[linux-dvb] Re: [PATCH] Skystar2 pid filters reorganization

[Ralph Metzler <rjkm@metzlerbros.de>]

Roberto Ragusa writes:
 > Every accepted packet is tested twice.
 > Discarded packets are tested once (and very early).
 > So we gain here and loose there.
 > 
 > In relation to "one of the first checks", do you think that the swfilter
 > code is fast enough to let us just open_whole_bandwith when we're out of
 > hw filters?
 > 
 > Consider that the unwanted/wanted ratio can be 5 or 10 in typical
 > usage and much higher in particular cases (we have to open
 > everything when scan is asking 10 pids).
 > 
 > What do you think?

There is no reason it should not work. After all, it works fine with 
the other budget cards without any hardware filters.

The current linuxtv version filter even has a bigger lookup time
(O(1)) to discard/accept filters compared to the older version with
constant lookup time. But the latter only supported one filter per PID.
One could write a new one with constant lookup and multiple filters if you
really need it. But compared to e.g. the performance needed for MPEG2 
decoding the difference is probably negligible.


Ralph




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