Memory Playback local_memory_playback.c shows how to configure and use handle the Local Memory Playback feature.

/*=================================================================================
Local Memory Playback
This is a VAPI based code implementation of a function which can be used to play
announcement using the Local Memory Playback feature of the MSP.
=================================================================================*/
#include <stdio.h>
#include <vapi.h>
#include <msp.h>
#include <ut.h>

/*=================================================================================*/
/*=================================================================================*/
VSTATUS start_playback_buffer(unsigned int conn_id,
                                unsigned int fileid,
                                unsigned int side,
                                unsigned int time_to_play,
                                unsigned int completion_ind)
{
        VSTATUS result;

        void *message;
        U32 response_len = DEFAULT_FIFO_MAX_SIZE;
        U8 device_response [DEFAULT_FIFO_MAX_SIZE];

        /* allocate a message to query the current VCEOPT */
        message = VAPI_AllocateMessage(DEFAULT_FIFO_MAX_SIZE);
        if (message == NULL)
                return -1;

        /*If not both sides, play to the required side*/
        if (side != 2)
                result = VAPI_SetMessage(message , CMD_CLASS_CONF_CHANNEL, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_START, 4, side, fileid, time_to_play, completion_ind);
        else    /*If both sides*/
        {
                /*Play to TDM*/
                result = VAPI_SetMessage(message , CMD_CLASS_CONF_CHANNEL, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_START, 4, 0, fileid, time_to_play, completion_ind);
                /*Play to IP*/
                result |= VAPI_SetMessage(message , CMD_CLASS_CONF_CHANNEL, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_START, 4, 1, fileid, time_to_play, completion_ind);
        }
        if(result != SUCCESS)
                goto out;

        result = VAPI_SendConnectionMessage(conn_id, (SMsg *)message, NULL, device_response, &response_len);

out:
        VAPI_FreeMessage (message);
        return result;
}


/*=================================================================================*/
/*=================================================================================*/
VSTATUS stop_playback_buffer(unsigned int conn_id,
                                unsigned int side,
                                unsigned int time_to_stop)
{
        VSTATUS result;

        void *message;
        U32 response_len = DEFAULT_FIFO_MAX_SIZE;
        U8 device_response [DEFAULT_FIFO_MAX_SIZE];

        /* allocate a message to query the current VCEOPT */
        message = VAPI_AllocateMessage(DEFAULT_FIFO_MAX_SIZE);
        if (message == NULL)
                return -1;

        /*If not both sides, stop the required side*/
        if (side != 2)
                result = VAPI_SetMessage(message , CMD_CLASS_CONF_CHANNEL, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_STOP, 2, side, time_to_stop);
        else
        {
                /*Stop TDM */
                result = VAPI_SetMessage(message , CMD_CLASS_CONF_CHANNEL, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_STOP, 0, side, time_to_stop);

                /*Stop IP */
                result |= VAPI_SetMessage(message , CMD_CLASS_CONF_CHANNEL, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_STOP, 1, side, time_to_stop);
        }

        if(result != SUCCESS)
                goto out;

        result = VAPI_SendConnectionMessage(conn_id, (SMsg *)message, NULL, device_response, &response_len);

out:
        VAPI_FreeMessage (message);
        return result;
}

/************************************************************************************************
THIS FUNCTION ***MUST BE CALLED*** JUST AFTER VAPI_OpenDevice()
This is required if extended MSP memory is needed.
Basically if more than 256K of memory is required for local memory playback 
*************************************************************************************************/
/*=================================================================================*/
/*=================================================================================*/
VSTATUS extend_memory_setup(unsigned int dev_id, unsigned int ext_mem_size, unsigned int cachable_heap_size)
{
        VSTATUS result;

        void *message;
        U32 response_len = DEFAULT_FIFO_MAX_SIZE;
        U8 device_response [DEFAULT_FIFO_MAX_SIZE];

        /* allocate a message to query the current VCEOPT */
        message = VAPI_AllocateMessage(DEFAULT_FIFO_MAX_SIZE);
        if (message == NULL)
                return -1;

        result = VAPI_SetMessage(message , CMD_CLASS_CONF_DEVICE, CMD_TYPE_CONF_CHANGE,
                                        FC_EXT_MEM_SETUP,
                                        2, /* 2 parameters */
                                        ext_mem_size, cachable_heap_size);

        if(result != SUCCESS)
                goto out;

        result = VAPI_SendDeviceMessage(dev_id, (SMsg *)message, NULL, device_response, &response_len);

out:
        VAPI_FreeMessage (message);
        return result;
}

/*=================================================================================*/
/*=================================================================================*/
VSTATUS set_playback_buffer(unsigned int dev_id,
                                Boolean action,
                                unsigned int file_number,
                                unsigned int buffer_size)
{
        VSTATUS result;

        void *message;
        U32 response_len = DEFAULT_FIFO_MAX_SIZE;
        U8 device_response [DEFAULT_FIFO_MAX_SIZE];

