )
{
        int error = 0;
        memset( this, 0, sizeof( struct mlt_consumer_s ) );
        this->child = child;
        error = mlt_service_init( &this->parent, this );
        if ( error == 0 )
        {
                // Get the properties from the service
                mlt_properties properties = MLT_SERVICE_PROPERTIES( &this->parent );
        
                // Apply profile to properties
                if ( profile == NULL )
                {
                        // Normally the application creates the profile and controls its lifetime
                        // This is the fallback exception handling
                        profile = mlt_profile_init( NULL );
                        mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                        mlt_properties_set_data( properties, "_profile", profile, 0, (mlt_destructor)mlt_profile_close, NULL );
                }
                apply_profile_properties( this, profile, properties );

                // Default rescaler for all consumers
                mlt_properties_set( properties, "rescale", "bilinear" );

                // Default read ahead buffer size
                mlt_properties_set_int( properties, "buffer", 25 );

                // Default audio frequency and channels
                mlt_properties_set_int( properties, "frequency", 48000 );
                mlt_properties_set_int( properties, "channels", 2 );

                // Default of all consumers is real time
                mlt_properties_set_int( properties, "real_time", 1 );

                // Default to environment test card
                mlt_properties_set( properties, "test_card", mlt_environment( "MLT_TEST_CARD" ) );

                // Hmm - default all consumers to yuv422 :-/
                this->format = mlt_image_yuv422;

                mlt_events_register( properties, "consumer-frame-show", ( mlt_transmitter )mlt_consumer_frame_show );
                mlt_events_register( properties, "consumer-frame-render", ( mlt_transmitter )mlt_consumer_frame_render );
                mlt_events_register( properties, "consumer-stopped", NULL );

                // Register a property-changed listener to handle the profile property -
                // subsequent properties can override the profile
                this->event_listener = mlt_events_listen( properties, this, "property-changed", ( mlt_listener )mlt_consumer_property_changed );

                // Create the push mutex and condition
                pthread_mutex_init( &this->put_mutex, NULL );
                pthread_cond_init( &this->put_cond, NULL );

        }
        return error;
}

static void apply_profile_properties( mlt_consumer this, mlt_profile profile, mlt_properties properties )
{
        mlt_event_block( this->event_listener );
        mlt_properties_set_double( properties, "fps", mlt_profile_fps( profile ) );
        mlt_properties_set_int( properties, "frame_rate_num", profile->frame_rate_num );
        mlt_properties_set_int( properties, "frame_rate_den", profile->frame_rate_den );
        mlt_properties_set_int( properties, "width", profile->width );
        mlt_properties_set_int( properties, "height", profile->height );
        mlt_properties_set_int( properties, "progressive", profile->progressive );
        mlt_properties_set_double( properties, "aspect_ratio", mlt_profile_sar( profile )  );
        mlt_properties_set_int( properties, "sample_aspect_num", profile->sample_aspect_num );
        mlt_properties_set_int( properties, "sample_aspect_den", profile->sample_aspect_den );
        mlt_properties_set_double( properties, "display_ratio", mlt_profile_dar( profile )  );
        mlt_properties_set_int( properties, "display_aspect_num", profile->display_aspect_num );
        mlt_properties_set_int( properties, "display_aspect_num", profile->display_aspect_num );
        mlt_event_unblock( this->event_listener );
}

static void mlt_consumer_property_changed( mlt_service owner, mlt_consumer this, char *name )
{
        if ( !strcmp( name, "profile" ) )
        {
                // Get the properies
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );

                // Get the current profile
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );

                // Load the new profile
                mlt_profile new_profile = mlt_profile_init( mlt_properties_get( properties, name ) );

                if ( new_profile )
                {
                        // Copy the profile
                        if ( profile != NULL )
                        {
                                free( profile->description );
                                memcpy( profile, new_profile, sizeof( struct mlt_profile_s ) );
                                profile->description = strdup( new_profile->description );
                                mlt_profile_close( new_profile );
                        }
                        else
                        {
                                profile = new_profile;
                        }

