IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
> Reed-Solomon coding in DVB TS, How to generate 204b packet from 188b packet
eclipse
post Sep 4 2012, 06:01 PM
Post #1


Be nice to me, I am new.


Group: New Members
Posts: 1
Joined: 4-September 12
Member No.: 15,146
Card: None


Hi,

I want to write my own Reed-Solomon generator for DVB transport streams. I did some research about it I don't understand few things.

First of all, I found the the generator polynomial in DVB is g(x) = 1 + x^2 + x^3 + x^4 + x^8.
Also, we are using RS coding (204, 188), that is shorter version of (255, 239).
From Reed-Solomon theory I now that code word c(x) = m(x) * g(x).

And now what?
How to generate those 16 extra bytes?
Let's assume that I have 188 bytes buffer where is packet, and 204 bytes buffer for the result.

Thanks in advance,
eclipse
Go to the top of the page
 
+Quote Post
bear
post Sep 4 2012, 09:02 PM
Post #2


Forum Regular


Group: Members
Posts: 3,100
Joined: 24-April 04
From: Queensland
Member No.: 808
Card: VisionPlus DVB-t


QUOTE
How to generate those 16 extra bytes?
It is a short-ened version of the RS(255, 239, t = 8) obtained at encoding by adding 51 null bytes before the188 byte packets inorder to form 239 byte blocks applied at the input of an RS(255, 239, t = 8) encoder. This coding adds 16 parity bytes to the end of the original blocks, thus forming new protected 255 byte blocks. After encoding, the first 51 null bytes added before coding are discarded, which gives the new protected transport packets of 204 bytes.

QUOTE
Let's assume that I have 188 bytes buffer where is packet, and 204 bytes buffer for the result
The RS(204, 188, T = 8) coding adds 16 parity bytes after the information bytes of the transport packets, which therefore become 204 bytes long; it can correct up to 8 erroneous bytes per packet.
Go to the top of the page
 
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 16th September 2019 - 06:29 PM