Reads data at the current position in the current message.

DWORD vceRead ( CTAHD ctahd,
BYTE *buffer,
unsigned bytes,
unsigned *bytesread)

ctahd Handle returned by ctaCreateContext.

buffer Pointer to a buffer to receive data.

bytes Amount of data to read.

bytesread Pointer to the returned number of bytes read.

• SUCCESS
• CTAERR_FUNCTION_ACTIVE
  Playing or recording is active on the context.
• CTAERR_INVALID_CTAHD
• VCEERR_NO_MESSAGE
  There is no current message in the context.

• None.

This function copies the specified number of bytes of data at the current location in the current message in the context specified by ctahd to a specified buffer. It returns the number of bytes read in bytesread, unless bytesread is NULL.

The number of bytes read will always be an integral multiple of the framesize of the current message. If you specify a buffer size that is not a multiple of the framesize, the number of bytes read will be smaller than the requested size.

You cannot read while play or record is active.

If you attempt to read beyond the end of the current message, SUCCESS will be returned and the current position will be set to the end of the current message.

The current position will be advanced by the amount read in millisecond units.

To convert between bytes and milliseconds, use vceGetContextInfo to get the frame size and frame time, then use the following formulas:

 milliseconds = (bytes / framesize) * frametime
 bytes = (milliseconds / frametime) * framesize

vceGetContextInfo, vceWrite

/* Read a message into memory */
void myLoadMessage (CTAHD ctahd, VCEHD vh, unsigned message,
                   BYTE **returned_address, unsigned *returned_msec,
                   unsigned *returned_bytes)
{
    VCE_CONTEXT_INFO contextinfo;
    unsigned         msec;
    unsigned         bytes;
    unsigned         bytesread;
    BYTE            *buffer;

    *returned_address = NULL;
    *returned_msec    = 0;

    vceSetCurrentMessage (vh, message) ;
    vceGetCurrentSize (ctahd, &msec) ;
    if (msec == 0)
        return ;

    /* Convert the size from milliseconds to bytes */
    vceGetContextInfo (ctahd, &contextinfo, sizeof contextinfo);
    bytes = msec / contextinfo.frametime * contextinfo.framesize;
    buffer = malloc(bytes) ;

    vceRead (ctahd, buffer, bytes, &bytesread);
    *returned_address = buffer;
    *returned_msec    = msec;
    *returned_bytes   = bytes;
    return;
}