                        // Apply to properties
                        apply_profile_properties( this, profile, properties );
                }
        }
        else if ( !strcmp( name, "frame_rate_num" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                if ( profile )
                {
                        profile->frame_rate_num = mlt_properties_get_int( properties, "frame_rate_num" );
                        mlt_properties_set_double( properties, "fps", mlt_profile_fps( profile ) );
                }
        }
        else if ( !strcmp( name, "frame_rate_den" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                if ( profile )
                {
                        profile->frame_rate_den = mlt_properties_get_int( properties, "frame_rate_den" );
                        mlt_properties_set_double( properties, "fps", mlt_profile_fps( profile ) );
                }
        }
        else if ( !strcmp( name, "width" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                if ( profile )
                        profile->width = mlt_properties_get_int( properties, "width" );
        }
        else if ( !strcmp( name, "height" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                if ( profile )
                        profile->height = mlt_properties_get_int( properties, "height" );
        }
        else if ( !strcmp( name, "progressive" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                if ( profile )
                        profile->progressive = mlt_properties_get_int( properties, "progressive" );
        }
        else if ( !strcmp( name, "sample_aspect_num" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                profile->sample_aspect_num = mlt_properties_get_int( properties, "sample_aspect_num" );
                if ( profile )
                        mlt_properties_set_double( properties, "aspect_ratio", mlt_profile_sar( profile )  );
        }
        else if ( !strcmp( name, "sample_aspect_den" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                profile->sample_aspect_den = mlt_properties_get_int( properties, "sample_aspect_den" );
                if ( profile )
                        mlt_properties_set_double( properties, "aspect_ratio", mlt_profile_sar( profile )  );
        }
        else if ( !strcmp( name, "display_aspect_num" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                if ( profile )
                {
                        profile->display_aspect_num = mlt_properties_get_int( properties, "display_aspect_num" );
                        mlt_properties_set_double( properties, "display_ratio", mlt_profile_dar( profile )  );
                }
        }
        else if ( !strcmp( name, "display_aspect_den" ) )
        {
                mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
                mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                if ( profile )
                {
                        profile->display_aspect_den = mlt_properties_get_int( properties, "display_aspect_den" );
                        mlt_properties_set_double( properties, "display_ratio", mlt_profile_dar( profile )  );
                }
        }
}

static void mlt_consumer_frame_show( mlt_listener listener, mlt_properties owner, mlt_service this, void **args )
{
        if ( listener != NULL )
                listener( owner, this, ( mlt_frame )args[ 0 ] );
}

static void mlt_consumer_frame_render( mlt_listener listener, mlt_properties owner, mlt_service this, void **args )
{
        if ( listener != NULL )
                listener( owner, this, ( mlt_frame )args[ 0 ] );
}

/** Create a new consumer.
*/

mlt_consumer mlt_consumer_new( mlt_profile profile )
{
        // Create the memory for the structure
        mlt_consumer this = malloc( sizeof( struct mlt_consumer_s ) );

        // Initialise it
        if ( this != NULL )
                mlt_consumer_init( this, NULL, profile );

        // Return it
        return this;
}

/** Get the parent service object.
*/

mlt_service mlt_consumer_service( mlt_consumer this )
{
        return this != NULL ? &this->parent : NULL;
}

/** Get the consumer properties.
*/

mlt_properties mlt_consumer_properties( mlt_consumer this )
{
        return this != NULL ? MLT_SERVICE_PROPERTIES( &this->parent ) : NULL;
}

/** Connect the consumer to the producer.
*/

int mlt_consumer_connect( mlt_consumer this, mlt_service producer )
{
        return mlt_service_connect_producer( &this->parent, producer, 0 );
}

/** Start the consumer.
*/

int mlt_consumer_start( mlt_consumer this )
{
        // Stop listening to the property-changed event
        mlt_event_block( this->event_listener );

        // Get the properies
        mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );

        // Determine if there's a test card producer
        char *test_card = mlt_properties_get( properties, "test_card" );

        // Just to make sure nothing is hanging around...
        mlt_frame_close( this->put );
        this->put = NULL;
        this->put_active = 1;

        // Deal with it now.
        if ( test_card != NULL )
        {
                if ( mlt_properties_get_data( properties, "test_card_producer", NULL ) == NULL )
                {
                        // Create a test card producer
                        mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( this ) );
                        mlt_producer producer = mlt_factory_producer( profile, NULL, test_card );

