[opendtv] Re: More Questions

  • From: Ron Economos <k6mpg@xxxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Sat, 19 Nov 2005 03:11:23 -0800

Sorry, I meant to say "for every resolution/frame rate"

1920x1080@30 = 2200 total samples per line, 280 blanking samples
1920x1080@25 = 2640 total samples per line, 720 blanking samples
1920x1080@24 = 2750 total samples per line, 830 blanking samples

1280x720@60 = 1650 total sample per line, 370 blanking samples
1280x720@50 = 1980 total sample per line, 700 blanking samples
1280x720@30 = 3300 total sample per line, 2020 blanking samples
1280x720@25 = 3960 total sample per line, 2680 blanking samples
1280x720@24 = 4125 total sample per line, 2845 blanking samples

Note that 720p@24 is an odd number of total samples per line, which can
be a bit of a problem in 4:2:2.

Also, an interface that runs at two different rates, 1.485 Gbps and
1.485/1.001 Gbps, seems awfully video-centric to me.

Ron

Ron Economos wrote:

>There's no "padding" in SMPTE 292M. For every resolution,
>the amount of horizontal blanking changes.
>
>Ron
>
>Craig Birkmaier wrote:
>
>  
>
>>Mark has already gone through the math for the two most demanding HD 
>>formats used in the ATSC system, but 292M can do many other tricks. 
>>In essence, 292M is one of the first SMPTE standards to decouple the 
>>transport from the payload. Earlier standards such as SMPTE-259 are 
>>synchronous digital transports including the blanking intervals and 
>>specific timing references that must occur at the right moment in 
>>time.
>>
>>With 292M we have moved into the real digital era, where the 
>>transport is just a big bit bucket that can carry anything that will 
>>fit. Thus you can also transport 720@30P, 720 @24P, 1080@30P, 
>>108@24P, by padding out the packets that are not used; or you could 
>>move them at 2X real time, or move virtually any digital file across 
>>the transport at ~1.5 Gbps. We also have many examples of using dual 
>>292M links to transport more information - for example some of the 
>>digital cinema cameras use dual links to transport 1920 x 1080 full 
>>bandwidth RGB  signals to disk storage.
>>
>>Regards
>>Craig
>>    
>>

 
 
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