[dvblast-devel] Problems with some pro CAMs

[Marian Ďurkovič]

Hi,

  what you describe is basically a broken CAM firmware. Dvblast sends CAPMTs to
the CAM as fast as it accepts data - i.e. once we get ACK from the CAM, we send
another CAPMT. A decent CAM shouldn't send us ACK if it hasn't processed the
data and in no case should it overwrite/overrun its internal buffer and loose
previous CAPMTs.

  The -W switch in 1.2 was there to artificially slow down the rate at which we
send CAPMTs, the wait time was 100 msec. This was enough for buggy PowerCAMs at
that time, but later PowerCAM revisions don't have this problem anymore (well,
they have other major problem of not being able to decrypt TS with bitrate above
48 Mbit/s, sigh)

  I'm quite disappointed to hear that other CAMs suffer from this as well.

  I suggest you to try with 1.2 but increase the CAPMT_WAIT to 500 msec, 1 sec
or whatever is needed for your CAMs. Please report if this helps and how big
waiting is necessary.

  And yes, CAMPT_WAIT is not used since async CAM I/O, since we hoped these
buffer overrun problems were already fixed by CAM manufacturers...

   With kind regards,

       M.

   

On Fri, 07 Jan 2011 22:19:33 +0200, NetOne - Doychin Dokov wrote
> I'm using TT S2-3650 CI on Debian Squeeze, x64, 2.6.35.10, s2-
> liplianin, dvblast latest SVN r178.
> 
> There are problems initializing correctly some CAM modules to decrypt 
> more than 1 services:
> 1) AlphaCrypt Pro, v. 3.20
> When the module is initialized, it starts functioning correctly, but 
> random parts of the stream are not decrypted. This results in random 
> hickups, and may occur from once in a couple of hours to at least one 
> in 5 minutes, depending on encryption and number of channels. 2) 
> Viaccess 1.0 V484 When it is initialized, only the last added CAPMT is 
> functioning correctly, so only the service with the highest SID is decrypted.
> 
> Both problems have very interesting solution:
> 1. Comment out all lines in the dvblast config file
> 2. Do a dvblast reload
> 3. Uncomment the first service
> 4. Do a dvblast reload
> 5. Uncomment the next service
> 6. Do a reload
> ...
> and so on until all services get uncommented. The result is:
> 1. AlphaCrypt Pro decrypts 100% of the streams without glitches.
> 2. Viaccess decodes all channels correctly.
> 
> The problem is, the solution works until dvblast resets the CI module 
> for some reason ( e.g. transport error), then if you do the 
> commenting/uncommenting/reloading stuff again, it starts working correctly.
> 
> I've also tried the 1.2 release with the -W option - same problem, 
> same solution.
> 
> Both modules work fine in a professional headend. When used with 
> PowerCAM Pro, dvblast does not expose this problem.
> 
> Also, I notice in the latest SVN, there is a CAMPT_WAIT defined, but 
> never used. Is this correct? Is it because of the new async io?
> 
> Any ideas what i could further try / test to fix / help with this problem?
> 
> Kind regards,
> Doychin
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