                        // Do we have a producer
                        if ( producer != NULL )
                        {
                                // Test card should loop I guess...
                                mlt_properties_set( MLT_PRODUCER_PROPERTIES( producer ), "eof", "loop" );
                                //mlt_producer_set_speed( producer, 0 );
                                //mlt_producer_set_in_and_out( producer, 0, 0 );

                                // Set the test card on the consumer
                                mlt_properties_set_data( properties, "test_card_producer", producer, 0, ( mlt_destructor )mlt_producer_close, NULL );
                        }
                }
        }
        else
        {
                // Allow the hash table to speed things up
                mlt_properties_set_data( properties, "test_card_producer", NULL, 0, NULL, NULL );
        }

        // Check and run an ante command
        if ( mlt_properties_get( properties, "ante" ) )
                system( mlt_properties_get( properties, "ante" ) );

        // Set the real_time preference
        this->real_time = mlt_properties_get_int( properties, "real_time" );

        // Start the service
        if ( this->start != NULL )
                return this->start( this );

        return 0;
}

/** An alternative method to feed frames into the consumer - only valid if
        the consumer itself is not connected.
*/

int mlt_consumer_put_frame( mlt_consumer this, mlt_frame frame )
{
        int error = 1;

        // Get the service assoicated to the consumer
        mlt_service service = MLT_CONSUMER_SERVICE( this );

        if ( mlt_service_producer( service ) == NULL )
        {
                struct timeval now;
                struct timespec tm;
                pthread_mutex_lock( &this->put_mutex );
                while ( this->put_active && this->put != NULL )
                {
                        gettimeofday( &now, NULL );
                        tm.tv_sec = now.tv_sec + 1;
                        tm.tv_nsec = now.tv_usec * 1000;
                        pthread_cond_timedwait( &this->put_cond, &this->put_mutex, &tm );
                }
                if ( this->put_active && this->put == NULL )
                        this->put = frame;
                else
                        mlt_frame_close( frame );
                pthread_cond_broadcast( &this->put_cond );
                pthread_mutex_unlock( &this->put_mutex );
        }
        else
        {
                mlt_frame_close( frame );
        }

        return error;
}

/** Protected method for consumer to get frames from connected service
*/

mlt_frame mlt_consumer_get_frame( mlt_consumer this )
{
        // Frame to return
        mlt_frame frame = NULL;

        // Get the service assoicated to the consumer
        mlt_service service = MLT_CONSUMER_SERVICE( this );

        // Get the consumer properties
        mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );

        // Get the frame
        if ( mlt_service_producer( service ) == NULL && mlt_properties_get_int( properties, "put_mode" ) )
        {
                struct timeval now;
                struct timespec tm;
                pthread_mutex_lock( &this->put_mutex );
                while ( this->put_active && this->put == NULL )
                {
                        gettimeofday( &now, NULL );
                        tm.tv_sec = now.tv_sec + 1;
                        tm.tv_nsec = now.tv_usec * 1000;
                        pthread_cond_timedwait( &this->put_cond, &this->put_mutex, &tm );
                }
                frame = this->put;
                this->put = NULL;
                pthread_cond_broadcast( &this->put_cond );
                pthread_mutex_unlock( &this->put_mutex );
                if ( frame != NULL )
                        mlt_service_apply_filters( service, frame, 0 );
        }
        else if ( mlt_service_producer( service ) != NULL )
        {
                mlt_service_get_frame( service, &frame, 0 );
        }
        else
        {
                frame = mlt_frame_init( service );
        }

        if ( frame != NULL )
        {
                // Get the frame properties
                mlt_properties frame_properties = MLT_FRAME_PROPERTIES( frame );

                // Get the test card producer
                mlt_producer test_card = mlt_properties_get_data( properties, "test_card_producer", NULL );

                // Attach the test frame producer to it.
                if ( test_card != NULL )
                        mlt_properties_set_data( frame_properties, "test_card_producer", test_card, 0, NULL, NULL );

                // Attach the rescale property
                mlt_properties_set( frame_properties, "rescale.interp", mlt_properties_get( properties, "rescale" ) );

