Any day you learn something new is a good day


Further adventures in Mythbuntu: the advent of DVB-S cards

, posted: 30-Jan-2009 13:27

I've had a productive week... got given a decent desktop (P4-D, 3.4ghz, 1GB ram, 160gb sata) so I decided its time to give Mythbuntu a further workout.

Ordered a Hauppauge Nova-S card and slapped it into said PC and installed Mythbuntu 8.10 x64 onto it - detected the card fine, formatted /var/lib/mythtv as XFS automatically (which is *VERY* handy when deleting big files).

Had some fun getting the right LNB settings - some fields in the DVB setup are in khz and some are in mhz and for a satellite noobie like me it required a phonecall to my Dad who's extremely knowledgable about satellite stuff and some reading up on pvr.geek.nz.

I've got an old Sky dish with two LNB's (guessing they're Sky LNB's too) so from memory all I had to do was;

Add capture card -> Set to DVB (Found the card with a Conexant chipset)
Press the DiSEQ button, set the LNB to Custom
Type = bandstacker
LOF Low = 11300
LOF High = 11300

Back to capture card

Press Recording Options button, set the number of tuners to two or three (to record multiple channels at once from the same transponder)

Save the settings and get back to the Mythsetup menu

Create a manual EPG source (unless using xmltv, then set that up instead)

Then go to Channel Settings

Add a channel, set the Frequency to 12483000 and set the symbol to 22500000
Click Next and the channel scanner will appear and pick up the channels. YAY!

Go back to the channel scanner and enter the frequencies for the other transponders you want to pick up (can be found on http://www.lyngsat.com/optusd1.html)

Done!

One of the documents on pvr.geek.nz said somewhere in there (I paraphrase) 'Don't assume all fields are the same scale'; ie  some are mhz and some are khz.... this was the little light bulb that lit up and showed me the answer!

As long as the Recording Options has been set to a number higher than 1, when the channels are detected it will automatically enable multirecording.  If missed, go in and up the number and then re-detect the channels.

While playing with the channels the EPG data came down automatically and filled in the database - awesome! Didn't have to do anything.

The Nova card uses 1.4% cpu while recording & commercial flagging at the same time, and 2.2% cpu when recording two channels & commflag at the same time. Nice to have a bigger box now.

To Do:  Re-create my nuvexport scripts to be able to convert the recorded MPEG2 files to XviD and store them on my server for me. And test a frontend off this development backend. Also buy another Nova-S card so I can record multirec's from both the transponders I'm looking at.

All going to plan I will be able to retire my old backend and replace it with this big box.

Good times, good times.  Man, I'm a geek....

Other related posts:
What not to do when going away with your beloved for the weekend...
Trouble in MythLand...
Mythtv, xvid, and my PSP






Comment by Malcolm Napier, on 15-Apr-2009 21:26

Hi Dael, A useful article, thanks. Can I just check something please? You say "Press Recording Options button, set the number of tuners to two or three (to record multiple channels at once from the same transponder)" Does this mean that it is possible to record more than one channel from a single DVB-S card provided that all the channels to be recorded are on the same transponder? (I used to have a DVB-T Myth TV setup but the reception was very poor on some multiplexes. As a result I ditched the system and use a satellite PVR box. However, as more HD channels are becoming available Free-To Air in the UK I am thinking about building another MythTV box.)


Comment by Malcolm Napier, on 15-Apr-2009 22:12

Hi Dael, A useful article, thanks. Can I just check something please? You say "Press Recording Options button, set the number of tuners to two or three (to record multiple channels at once from the same transponder)" Does this mean that it is possible to record more than one channel from a single DVB-S card provided that all the channels to be recorded are on the same transponder? (I used to have a DVB-T Myth TV setup but the reception was very poor on some multiplexes. As a result I ditched the system and use a satellite PVR box. However, as more HD channels are becoming available Free-To Air in the UK I am thinking about building another MythTV box.)


Author's note by nzsouthernman, on 16-Apr-2009 23:06

Hi Malcolm
Yes, you've got it right.  As long as your host has a fast enough processor and quick enough disk you could theoretically dump every channel on one transponder at once to disk with one DVB-S card (if you set the number of tuners high enough to do that).  It's mainly the disk speed that's important as when coming off the satellite it's MPEG2 all the way and Myth just dumps the streams to disk.
The files are still .NUV named, but they are actually MPEG2 files (not the nuppelvideo format that Myth records if you have an analogue tuner).
Since I've got mine set to more than two tuners I can record Futurama on C4 between 18:58-19:32 and set a separete recording for Family Guy on C4 for 19:28-20:02. This way I have two separate recordings to choose from when watching them later even though they are one-after-the-other on the same channel, and both recordings can start/stop two min either side of the schedulled time. (Freeview NZ is pretty good at running on time, but I play it safe).
I can't get a DVB-T feed where I live so haven't tried (or looked into) Myth's HD recording with an appropriate card - I have a feeling that H.264 is going to be trying on the hardware. ie More horsepower than I have available to throw at it...
Cheers


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Dael 
Christchurch
New Zealand


This blog is mainly going to be for writing down things when I work them out so when I have to try and do it again I don't have to think too hard.  And also to comment on stuff.  Hopefully not too much rant /rant involved.

My latest finished and successful home project;

FreeNAS NAS/SAN Appliance
Celeron 2.8ghz CPU, 1GB RAM, 4x 1TB SATA drives in RAID-5 array, booting from 1GB USB flash drive


Toys in the attic;
PS3
PSP
Nokia E71-3 (Telecom XT)
iPhone 3GS (Vodafone)
MythTV separated backend with 2 DVB-S encoders & 1.2TB disk space & two frontends

Follow me on twitter; http://twitter.com/nzsouthernman