[melted] / src / modules / core / producer_noise.c

/*
 * producer_noise.c -- noise generating producer
 * 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 "producer_noise.h"
#include <framework/mlt_frame.h>
#include <framework/mlt_pool.h>

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

/** Random number generator
*/

static unsigned int seed_x = 521288629;
static unsigned int seed_y = 362436069;

static unsigned inline int fast_rand( )
{
   static unsigned int a = 18000, b = 30903;
   seed_x = a * ( seed_x & 65535 ) + ( seed_x >> 16 );
   seed_y = b * ( seed_y & 65535 ) + ( seed_y >> 16 );
   return ( ( seed_x << 16 ) + ( seed_y & 65535 ) );
}

// Foward declarations
static int producer_get_frame( mlt_producer this, mlt_frame_ptr frame, int index );

/** Initialise.
*/

mlt_producer producer_noise_init( void *arg )
{
        // Create a new producer object
        mlt_producer this = mlt_producer_new( );

        // Initialise the producer
        if ( this != NULL )
        {
                // Callback registration
                this->get_frame = producer_get_frame;
        }

        return this;
}

static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_format *format, int *width, int *height, int writable )
{
        // Obtain properties of frame
        mlt_properties properties = mlt_frame_properties( frame );

        // Calculate the size of the image
        int size = *width * *height * 2;

        // Set the format being returned
        *format = mlt_image_yuv422;

        // Allocate the image
        *buffer = mlt_pool_alloc( size );

        // Update the frame
        mlt_properties_set_data( properties, "image", *buffer, size, mlt_pool_release, NULL );
        mlt_properties_set_int( properties, "width", *width );
        mlt_properties_set_int( properties, "height", *height );

        // Before we write to the image, make sure we have one
        if ( *buffer != NULL )
        {
                // Calculate the end of the buffer
                uint8_t *p = *buffer + *width * *height * 2;

                // Value to hold a random number
                uint32_t value;

                // Generate random noise
                while ( p != *buffer )
                {
                        value = fast_rand( );
                        *( -- p ) = 128;
                        *( -- p ) = value & 0xff;
                        *( -- p ) = 128;
                        *( -- p ) = ( ( value & 0xff00 ) >> 8 ) & 0xf0;
                }
        }

        return 0;
}

static int producer_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
{
        // Get the frame properties
        mlt_properties properties = mlt_frame_properties( frame );

        int size = 0;

        // Correct the returns if necessary
        *samples = *samples <= 0 ? 1920 : *samples;
        *channels = *channels <= 0 ? 2 : *channels;
        *frequency = *frequency <= 0 ? 48000 : *frequency;

        // Calculate the size of the buffer
        size = *samples * *channels * sizeof( int16_t );

        // Allocate the buffer
        *buffer = mlt_pool_alloc( size );

        // Make sure we got one and fill it
        if ( *buffer != NULL )
        {
                int16_t *p = *buffer + size / 2;
                while ( p != *buffer ) 
                        *( -- p ) = fast_rand( ) & 0xff;
        }

        // Set the buffer for destruction
        mlt_properties_set_data( properties, "audio", *buffer, size, ( mlt_destructor )mlt_pool_release, NULL );

        return 0;
}

static int producer_get_frame( mlt_producer this, mlt_frame_ptr frame, int index )
{
        // Generate a frame
        *frame = mlt_frame_init( );

        // Check that we created a frame and initialise it
        if ( *frame != NULL )
        {
                // Obtain properties of frame
                mlt_properties properties = mlt_frame_properties( *frame );

                // Aspect ratio is 1?
                mlt_properties_set_double( properties, "aspect_ratio", 1.0 );

                // Set producer-specific frame properties
                mlt_properties_set_int( properties, "progressive", 1 );

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

                // Push the get_image method
                mlt_frame_push_get_image( *frame, producer_get_image );

                // Specify the audio
                ( *frame )->get_audio = producer_get_audio;
        }

        // Calculate the next timecode
        mlt_producer_prepare_next( this );

        return 0;
}