                // Aspect ratio and other jiggery pokery
                mlt_properties_set_double( frame_properties, "consumer_aspect_ratio", mlt_properties_get_double( properties, "aspect_ratio" ) );
                mlt_properties_set_int( frame_properties, "consumer_deinterlace", mlt_properties_get_int( properties, "progressive" ) | mlt_properties_get_int( properties, "deinterlace" ) );
                mlt_properties_set( frame_properties, "deinterlace_method", mlt_properties_get( properties, "deinterlace_method" ) );
        }

        // Return the frame
        return frame;
}

static inline long time_difference( struct timeval *time1 )
{
        struct timeval time2;
        time2.tv_sec = time1->tv_sec;
        time2.tv_usec = time1->tv_usec;
        gettimeofday( time1, NULL );
        return time1->tv_sec * 1000000 + time1->tv_usec - time2.tv_sec * 1000000 - time2.tv_usec;
}

static void *consumer_read_ahead_thread( void *arg )
{
        // The argument is the consumer
        mlt_consumer this = arg;

        // Get the properties of the consumer
        mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );

        // Get the width and height
        int width = mlt_properties_get_int( properties, "width" );
        int height = mlt_properties_get_int( properties, "height" );

        // See if video is turned off
        int video_off = mlt_properties_get_int( properties, "video_off" );
        int preview_off = mlt_properties_get_int( properties, "preview_off" );
        int preview_format = mlt_properties_get_int( properties, "preview_format" );

        // Get the audio settings
        mlt_audio_format afmt = mlt_audio_pcm;
        int counter = 0;
        double fps = mlt_properties_get_double( properties, "fps" );
        int channels = mlt_properties_get_int( properties, "channels" );
        int frequency = mlt_properties_get_int( properties, "frequency" );
        int samples = 0;
        int16_t *pcm = NULL;

        // See if audio is turned off
        int audio_off = mlt_properties_get_int( properties, "audio_off" );

        // Get the maximum size of the buffer
        int buffer = mlt_properties_get_int( properties, "buffer" ) + 1;

        // General frame variable
        mlt_frame frame = NULL;
        uint8_t *image = NULL;

        // Time structures
        struct timeval ante;

        // Average time for get_frame and get_image
        int count = 1;
        int skipped = 0;
        int64_t time_wait = 0;
        int64_t time_frame = 0;
        int64_t time_process = 0;
        int skip_next = 0;
        mlt_service lock_object = NULL;

        if ( preview_off && preview_format != 0 )
                this->format = preview_format;

        // Get the first frame
        frame = mlt_consumer_get_frame( this );

        // Get the lock object
        lock_object = mlt_properties_get_data( MLT_FRAME_PROPERTIES( frame ), "consumer_lock_service", NULL );

        // Lock it
        if ( lock_object ) mlt_service_lock( lock_object );

        // Get the image of the first frame
        if ( !video_off )
        {
                mlt_events_fire( MLT_CONSUMER_PROPERTIES( this ), "consumer-frame-render", frame, NULL );
                mlt_frame_get_image( frame, &image, &this->format, &width, &height, 0 );
        }

        if ( !audio_off )
        {
                samples = mlt_sample_calculator( fps, frequency, counter++ );
                mlt_frame_get_audio( frame, &pcm, &afmt, &frequency, &channels, &samples );
        }

        // Unlock the lock object
        if ( lock_object ) mlt_service_unlock( lock_object );

        // Mark as rendered
        mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );

        // Get the starting time (can ignore the times above)
        gettimeofday( &ante, NULL );

        // Continue to read ahead
        while ( this->ahead )
        {
                // Fetch width/height again
                width = mlt_properties_get_int( properties, "width" );
                height = mlt_properties_get_int( properties, "height" );

                // Put the current frame into the queue
                pthread_mutex_lock( &this->mutex );
                while( this->ahead && mlt_deque_count( this->queue ) >= buffer )
                        pthread_cond_wait( &this->cond, &this->mutex );
                mlt_deque_push_back( this->queue, frame );
                pthread_cond_broadcast( &this->cond );
                pthread_mutex_unlock( &this->mutex );

                time_wait += time_difference( &ante );

