Manu Abraham wrote:
Manu Abraham wrote:
christophpfister@xxxxxxxxxxx wrote:
2. How does the demod filter? Does it exact matching or intelligent
matching?
-> intelligent matching means that if we use SIS we get the whole
stream
-> exact matching means that we have to use MIS and the correct
stream_id,
otherwise we don't receive anything
Both would be possible (because HP and LP are already
distinguished by
different modcods), but again: We don't know.
See my other post.
Each stream is specific to a PLFrame (Physical Layer Frame) Now for the
Small correction.
The LP stream is specific to a PLFrame (Physical Layer Frame) In
accordance to the figure F.1 in Annex F EN 302 307 p 55, The HP stream
is always DVB-S. Now for the
<continue>
demod to identify which PLFrame you are interested in, you have to tell
demod to identify the PLFrame .. <continue> ..
it something. It doesn't have any magic to know what you want.
This field through which you tell the demod which PLFrame your are
interested in, is through the ISI (Input Stream Identifier)
Thanks for raising this thought.
Manu
Now according to the figure F.1 the HP stream is DVB-S modulated and the
LP stream is DVB_S2 modulated. In this case we can drop the SISMIS flag
and just use the ISI for the LP stream.
So eventually all that any DVB-S2 demod should be interested in the
dvbs2_params are
(1) modulation
(2) fec
(3) rolloff
(4) stream identifier
(5) scrambling sequence index (we don't need this for the stb0899, this
can be used by others if supported by others)
Additionally we may provide the descrambled BBHEADER also which may be
useful as information
(2) MATYPE 1 & 2 (2 bytes)
Looking at an application POV, the application will need to
// check whether the stream has a S2 descriptor
if (s2 descriptor) {
// this is backward compatible mode
// in this mode, check whether the multiple input stream flag exists
if (multiple_input_stream_flag) {
// Now HP & LP stream s exists
// Provide feedback to user that HP/LP streams exists
provide_user_feedback(params);
// get info from user whether he is interested in the HP or LP stream
if (user_feedback == HP) {
// tune to normal DVB-S
} else if (user_feedback == LP) {
// tune to DVB-S2
// to tune to DVB-S2 , we need to send the stream_identifier
// from the s2 satellite delivery system descriptor
tune_dvbs2(params);
}
}
}
In this POV, to provide the user feedback, i think the a feedback
control knob would be nice rather than using ISI in conjunction with
delivery system.
A knob to control it, such as STREAM_PRIO_HP/STREAM_PRIO_LP , But this
is at an application POV, not the API.
But to make applications consistent with this control, we may use this
control in the API itself.
Manu
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