Hello,
sometimes, I experience non-deterministic problems with tuning on some
transponders with dvb-s. For example, on astra-H-11954, I have about
50% chance to get a good tune. If I get a bad tune, I still receive
TS packets from the chosen transponder, but about 10%..20% of the
packets are lost. The (remaining) packets contain PAT/PMT/PES packets
from the chosen transponder, so it is pretty safe to assume that
actual tuning worked properly.
What I do is pretty much straight forward:
1. open frontend/dmx/dvr devices
2. send diseqc command to switch to desired input
3. use FE_SET_FRONTEND ioctl to tune to desired transponder
4. wait for FE_HAS_LOCK
5. set dmx_pesfilter_params to:
pid: 0x2000 /* yes, I want the whole transponder */
input: DMX_IN_FRONTEND
output: DMX_OUT_TS_TAP
pes_type: DMX_PES_OTHER
flags: DMX_IMMEDIATE_START
With this sequence, I have about 50% chance to receive a proper TS
stream. When the stream is not OK, I can see about 10%..20% loss
of TS packets.
I have checked signal quality, but there is no significant difference
from working to non-working:
Status:1f sig:ac80 snr:d9e0 ber:00000000 unc:fffffffe FE_HAS_LOCK
Status:1f sig:adbe snr:dac4 ber:00000000 unc:fffffffe FE_HAS_LOCK
So I have tried to narrow the problem, and I think I've come pretty
close (but still no cigar):
Once the sequence (which is listed above) is completed, I can easily
(but randomly, IOW: I have to try 1..3 times) switch from proper stream
to broken stream and vice-versa simply by repeating step 3 with _exactly_
the _same_ values.
To be precise: on an already set-up transponder, re-executing this
function:
static void tune_frequency (int ifreq, int sr)
{
struct dvb_frontend_parameters tuneto;
tuneto.frequency = ifreq*1000;
tuneto.inversion = INVERSION_AUTO;
tuneto.u.qpsk.symbol_rate = sr*1000;
tuneto.u.qpsk.fec_inner = FEC_AUTO;
if (ioctl(fefd, FE_SET_FRONTEND, &tuneto) == -1) {
fatal ("FE_SET_FRONTEND failed: %s\n", strerror (errno));
}
}
with _exactly_ the same values for ifreq and sr, is able to toggle from
good TS stream to bad TS stream or vice-versa. As long as I avoid to
call this function, the quality of the stream does _not_ change.
I have tried to use fixed values instead of *_AUTO for FEC and INVERSION,
but that did not help either.
Any ideas?
BTW:
$ lspci -v
[ ... ]
03:07.0 Multimedia controller: Philips Semiconductors SAA7146 (rev 01)
Subsystem: Technotrend Systemtechnik GmbH Technotrend-Budget/Hauppauge WinTV-NOVA-CI DVB card
Flags: bus master, medium devsel, latency 32, IRQ 21
Memory at fdcfe000 (32-bit, non-prefetchable) [size=512]
Kernel driver in use: budget_ci dvb
Kernel modules: snd-aw2, budget-ci
$ uname -a
Linux raven 2.6.27.7-9-default #1 SMP 2008-12-04 18:10:04 +0100 x86_64 x86_64 x86_64 GNU/Linux
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