[linux-dvb] Question About DVB API & Air2PC ATSC

Kevin D Fowlks fowlks at msu.edu
Tue Mar 8 15:25:10 CET 2005

Hello, All 

I've written a ATSC scanner application for the Air2PC card that
extracts the VCT sections from a channel that it finds a "Lock" on.
Now this might be a more of a general DVB API question. 

1) The card is supposed to support 32 Hardware PID filters.
  Now for instance my current programs just filters for a TVCT section
  How do I filter for multiply sections? 

I've attempted to fill in other pid sections, But doing this stops the card 
from reciveing ANY sections. It works fine as long as i only use one PID 
Mask pair, hence the coed that commented out. 

unsigned char filter[DMX_FILTER_SIZE];
unsigned char mask[DMX_FILTER_SIZE]; 

memset( filter, '\0', sizeof(filter));
memset( mask, '\0', sizeof(mask)); 

filter[0] = TVCG_TABLE_ID; // Look for the TVCG Table in Stream for OTA   
 //filter[1] = CVCG_TABLE_ID; // Look for the CVCG Table in Stream for Cable 

  mask[0]   = 0xFF; // Mask
 //mask[1]   = 0xFF; // Mask 


2) How do I properly determine "Lock"? I understand that since the signal 
could have errors or bad data or Fade in / out ...etc.  I understand that 
the values returned from the card are not normalized because the values 
might mean something differnt depending on the card and hardware.  Whats the 
correct way to handle this? 

3) Data Timeout what is a good value in the ATSC realm? 


 - Kevin 




Kevin D. Fowlks
fowlks at ais.msu.edu
Information Technologist I                    (517) 353-4420 x258
Administrative Information Services                Fax: (517) 355-5176
Michigan State University 

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