[linux-dvb] Tzap utilities questions - status of TDA10046

Hartmut Hackmann hartmut.hackmann at t-online.de
Wed Sep 20 23:31:20 CEST 2006


Hi,

Chun Chung Lo wrote:
> Hi,
> 
> Thanks for your quick reply.
> 
> But do you know any other factors that will cause the corruption of
> captured TS ?
> 
> I have checked no interrupt lost during I capturing TS.
> 
> Thanks for your help.
> 
> Best regards,
> Lo Chun Chung
> 
> -----Original Message-----
> From: linux-dvb-bounces at linuxtv.org
> [mailto:linux-dvb-bounces at linuxtv.org] On Behalf Of Georg Acher
> Sent: Wednesday, 20 September, 2006 10:03 AM
> To: linux-dvb at linuxtv.org
> Subject: Re: [linux-dvb] Tzap utilities questions - status of TDA10046
> 
> 
> On Wed, Sep 20, 2006 at 09:51:42AM +0800, Chun Chung Lo wrote:
> 
>>Hi,
>>
>>So you mean that the "ber" occurence will not related to the captured
>>TS quality ?
> 
> 
> Not with this low ber value. If it increases (>0x5000-0xa000 in my
> experience), you will get errors in the TS.
> 
> 
>>I would like to clarify my question, which is as the status screen
>>dump is shown below, the captured TS quality is so bad, some flahsing
>>squares will appear on some frames randomly at some instance (just
>>seems the captured TS packets are corruppted and missing).
> 
> 
> If the reception is that bad, you should have at least unc != 0 a few
> times.
> 
> --
>          Georg Acher, acher at in.tum.de        
>          http://www.lrr.in.tum.de/~acher
>          "Oh no, not again !" The bowl of petunias         
> 
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> 
As Georg already mentioned, the value for ber is before error correction.
Your tzap log indicates an almost perfect signal.
I am not sure what you mean with bad TS quality, is the stream corrupted?
4MBit is not much for critical patterns.
But if you see a corrupted Stream, either your generator does something
wrong (packet formatting), or - more likely - you have a problem with
the TS - DMA.
If your work is based on Gerd Knorrs driver, you need to be aware that it
has a bug in the TS DMA. I fixed this in the v4l-dvb repository about a
year ago. This can easily be the cause for your problem. You also need
to know that the SAA713x can not handle TS streaming and analog video
in a planar format parallel. If you try to do so, both streams will be
corrupted since they go over the same DMA engine.

Hartmut



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