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Opened 7 years ago

Last modified 5 years ago

#8731 assigned Bug Report - General

DVB-T scan: muxes not tuned during full scan but tuned using NIT info

Reported by: Nick Morrott <knowledgejunkie (at) gmail (dot) com> Owned by: stuarta
Priority: minor Milestone: unknown
Component: MythTV - Channel Scanner Version: Master Head
Severity: medium Keywords: dvb-t missing multiplexes full scan
Cc: Ticket locked: no

Description

Using the same configuration as reported in #8726.

Scan details: full UK scan using Sutton Coldfield transmitter with 6 available muxes. Signal/tuning timeouts raised to 2000/6000ms. ALL services (DVB+MPEG) scanned, with decryption testing disabled.

During the scan, a signal and successful lock is achieved on only 1 of the possible muxes (746000000), even when using doubled timeouts. The remaining 5 muxes are discovered in the NIT of this mux, and subsequent tuning of these muxes is successful.

Checking the log output reveals the following for sample mux 634166670:

i) During the initial full scan using default scan parameters, the following was seen:

                        DVBChan(1:/dev/dvb/adapter102/frontend0): New Params: 634166670 auto 0 auto auto 8 a 1/32 n v fec: auto msys: UNDEFINED rolloff: 0.35
2010-08-05 06:42:04.455 DVBChan(1:/dev/dvb/adapter102/frontend0): Tune(): Frequency tuning successful.
2010-08-05 06:42:04.455 DTVSM(/dev/dvb/adapter102/frontend0)::SetChannel(-1, -1):
2010-08-05 06:42:04.455 SM(/dev/dvb/adapter102/frontend0)::Start: begin
2010-08-05 06:42:04.455 SM(/dev/dvb/adapter102/frontend0)::Start: end
2010-08-05 06:42:04.504 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:04.504 SM(/dev/dvb/adapter102/frontend0)::RemoveFlags: Seen() Match() Wait(Pos,)
2010-08-05 06:42:04.566 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:04.628 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:04.690 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:04.752 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:04.814 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:04.876 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:04.937 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:05.893 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:05.955 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.017 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.079 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.141 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.203 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.264 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.326 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.388 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:42:06.449 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)

No signal is seen within the 2000ms timeout value

ii) Having extracted this sample mux's details from the NIT of the 1 mux locked to (746000000), the later "fill-in" scan was succesful:

                        DVBChan(1:/dev/dvb/adapter102/frontend0): New Params: 634166670 qam_16 a 3/4 3/4 8 2 1/32 n v fec: auto msys: UNDEFINED rolloff: 0.35
2010-08-05 06:45:51.455 DVBChan(1:/dev/dvb/adapter102/frontend0): Tune(): Tuning to 634166670Hz
2010-08-05 06:45:52.356 dvbchannel.cpp:wait_for_backend: Status:
2010-08-05 06:45:52.356 DVBChan(1:/dev/dvb/adapter102/frontend0): Tune(): Frequency tuning successful.
2010-08-05 06:45:52.356 DTVSM(/dev/dvb/adapter102/frontend0)::SetChannel(-1, -1):
2010-08-05 06:45:52.356 SM(/dev/dvb/adapter102/frontend0)::Start: begin
2010-08-05 06:45:52.356 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:45:52.356 SM(/dev/dvb/adapter102/frontend0)::Start: end
2010-08-05 06:45:52.356 SM(/dev/dvb/adapter102/frontend0)::RemoveFlags: Seen() Match() Wait(Pos,)
2010-08-05 06:45:52.420 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:45:52.481 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen() Match() Wait(Sig,)
2010-08-05 06:45:52.510 DVBSM(/dev/dvb/adapter102/frontend0): UpdateValues -- Signal Locked
2010-08-05 06:45:52.540 SM(/dev/dvb/adapter102/frontend0)::AddFlags: Seen(PAT,) Match() Wait()
2010-08-05 06:45:52.540 ChannelScanSM(/dev/dvb/adapter102/frontend0): Got a Program Association Table for TransportID 4101

Is it possible to modify the default scan parameters in order to increase the likelihood of finding more/all muxes during the initial scan?

Full log output of the scan is attached.

Attachments (1)

8731-dvbt-uk-fullscan-r25561.log.bz2 (34.8 KB) - added by Nick Morrott <knowledgejunkie (at) gmail (dot) com> 7 years ago.
DVB-T, UK, Full scan

Download all attachments as: .zip

Change History (4)

Changed 7 years ago by Nick Morrott <knowledgejunkie (at) gmail (dot) com>

DVB-T, UK, Full scan

comment:1 Changed 7 years ago by robertm

  • Owner changed from danielk to stuarta
  • Status changed from new to assigned

comment:2 Changed 6 years ago by stuartm

  • Type changed from defect to Bug Report - General

comment:3 Changed 5 years ago by dekarl@…

Comparing both sets of tuning parameters suggests that the auto detection of one of the parameters does not work.

DVBChan(1:/dev/dvb/adapter102/frontend0): New Params: 634166670   auto 0 auto auto 8 a 1/32 n v fec: auto msys: UNDEFINED rolloff: 0.35
DVBChan(1:/dev/dvb/adapter102/frontend0): New Params: 634166670 qam_16 a  3/4  3/4 8 2 1/32 n v fec: auto msys: UNDEFINED rolloff: 0.35

The proper fix involves querying the driver's/device's capabilities and try all combinations of parameters where autodetection is not supported.

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