                // Get the next frame
                frame = mlt_consumer_get_frame( this );
                time_frame += time_difference( &ante );

                // If there's no frame, we're probably stopped...
                if ( frame == NULL )
                        continue;

                // Attempt to fetch the lock object
                lock_object = mlt_properties_get_data( MLT_FRAME_PROPERTIES( frame ), "consumer_lock_service", NULL );

                // Increment the count
                count ++;

                // Lock if there's a lock object
                if ( lock_object ) mlt_service_lock( lock_object );

                // All non normal playback frames should be shown
                if ( mlt_properties_get_int( MLT_FRAME_PROPERTIES( frame ), "_speed" ) != 1 )
                {
                        mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "consumer_deinterlace", 1 );
                        skipped = 0;
                        time_frame = 0;
                        time_process = 0;
                        time_wait = 0;
                        count = 1;
                        skip_next = 0;
                }

                // Get the image
                if ( !skip_next || this->real_time == -1 )
                {
                        // Get the image, mark as rendered and time it
                        if ( !video_off )
                        {
                                mlt_events_fire( MLT_CONSUMER_PROPERTIES( this ), "consumer-frame-render", frame, NULL );
                                mlt_frame_get_image( frame, &image, &this->format, &width, &height, 0 );
                        }
                        mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );
                }
                else
                {
                        // Increment the number of sequentially skipped frames
                        skipped ++;
                        skip_next = 0;

                        // If we've reached an unacceptable level, reset everything
                        if ( skipped > 5 )
                        {
                                skipped = 0;
                                time_frame = 0;
                                time_process = 0;
                                time_wait = 0;
                                count = 1;
                        }
                }

                // Always process audio
                if ( !audio_off )
                {
                        samples = mlt_sample_calculator( fps, frequency, counter++ );
                        mlt_frame_get_audio( frame, &pcm, &afmt, &frequency, &channels, &samples );
                }

                // Increment the time take for this frame
                time_process += time_difference( &ante );

                // Determine if the next frame should be skipped
                if ( mlt_deque_count( this->queue ) <= 5 && ( ( time_wait + time_frame + time_process ) / count ) > 40000 )
                        skip_next = 1;

                // Unlock if there's a lock object
                if ( lock_object ) mlt_service_unlock( lock_object );
        }

        // Remove the last frame
        mlt_frame_close( frame );

        return NULL;
}

static void consumer_read_ahead_start( mlt_consumer this )
{
        // We're running now
        this->ahead = 1;

        // Create the frame queue
        this->queue = mlt_deque_init( );

        // Create the mutex
        pthread_mutex_init( &this->mutex, NULL );

        // Create the condition
        pthread_cond_init( &this->cond, NULL );

        // Create the read ahead 
        pthread_create( &this->ahead_thread, NULL, consumer_read_ahead_thread, this );
}

static void consumer_read_ahead_stop( mlt_consumer this )
{
        // Make sure we're running
        if ( this->ahead )
        {
                // Inform thread to stop
                this->ahead = 0;

                // Broadcast to the condition in case it's waiting
                pthread_mutex_lock( &this->mutex );
                pthread_cond_broadcast( &this->cond );
                pthread_mutex_unlock( &this->mutex );

                // Broadcast to the put condition in case it's waiting
                pthread_mutex_lock( &this->put_mutex );
                pthread_cond_broadcast( &this->put_cond );
                pthread_mutex_unlock( &this->put_mutex );

                // Join the thread
                pthread_join( this->ahead_thread, NULL );

                // Destroy the mutex
                pthread_mutex_destroy( &this->mutex );

                // Destroy the condition
                pthread_cond_destroy( &this->cond );

                // Wipe the queue
                while ( mlt_deque_count( this->queue ) )
                        mlt_frame_close( mlt_deque_pop_back( this->queue ) );

                // Close the queue
                mlt_deque_close( this->queue );
        }
}

void mlt_consumer_purge( mlt_consumer this )
{
        if ( this->ahead )
        {
                pthread_mutex_lock( &this->mutex );
                while ( mlt_deque_count( this->queue ) )
                        mlt_frame_close( mlt_deque_pop_back( this->queue ) );
                pthread_cond_broadcast( &this->cond );
                pthread_mutex_unlock( &this->mutex );
        }
}

mlt_frame mlt_consumer_rt_frame( mlt_consumer this )
{
        // Frame to return
        mlt_frame frame = NULL;

