Some more information:
When I use tzap to tune adapter1 to "YLE TV1" multiplex (the situation
that gives a bad image), I get a high bit error rate:
tzap -r -a 1 "YLE TV1"
using '/dev/dvb/adapter1/frontend0' and '/dev/dvb/adapter1/demux0'
tuning to 562000000 Hz
video pid 0x0200, audio pid 0x028a
status 06 | signal ffff | snr 0000 | ber 001fffff | unc 00000000 |
status 1e | signal ffff | snr 0000 | ber 000007d0 | unc 00000012 |
FE_HAS_LOCK
status 1e | signal ffff | snr 0000 | ber 000002c0 | unc 00000000 |
FE_HAS_LOCK
status 1e | signal ffff | snr 0000 | ber 00000130 | unc 00000000 |
FE_HAS_LOCK
However, with the another device, this stream has practically no error
at all:
tzap -r -a 0 "YLE TV1"
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
tuning to 562000000 Hz
video pid 0x0200, audio pid 0x028a
status 06 | signal ffff | snr 0000 | ber 001fffff | unc 00000000 |
status 1e | signal ffff | snr 0000 | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status 1e | signal ffff | snr 0000 | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status 1e | signal ffff | snr 0000 | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
And when trying to tune adapter0 to the multiplex it won't tune into
("partial lock" in MythTV), there's a high amount of "uncorrected block
error":
tzap -r -a 0 "MTV3"
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
tuning to 658000000 Hz
video pid 0x0131, audio pid 0x0231
status 02 | signal ffff | snr 0000 | ber 001fffff | unc 00000000 |
status 1a | signal ffff | snr 0000 | ber 00000000 | unc 00000120 |
FE_HAS_LOCK
status 1a | signal ffff | snr 0000 | ber 00000000 | unc 000001a7 |
FE_HAS_LOCK
status 1a | signal ffff | snr 0000 | ber 00000000 | unc 00000219 |
FE_HAS_LOCK
status 1a | signal ffff | snr 0000 | ber 00000000 | unc 0000028b |
FE_HAS_LOCK
status 1a | signal ffff | snr 0000 | ber 00000000 | unc 00000303 |
FE_HAS_LOCK
Watching the same multiplex with adapter1 has no uncorrected error, but
quite a lot of bit error, this doesn't influence the video quality though:
tzap -r -a 1 "MTV3"
using '/dev/dvb/adapter1/frontend0' and '/dev/dvb/adapter1/demux0'
tuning to 658000000 Hz
video pid 0x0131, audio pid 0x0231
status 06 | signal ffff | snr 0000 | ber 001fffff | unc 00000000 |
status 1e | signal ffff | snr 0000 | ber 00000490 | unc 00000000 |
FE_HAS_LOCK
status 1e | signal ffff | snr 0000 | ber 00000300 | unc 00000000 |
FE_HAS_LOCK
status 1e | signal ffff | snr 0000 | ber 00000350 | unc 00000000 |
FE_HAS_LOCK
However, when I first tune adapter1 to "MTV3" (its "good" channel) and
then adapter0 to the same multiplex (that doesn't show any image), the
bit error rate goes to (near) zero also in adapter1.
One guess would be that the card's "diversity" feature state is
internally somehow on, which prevents the tuners from working
independently (which would also explain the better signal when both are
tuned to same multiplex). Or then again it could be another bug
altogether, but anyway it seems that the tuners aren't working fully
independently.
I browsed through the driver code and found some code about the
diversity in dib7000p.c and dib7000m.c, but my understanding of the
hardware and DVB in general is quite lacking. It seems however that
there's options to enable/disable the diversity through the driver
(contrary to the documentation in the card's wiki entry), but I can't
figure out how to get the configuration to the module (in insmod, ioctl,
sys/proc fs ??).
- Jami
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