Linux FAQ about DVB-S QPSK DVB-S2 8PSK PCI PCIe USB adapters

[Smith P.]

Last days we discussed DSS goodies here.

 

[gillham]

Last days we discussed DSS goodies here.

Thanks, found it. I had this thread bookmarked. I guess the cat and the bag were separated already.

 

[zamar23]

In what format PC Cards can record sat signals?
What are advantages and drawbacks of using sat cards under Linux compare to WMC?

 

[gillham]

In what format PC Cards can record sat signals?
What are advantages and drawbacks of using sat cards under Linux compare to WMC?

Usually it depends on the software. Often it is an MPEG Transport Stream, but you can also plain MPEG.

Advantages:
You can have multiple frontends and backends all in the same system. (MythTV system on Linux) So you can have one system that records OTA and another that records DVB-S and the frontends just see recordings to watch.
Hardware drivers are standardized on the Video4Linux API. You don't have to worry about BDA versus non BDA or whatever. As long as your card is supported.
DVB-S / QAM is directly supported, not via some shim layer.
Generally there are no CODECs to round up and fiddle with constantly.
Things like SD/HD/MPEG2/MPEG4/4:2:0/4:2:2 are generally software problems and are supported without needing special hardware. You just need *fast* hardware.
You're running on a no cost Linux operating system with no cost software.

Disadvantages:
A lot more configuration required and you need to be familiar with Linux and comfortable with the command line to get it all setup. You can do a lot with the prepackaged distributions like "mythbuntu" but eventually you'll need to dig into something further.
You need to pay $20/year for program guide information.
You have to round up some dedicated hardware. MythTV doesn't really work out too well when you're dual booting the PC from Windows to Linux.
You usually need a very capable system. This can get expensive.
Also, great tools like TSReader only run under Windows.

 

[dhubsith]

In what format PC Cards can record sat signals?

The easiest way is just to record the transport stream directly. I am using a combination of dvbstream and mplayer. I have shell scripts set up that look like this for just watching:

#!/bin/sh

dvbstream -f 12140 -p v -s 30000 -v 49 -a 52 -o | mplayer -ao alsa -vo xv -fs -vf pp=lb -

and this for watching and recording both:

#!/bin/sh

dvbstream -f 12140 -p v -s 30000 -v 49 -a 52 -o | tee /mnt/sda2/$(date +%Y%m%d%H%M%S).ts | mplayer -ao alsa -vo xv -fs -vf pp=lb -

(My example is for the PBS HD channel on AMC21. Change the disk location to the folder of your choice.)

After you have it recorded, you can convert it to MPEG2 for burning on a DVD with mencoder, thusly:

mencoder /mnt/sda2/a.ts -o /mnt/sda2/a.mpg -oac copy -ovc lavc -lavcopts vcodec=mpeg2video:keyint=10:vbitrate=4000 -mpegopts format=dvd:vaspect=16/9 -of mpeg -vf scale=640:360,pp=lb,harddup

To move the dish with diseqc 1.2 I use a program called xdipo, available here: satellite

I hope this is helpful.

 

[zamar23]

Thanks guys!

dhubsith

Any difference in shell scripts for MPEG4 stream, or burning MPEG4 movie from a recorded MPEG4 TS to a DVD?

Anyone has experience in MPEG4 decoding from TS with a graphics card proc? Any extra soft is needed for that? What TV package allows that on Linux and using what options & plugins?

 

[dhubsith]

Thanks guys!

dhubsith

Any difference in shell scripts for MPEG4 stream, or burning MPEG4 movie from a recorded MPEG4 TS to a DVD?

Anyone has experience in MPEG4 decoding from TS with a graphics card proc? Any extra soft is needed for that? What TV package allows that on Linux and using what options & plugins?

My receiver card will not receive MPEG4 so I can't say for certain, but I'm pretty sure you could record the transport stream just as if it was MPEG2. Mencoder can record MPEG4, it's just a case of specifying the right codec. I've used Xvid in the past.

The thing to watch in all cases is the vbitrate, make it too low and the picture becomes blocky, set too high and it takes too much space. I am using 4000, which seems to be a good compromise.

Also, if you are recording a 4:3 video (640x480), and you want to keep it that way, you don't need to do the crop and scale. My example was for recording a HD channel.

 

[GatoViejo]

(My example is for the PBS HD channel on AMC21. Change the disk location to the folder of your choice.)

What size dish are you using? I am in the research/shopping phase at the moment and I want to make sure I can get this channel.

 

[gillham]

Anyone has experience in MPEG4 decoding from TS with a graphics card proc? Any extra soft is needed for that? What TV package allows that on Linux and using what options & plugins?

If you get an NVidia graphics card that supports VDPAU under Linux you can offload decoding. I'm using an NVidia ION based Atom board with MythTV (and mplayer as well) with VDPAU support and it easily plays back HD content through the GPU.

So far I am aware of mythtv and mplayer having VDPAU support, but I haven't really looked at anything else.

 

[gillham]

My receiver card will not receive MPEG4 so I can't say for certain, but I'm pretty sure you could record the transport stream just as if it was MPEG2. Mencoder can record MPEG4, it's just a case of specifying the right codec. I've used Xvid in the past.

All PC DVB cards should support receiving MPEG4. The card really just tunes the DVB-S/QPSK (or DVB-S2/8PSK or a different combination) signal and passes the transport stream to the software. It doesn't matter if the content inside the TS is MPEG2/MPEG4 or some other codec as it handled by the software.

Obviously not all cards will support DVB-S/QPSK and DVB-S2/8PSK modulation as the tuner and demodulator are hardware features, but those are distinct from video codecs.

 

[dhubsith]

What size dish are you using? I am in the research/shopping phase at the moment and I want to make sure I can get this channel.

I am using a 31" (80cm) Fortec Star, it's the one in my icon. My LNBF is an Invacom SNH-031. It's mounted on my (flat) roof, with an unobstructed view to the south. I wanted to use as small a dish as I could get away with because we have high winds in this area and I wanted as little load on my roof as possible. On the other hand I got the best LNBF I could.

Hope this helps.

 

[willie8605]

How does the Twinhan 1020a handle 22KHz switching and Diseqc ports? Anyone have any experience with this? I will be using it with two 4x1 Diseqc switches going into one 22KHz switch.

 

[Smith P.]

Doing OK, but each DiSEqC is different, some of them required a mod ( adding a capacitor to cut noise ).

 

[signal.quest]

Can someone please help tell me what option are available in Linux to watch 4:2:2 feeds? I am presently set up for mythtv. Does mythtv support 4:2:2? Does VDR? If VLC is the only option, can it control my Sg2100 motor? Thanks.

 

[shadetree1]

Thanks for the info, I am trying to decide weather to purchase a Geniatech Digistar 2HD or a Technotrend DVB-S2 to test a CaptiveWorks LMC-4000HD. These are the only 2 cards that support beta testing.