        /* allocate a message to query the current VCEOPT */
        message = VAPI_AllocateMessage(DEFAULT_FIFO_MAX_SIZE);
        if (message == NULL)
                return -1;

        result = VAPI_SetMessage(message , CMD_CLASS_CONF_DEVICE, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_SET_BUFFER,
                                        4, /* 4 parameters */
                                        action,
                                        file_number,
                                        buffer_size,
                                        buffer_size >> 16);

        if(result != SUCCESS)
                goto out;

        result = VAPI_SendDeviceMessage(dev_id, (SMsg *)message, NULL, device_response, &response_len);

out:
        VAPI_FreeMessage (message);
        return result;
}


/*=================================================================================*/
/*=================================================================================*/
VSTATUS set_playback_file(unsigned int dev_id,
                        unsigned int file_id,
                        char pt,
                        unsigned int file_size,
                        unsigned char *file)
{

        VSTATUS result;
        unsigned int byte_to_send;
        unsigned int offset = 0;
        unsigned len = 0;

        void *message;
        U16 ext_sync_eof[MAX_SYNCEOF_SIZE];

        U32 response_len = DEFAULT_FIFO_MAX_SIZE;
        U8 device_response [DEFAULT_FIFO_MAX_SIZE];

        /*Build the PLAYBACK_SET_FILE and sent it to the MSP*/
        message = VAPI_AllocateMessage(DEFAULT_FIFO_MAX_SIZE);
        if (message == NULL)
                return -1;

        result = VAPI_SetMessage(message , CMD_CLASS_CONF_DEVICE, CMD_TYPE_CONF_CHANGE,
                                        FC_PLAYBACK_SET_FILE,
                                        4, /* 4 parameters */
                                        file_id,
                                        pt,
                                        file_size,
                                        file_size >> 16);

        if(result != SUCCESS)
                goto out;

        result = VAPI_SendDeviceMessage(dev_id, (SMsg *)message, NULL, device_response, &response_len);

        /*Now build as many Extended SYNCEOF messages required to load the full file to the MSP buffer*/
        VAPI_InitMessage(message);
        response_len = DEFAULT_FIFO_MAX_SIZE;

        byte_to_send = file_size;

        while(byte_to_send > 0)
        {
                UT_MemSet(ext_sync_eof, 0 , MAX_SYNCEOF_SIZE);
                VAPI_InitMessage(message);
                response_len = DEFAULT_FIFO_MAX_SIZE;

                if(byte_to_send < MAX_SYNCEOF_DATA)
                        len = byte_to_send ;
                else
                        len = MAX_SYNCEOF_DATA;

                ext_sync_eof[0] = PACKET_TYPE_LOAD_PLAYBACK;
                ext_sync_eof[2] = file_id;
                ext_sync_eof[4] = offset;
                ext_sync_eof[5] = offset >> 16;
                UT_MemCopy(&ext_sync_eof[6], &file[offset], len);

                result = VAPI_SetMessageFromBuffer(message , CMD_CLASS_CONF_DEVICE, CMD_TYPE_CONF_CHANGE,
                                                FC_SYNCEOF,
                                                (len + 12)/2, ext_sync_eof);

                result = VAPI_SendDeviceMessage(dev_id, (SMsg *)message, NULL, device_response, &response_len);

                byte_to_send -= len;
                offset += len;
        }

out:
        VAPI_FreeMessage (message);

        return result;
}


unsigned char myfile_pattern_data[100];

VSTATUS init_playback(int device_id)
{
        VSTATUS status;
        /*With 16M of SDRAM for the MSP only 256k can be reserved for playback buffer*/
        status = set_playback_buffer(device_id, 0, 1, 1024*256);

        status = set_playback_file(device_id, 1, VOIP_VOPENA_RTP_PT_PCMA,
                                        sizeof(myfile_pattern_data),
                                        (unsigned char *)myfile_pattern_data);
        return status;
}

VSTATUS play_myfile_tone_pattern(unsigned int conn_id)
{
        VSTATUS status;
        /*Play file ID 1 to TDM forever*/
        status = start_playback_buffer(conn_id, 1, 0, 0xff, 0);

        return status;
}