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The ADV7482 is an integrated video decoder and HDMI® receiver, targeted at connectivity enabled head units requiring a wired, uncompressed digital audio...
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ADV7482 on Analog.com

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[ADV7482] Time (Latency) from input to output of Video.



		

			

									
					    Tamu
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Apr 11, 2022 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    

    I have some questions about time (Latency) from input to output of Video for ADV7482.
    

    Background:
     My customer uses ADV7482 for their project.
     He will use ADV7482 for CVBS input, Component (YPbPr) input, S-Video (Y/C) input and HDMI input.
     He wants to know the time (Latency) from input to output of Video for developing their software.
    

    About CVBS input, I think the latency depends on the script.
    I see following thread.
    ez.analog.com/.../fast-switch-mode--adv728x
    

    In fast-switch-script, it says "Fast switch mode allows the ADV7182/728x video decoders to lock to single-ended CVBS or differential CVBS video in under 250 ms."
    In normal-script, I think it may takes more than 1 second (typical 1 second) from CVBS input to output.
    So I will answer the times ("Max 250ms in fast-switch-script" and "Typ 1 second in normal-script") to the customer.
    If it has any problem, please let me know.
    

    Questions:
    Q1 : 
     There are no fast-switch-script for Component (YPbPr) input, S-Video (Y/C) input.
     In this case, I think it may takes "typical 1 second" from Component or S-Video input to output.
     Is this right?
    

    Q2 :
     There is a thread in case of HDMI input as follows:
     ez.analog.com/.../425790
     You said " I beleive, Customers can use 100ms and then we have plenty of time to achieve the lock by assuming a good video input. In our software also we are using the100ms polling."
     So I think it may takes "typical 100ms" from HDMI input to output.
     Is this right?
    

    Is it OK that I answer "typical 1 second from Component or S-Video input to output" and "typical 100ms from HDMI input to output" to the customer?
    If you have any other time (Latency) from input to output, could you tell me it?
    If possible, we want to know the maximum time. But if you don't have the maximum time, typical time is OK.
    

    Thank you!
    Best regards.
    Tamu
    
									
			        
		
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			


				
	









	
      
	

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													+1
							
			
				
									
							        
			
			
			
      •  Analog Employees  
      •  Super User  
      
            
			                            
                        
                on Apr 12, 2022 5:52 AM
            
            
					
      
	
      

		
		
      
					
      Hi Tamu-San,
      

             Please find the below comments,
      

       Q1 : 
      

        YES,  When referring ADV748x script, It seems fast switch bit is only enabled for CVBS input but its not applied for component and S-Video.
      

              In standard mode the counter will count for approximately 1 second before setting the IN_LOCK bit high and in fast switch mode the counter will count for approximately 250 ms before setting the IN_LOCK bit high.
      

         Please note customer need to know is that the the CVBS signal needs to be presented with all the parameters of the CVBS signal with the requirements designated in the ADV748x datasheet. If these are presented correctly then the ADV748x  will lock to the video in under 1 second. If these signals are not presented correctly some/all of the time, then it will take the ADV748x longer to lock to the video source. But we cannot tell how much longer this will take or a maximum possible lock time.
      

      Q2 :
      

        I beleive Yes.
      

         But As stated earlier, In software customer need to confirm by adding the GetCurrentMsCount(); between the appropriate locking registers to get the exact locking time.
      

      

      Thanks,
      

      Poornima
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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