[linux-dvb] [RFC]

Hari_Mohan Hari_Mohan at Satyam.Com
Wed Feb 16 11:20:53 CET 2005



-----Original Message-----
From: linux-dvb-bounces at linuxtv.org [mailto:linux-dvb-bounces at linuxtv.org]
On Behalf Of Manu Abraham
Sent: Wednesday, February 16, 2005 3:04 PM
To: Hari_Mohan
Cc: linux-dvb
Subject: Re: [linux-dvb] [RFC]

Hari_Mohan wrote:
> -----Original Message-----
> From: linux-dvb-bounces at linuxtv.org [mailto:linux-dvb-bounces at linuxtv.org]
> On Behalf Of Manu Abraham
> Sent: Wednesday, February 16, 2005 2:11 PM
> To: Hari_Mohan
> Cc: linux-dvb
> Subject: Re: [linux-dvb] [RFC]
> 
> Hari_Mohan wrote:
> 
>>I don't know much about this but I have seen this in a dvb demodulator
>>output and ASI convertors. These lines were termed DVALID and these used
> 
> to
> 
>>stay high whenever there is valid data in the transport stream
>>bus-8bit/serial. This line stays low when there are some special
> 
> characters
> 
>>coming in the bus. I think this flag is related to that. Even error line
>>also is similar - ie whenever there were some uncorrectable errors this is
>>supposed to stay low - depends on your configuration
>>
> 
> What i was wondering was that, whether this information could help in 
> the upper space DVB API/driver in any manner, in terms of error 
> correction and or other aspects.
> ------------------------
> According to my knowledge mpeg decoder chips will clock in the data based
on
> the state of these lines. I don't know whether any hardware mechanism is

So is this information more reliable than the 13818-1 Discontinuity flag.. ?

such that this information can be used to identify cases where we have 
problems in the TS.. ?
since under the Linux DVB API, we don't have an exact solution for 
discontinuity, and TS errors to a 100% effectiveness, would these flags 
be useful for solving that problem ?

For a particular DVB card, i can get these signals out from the frontend 
to the card and the driver.. So, considering that aspect if i get these 
flags out, i was wondering whether it would be possible to have a 
solution for the latter errors..

That was the query that i had in my mind..
********************

The error bit which I am speaking about is the signal which is given by
demodulator or a receiver device once it finds that input ts packet is
errored. But the discontinuity indicator which you refered is inside the
transport stream - so these information which are inside stream are inserted
from the stream generator (encoder/mux) and I don't think that tuner will be
reading this data to give the error signal/flag. 
For discontinuity in transport stream you can tweak software or add some
patches but for errored input signal indication I don't think anything can
be done other than making satellite/cable reception proper.

Hari
**************************
> there to store these values and use for upper layer applications. Because
> stv299 may have separate APIs to calculate BER and signal quality.
> 
> Hari
> ---------------------------------
> 
> 
> 
> 
>>Hari
>>
>>-----Original Message-----
>>From: linux-dvb-bounces at linuxtv.org [mailto:linux-dvb-bounces at linuxtv.org]
>>On Behalf Of Manu Abraham
>>Sent: Wednesday, February 16, 2005 12:27 AM
>>To: linux-dvb
>>Subject: [linux-dvb] [RFC]
>>
>>Hi,
>>
>>Is there any advantage in getting the following flags out from the tuner 
>>(STV0299 based).. such that it might be of some help.. ?
>>
>>(1) data valid
>>(2) error
>>
>>
> 
> 

Manu

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