Transmission with Record Timing

Transmission with record timing means the records are scheduled on the time tag set for each record.

Each time tag specifies a clock value defining when the record must be transmitted.

The option MXF_TXAPERIODIC_FLAG_USE_RECORD_ABSOLUTE_TIME must be used for this type of transmission.

In the example below, the records are sent based on the absolute clock timing specified in the time tag field for each records.

ar429_aperiodic.c

#define BUFFER_SIZE     4096 // 4KB
#define MAX_TX_RECORDS_TO_TRANSMIT 8

HMXF_SERVER server;
HMXF_DEVICE device;
HMXF_CHANNEL txChannel;
HMXF_BUFFER  txBuffer=0;
MXF_A429_DATAREC *rec429=NULL;
MXF_A429_DATAREC *rec;
uint32 label, sdi, data, ssm, parity;
uint64 currentTime=0;
uint32 record;
uint64 delay100ms = 100000;
uint32 rc;

   ...

   // Sets timebase to 64-bit microseconds
   if (!rc)
      rc = mxfSystemTimeBaseSet(server, MXF_TIMEBASE_DEVICE_USEC);

   // Allocates Aperiodic TX static buffer for HIGH priority queue
   if (!rc)
      rc = mxfTxAperiodicBufferAlloc(txChannel, MXF_TXAPERIODIC_PRIORITY_HIGH, BUFFER_SIZE, &txBuffer, NULL);

   // Allocates host buffer
   if (!rc)
   {
      rec429 = (MXF_A429_DATAREC*)malloc(BUFFER_SIZE);
      if (!rec429)
         rc = MAXT_ERROR_MEM;
   }

   // Gets the current time
   if(!rc)
      rc = mxfDeviceTimerGet(device, &currentTime);

   currentTime += delay100ms;

   // Sets the records: ARINC 429 LABEL=007, SDI=1
   rec = rec429;
   for (record=0; record < MAX_TX_RECORDS_TO_TRANSMIT && !rc; record++)
   {
      rec->timeTag = currentTime+((record+1)*10000LL);
      rec->control = 0;
      rec->repeatCount = 1;
      rec->reserved = 0;

      label = 7;
      sdi = 1;
      data = record*32;
      ssm = 0;
      parity = VMXF_A429_PARITY_ODD;
      rc = mxfA429ArwCompose(label, sdi, data, ssm, parity, &rec->data);
      if(!rc)
         rc = mxfA429NextDataRecordPtrGet(rec, &rec);
   }

    // Transmits the array of records
    if (!rc)
      rc = mxfA429TxAperiodicWrite(txBuffer, MXF_TXAPERIODIC_FLAG_USE_RECORD_ABSOLUTE_TIME, 0, MAX_TX_RECORDS_TO_TRANSMIT, rec429);

    if (rec429)
      free(rec429);

   ...

}