        // Get the properties
        mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );

        // Check if the user has requested real time or not
        if ( this->real_time )
        {
                int size = 1;

                // Is the read ahead running?
                if ( this->ahead == 0 )
                {
                        int buffer = mlt_properties_get_int( properties, "buffer" );
                        int prefill = mlt_properties_get_int( properties, "prefill" );
                        consumer_read_ahead_start( this );
                        if ( buffer > 1 )
                                size = prefill > 0 && prefill < buffer ? prefill : buffer;
                }
        
                // Get frame from queue
                pthread_mutex_lock( &this->mutex );
                while( this->ahead && mlt_deque_count( this->queue ) < size )
                        pthread_cond_wait( &this->cond, &this->mutex );
                frame = mlt_deque_pop_front( this->queue );
                pthread_cond_broadcast( &this->cond );
                pthread_mutex_unlock( &this->mutex );
        }
        else
        {
                // Get the frame in non real time
                frame = mlt_consumer_get_frame( this );

                // This isn't true, but from the consumers perspective it is
                if ( frame != NULL )
                        mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );
        }

        return frame;
}

/** Callback for the implementation to indicate a stopped condition.
*/

void mlt_consumer_stopped( mlt_consumer this )
{
        mlt_properties_set_int( MLT_CONSUMER_PROPERTIES( this ), "running", 0 );
        mlt_events_fire( MLT_CONSUMER_PROPERTIES( this ), "consumer-stopped", NULL );
        mlt_event_unblock( this->event_listener );
}

/** Stop the consumer.
*/

int mlt_consumer_stop( mlt_consumer this )
{
        // Get the properies
        mlt_properties properties = MLT_CONSUMER_PROPERTIES( this );
        char *debug = mlt_properties_get( MLT_CONSUMER_PROPERTIES( this ), "debug" );

        // Just in case...
        if ( debug ) fprintf( stderr, "%s: stopping put waiting\n", debug );
        pthread_mutex_lock( &this->put_mutex );
        this->put_active = 0;
        pthread_cond_broadcast( &this->put_cond );
        pthread_mutex_unlock( &this->put_mutex );

        // Stop the consumer
        if ( debug ) fprintf( stderr, "%s: stopping consumer\n", debug );
        if ( this->stop != NULL )
                this->stop( this );

        // Check if the user has requested real time or not and stop if necessary
        if ( debug ) fprintf( stderr, "%s: stopping read_ahead\n", debug );
        if ( mlt_properties_get_int( properties, "real_time" ) )
                consumer_read_ahead_stop( this );

        // Kill the test card
        mlt_properties_set_data( properties, "test_card_producer", NULL, 0, NULL, NULL );

        // Check and run a post command
        if ( mlt_properties_get( properties, "post" ) )
                system( mlt_properties_get( properties, "post" ) );

        if ( debug ) fprintf( stderr, "%s: stopped\n", debug );

        return 0;
}

/** Determine if the consumer is stopped.
*/

int mlt_consumer_is_stopped( mlt_consumer this )
{
        // Check if the consumer is stopped
        if ( this->is_stopped != NULL )
                return this->is_stopped( this );

        return 0;
}

/** Close the consumer.
*/

void mlt_consumer_close( mlt_consumer this )
{
        if ( this != NULL && mlt_properties_dec_ref( MLT_CONSUMER_PROPERTIES( this ) ) <= 0 )
        {
                // Get the childs close function
                void ( *consumer_close )( ) = this->close;

                if ( consumer_close )
                {
                        // Just in case...
                        //mlt_consumer_stop( this );

                        this->close = NULL;
                        consumer_close( this );
                }
                else
                {
                        // Make sure it only gets called once
                        this->parent.close = NULL;

                        // Destroy the push mutex and condition
                        pthread_mutex_destroy( &this->put_mutex );
                        pthread_cond_destroy( &this->put_cond );

                        mlt_service_close( &this->parent );
                }
        }
}