On 01/17/2013 11:29 PM, Manu Abraham wrote:
On Fri, Jan 18, 2013 at 12:41 AM, Antti Palosaari <crope@xxxxxx> wrote:
On 01/17/2013 08:50 PM, Mauro Carvalho Chehab wrote:
Em Fri, 18 Jan 2013 00:07:17 +0530
Manu Abraham <abraham.manu@xxxxxxxxx> escreveu:
On Thu, Jan 17, 2013 at 11:57 PM, Antti Palosaari <crope@xxxxxx> wrote:
Resetting counters when user tunes channel sounds the only correct
option.
This might not be correct, especially when we have true Multiple Input
Streams.
The tune might be single, but the filter setup would be different. In
which case it
wouldn't correct to do a reset of the counters ona tune. Resetting the
counters
should be the responsibility of the driver.
I moved the counters reset to the driver's logic on v11. I'm posting the
patches in a few.
As I said in an earlier
post, anything
other than the driver handling any statistical event monitoring, such an
API is
broken for sure, without even reading single line of code for that API
for which
it is written for.
Yes, driver should have full control on it.
OK, maybe we will see in near future if that works well or not. I think
that
for calculating of PER it is required to start continuous polling to
keep up
total block counters. Maybe updating UCB counter continously needs that
too,
so it should work.
With multi-standard demodulators, some of them PER compute is a
by-product
of some internal demodulator algorithmic operation. In some cases, it
might
require a loop in the driver. As I said, again; It is very hard/wrong
to do basic
generalizations.
Agreed.
I think we will have soon kinda consensus everyone could approve! Anyhow, I
didn't liked that kind of PATCH RFC process. That change was too big for
PATCH style RFC and it was hard to keep track what going on looking those
patches. Maybe requirement specification RFCs first and when requirements
are clear => PATCH RFC for implementation.
What I know understand, requirements are:
signal strength:
==============
Offer both discussed methods.
Simple [0...n] scale and dB...
Driver must support simple scale over dB.
What happens, if the hardware doesn't support any dB scale ?
CNR (SNR)
==============
Offer both discussed methods.
Simple [0...n] scale and dB...
Driver must support simple scale over dB.
Same question here as well.
BER
==============
Offer global BER and per layer BER.
Measure is returned as two numbers, one for error bit count and one for
total bit count.
uncorrected packets/blocks
==============
Offer global UCB and per layer UCB.
Measure is returned as two numbers, one for uncorrected packet count and one
for total packet count.
counter reset
==============
counters are reset when channel is tuned
Counter reset behaviour is a bit undefined, for the reason stated earlier.
ie, the driver should do the reset, as it sees fit rather than common code.
well, it would be correct to state at start of frame count after
stream is initialized.
Initialization of stream can happen on legacy systems: only after successful
synchronous viterbi is achieved. Tuning to a channel doesn't make any sense.
In some of the non-legacy systems, stream initialization would happen
on a filter
setup change as well. It is not dependent on a channel switch/tune.
And if we end up returning "simple" values over dB values, then I think
driver could be simple and implement only dB and dvb-core is responsible to
convert dB => simple. That should quite be possible as we know which dB
value is good signal and which is bad signal.
Again, not all devices can output in dB.
Manu
I was a little bit unclear? There is two supported methods for SS and
CNR, dB and relative scale to some defined range. If driver supports dB
then dB is used, and if not then then relative scale is used.
My propose was to ask if we could add some generic calculations for the
DVB-core, so that implementing only one method for the driver is enough.
If app is asking relative value and driver does dB, then DVB-core makes
conversion. For CNR, take CNR dB and modulation, return relative value
for app. For SS conversion is even simpler.
regards
Antti
--
http://palosaari.fi/
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