Re: TechnoTrend Budget CI stutters and often fails at tuning encrypted channel.

[Oliver Schinagl <oliver+list@schinagl.nl>]

On 17-07-12 10:30, Oliver Schinagl wrote:
> Hi list,
>
> I have been using a tt1500, a saa7146 PCI DVB-T tuner for well over a 
> year now. Running gentoo 64bit tracking the ~amd64 branch (that only 
> get bi-monthly upgraded) I've been always more or less up to date.
>
> This card however has never properly worked. I've been running vdr 
> 1.6.* since that is what's stably in gentoo. Whilst writing this down 
> I realized I still have to test me-tv to double check my findings.
>
> Some background info. Here in NL we have 4 FTA channels and about 20 
> conax encrypted channels that the CAM in the CI module decrypts. I 
> have two smartcards, of which one is only in active use at the moment.
>
> When changing channels between the FTA channels, the first 'bug' 
> occurs. Somtimes (not predictably or anything, about 50% of the 
> channel changes) sound stutters the first few seconds, upto 30 seconds 
> sometimes. It sounds almost if the sound is being fed through some 
> sort of PWM, that slowly catches up. So first you hear 1 second of 
> audio, 3 seconds of nothing, then 1 second of audio again, then 2 
> seconds of nothing etc. This audio delay is random. E.g. sometimes it 
> stutters for about 30 seconds while it has a hard time to catch up, 
> other times the audio needs only 2 or 3 seconds to catch up. Very 
> occasionally it instantly works right. The stuttering appears to be 
> worse on encrypted channels.
>
> Encrypted channels has the additional annoyance, that quote often, an 
> entire channel is not available. That is, every channel in its bouqet. 
> Simply waiting on that channel for about a minute or two, mysteriously 
> brings the unavailable channel up. Allthough it 'feels' like changing 
> channel helps this fix faster, it's just a placebo effect if you ask 
> me ;)
>
> I cannot safely say that the same skipping happens to the video, I 
> have not noticed it really. I have checked signal strength etc and 
> though the strength is only at 55%, the SNR is at 99% quite stable and 
> the BER (unrecoverable errors? are at 0). If for some reason there is 
> interferance, bad whether, blocked antenna, then the BER goes up 
> followed by distorted imagery and with really bad signal bad audio as 
> well (humans are more sensitive to bad audio iirc).
>
> I'm not sure what to profile, where to enable debugging, what logs to 
> check or what to do to help 'fix' this.
>
> lspci output:
> 00:0a.0 Multimedia controller: Philips Semiconductors SAA7146 (rev 01)
>              Subsystem: Technotrend Systemtechnik GmbH DVB T-1500
>              Flags: bus master, medium devsel, latency 32, IRQ 18
>              Memory at f0162000 (32-bit, non-prefetchable) [size=512]
>              Kernel drive in use: budget_ci dvb
>
> /proc/interrupts
> 18:                499    107651  IO-APIC-fasteoi   saa7146  (0)
>
> Tuner: tda10046h dvb-t, firmware revision 20
>
>
> Thank you for your time,
> oliver
P.S. I forgot to mention, that once tuned to a channel, I can receive 
(and decode) it fine for many hours. I think the longest I had one 
channel up was about 8 hours or so without issue. A dvb-t radio channel 
(thus not dab) i had up for even longer, so once it goes, it goes on 
happily forever!