On 19.05.2012 21:20, Hans de Goede wrote:
Currently the V4L2 API does not allow for radio devices with more then 1
tuner,
which is a bit of a historical oversight, since many radio devices have 2
tuners/demodulators 1 for FM and one for AM. Trying to model this as 1
tuner
really does not work well, as they have 2 completely separate frequency
bands
they handle, as well as different properties (the FM part usually is stereo
capable, the AM part is not).
It is important to realize here that usually the AM/FM tuners are part
of 1 chip, and often have only 1 frequency register which is used in
both AM/FM modes. IOW it more or less is one tuner, but with 2 modes,
and from a V4L2 API pov these modes are best modeled as 2 tuners.
This is at least true for the radio-cadet card and the tea575x,
which are the only 2 AM capable radio devices we currently know about.
For DVB API we changed just opposite direction - from multi-frontend to
single-frontend. I think one device per one standard is good choice.
From DVB FE change there is now some problems as a frequency limits and
other parameters are shared between all the standards... For example
cxd2820r demod, which is DVB-T/T2/C, says it supports even DVB-C2 as 2nd
generation flag is derived from the DVB-T2.
regards
Antti
--
http://palosaari.fi/
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