Re: cx18, s5h1409: chronic bit errors, only under Linux

[David Ward <david.ward@gatech.edu>]

On 06/08/2009 04:36 PM, Devin Heitmueller wrote:
> On Mon, Jun 8, 2009 at 4:20 PM, Steven Toth<stoth@kernellabs.com>  wrote:
>    
>> We're getting into the realm of 'do you need to amplify and/or debug your
>> cable network', and out of the realm of driver development.
>>      
Comcast is coming tomorrow to check out the signal quality.  They said 
that they expect to deliver SNR in the range of 33dB - 45dB to the 
premises.  I will let you know how that affects Linux captures.
> Steven,
>
> One thing that is interesting is that he is getting BER/UNC errors
> even on ATSC, when he has a 30.2 dB signal.  While I agree that the
> cable company could be sending a weak signal, 30 dB should be plenty
> for ATSC.
>
> Also, it's possible that the playback application/codec in question
> poorly handles recovery from MPEG errors such as discontinuity, which
> results in the experience appearing to be worse under Linux.
>    
I am actually comparing the TS files captured under both Linux and 
Windows side-by-side in the same environment, copying the files to other 
computers in my home.  I can demux the video with Project-X which prints 
out the errors in the bitstream as it reads them.  I can also observe 
the overall quality by playing it back with VLC, WinDVD, etc.  When I 
use TMPGEnc Authoring Works 4 to read the file, the errors in the 
bitstream even seem to crash the application -- though obviously TMPGEnc 
is to blame for that.
> I'm going to see if I can find some cycles to do some testing here
> with s5h1409/s5h1411 and see if I can reproduce what David is seeing.
>
>    
Devin, I would really really appreciate this.  I hesitated to e-mail 
this list for several weeks, because I wanted to investigate thoroughly 
first and avoid wasting anyone's time as much as possible.  I hope you 
are able to reproduce this.

David