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HDTV 5500, Comcast Digital HD, and MythTV
PostPosted: Sat Nov 18, 2006 1:14 am Reply with quote
brian_b
 
Joined: 18 Nov 2006
Posts: 9




I'm a Comcast Digital/HD subscriber in the Fresno, CA area. I got myth 0.20 up and running via Firewire to the DCT6200 that Comcast gives out as their HD STB. It tuned 85% of my channels (pretty much all but in-demand, PPV, and HD versions of subscription channels). Probably ~150 digital channels, and nearly 100 analog channels total.

Firewire just wasn't reliable enough.

So I decided to sink a bit of money into it, and got a pcHDTV 5500 card, since it was recommended for direct Digital Cable tuning - which would leave my settop box free to watch TV while Myth works on my computer with it's own tuner as a DVR. The driver installed fine, Myth picks it up fine. Scanning channels, I get 210 distinct QAM256 channels (which is pretty darn close to what my subscription has).

Some other research on these forums reveal that Comcast strips out all channel/program info, so all 210 channels show up as "Unknown". No big deal. I sat down for 3 hours, going through them in Live TV mode, and editing the channel information.

Out of the 210 channels, only 31 had any signal, and of those 31, only 22 of them actually matched up to anything on my subscription list (8 mystery or bonus channels, depending on how you look at it). The other 177 channels were black background with a small blue square in the lower right hand corner. (I didn't bother with xine, mythtv's live recording is doing the same feature and I wouldn't watch live tv on the computer, just using it as a DVR).

I understand that QAM-capable tuner cards can't decode encrypted (5c) digital channels. I also was under the impression that Firewire couldn't pass these channels through either. So ~150 channels via firewire, and only 31 via the 5500, it doesn't quite add up.

Also interesting to note, is that mythtv's scanner finds 210 QAM channels, linuxtv's dvb apps scan detects 243 QAM channels, and the dtvscan util from here finds 252. None of them list any signal strength or channel info, but from what I can tell, this is a bug with DVB support in the 2.6.18 kernel, and Comcast stripping all program information.

I could get all channels if I use the CATV or S-Video output on the DCT6200 (assuming I can stumble upon getting NTSC working in myth), set the 5500 up to just record NTSC Ch3, and use 6200ch (or an IR blaster, but that would be even more money...) to change the channels; I get all my subscribed channels (even encrypted ones), but I lose HD (which half of the reason I went with the 5500), still have to go via the STB (which was the other half of the reason I went with the 5500), and I could have just gotten a $30 capture card rather than a full-blown QAM-compatible HD card - so I'd rather not do this.

For the purposes of troubleshooting, I've connected the tuner card straight to my cable outlet, with no other devices or splitters on my cable line. I'm running Fedora Core 5, Kernel 2.6.18.2239, with the latest 5500 drivers compiled and installed from pcHDTV's site. Myth 0.20-144 from the atrpms distro.

Any advice on getting this 5500 working? I'm asking the Myth folks their opinion via their mailing list as well.
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Related, but not helpful to you question...
PostPosted: Tue Nov 21, 2006 10:09 am Reply with quote
skow
 
Joined: 27 Apr 2006
Posts: 14




Unfortunately, I won't be of much help since I don't have a 5500 or Digital Cable... I do have a pair of 3000s that I record OTA HD without issue though.

At one point in time I was considering a similar setup (MediaCom Digital/HD + MythTV + Firewire). What kind of reliability issues did you find with firewire?
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PostPosted: Tue Nov 21, 2006 4:00 pm Reply with quote
brian_b
 
Joined: 18 Nov 2006
Posts: 9




Since posting, I've learned from the MythTV mailing list, that the encryption used on digital cable, and 5c re-encryption used on the firewire retransmission from the cable box, are different animals. Turns out that 90% of my cable subscription is indeed encrypted, and I'm just getting the weather channels and OTA HD rebroadcasts. At least the NTSC portion works great (once I upgraded to 2.6.18-1.2849.fc6 and used the built-in DVB driver rather than compiling my own), so it's not a total loss - NTSC plus the few HD channels are better than nothing.

I running it as a dual tuner setup now in MythTV, the pcHD5500 as my primary for NTSC and those few HD channels, and the firewire connection as a secondary.

Ironically, after installing the tuner card, my firewire has been rock solid (possibly because the firewire card is in a different PCI slot), and so far I've not had a single problem with it.

Before that, I had banged my head against the wall trying to keep firewire working correctly. Occasionally it would miss a digit while changing channels, but more often than not, it would change channels, then just stop getting data - requiring unplugging the firewire line, waiting a few seconds, and replugging it in to hard reset the connection (software resets wouldn't work). I tried half a dozen priming methods to try to jumpstart data after a channel change, and just couldn't get anything reliable with any of my firewire chipsets (3 total). In MythTV, I was probably only getting 33% of my scheduled recordings to actually record correctly, and live tv would break more often than it would work.

Firewire picture looks fantastic, the setup was 10x easier than the tuner card, the cable box takes out all of the overscan and gets almost all of my subscribed channels. My cable box has a wierd problem where it scales the picture incorrectly (almost looks like it's trying to zoom a 16:9 down to 4:3, so a large chunk of the right-hand side of the picture is missing), but that's the cable box and not the firewire. Digital and HD content look pristine and record smoothly.

If you can get a reliable connection (and from all accounts, it seems to be hit or miss depending on your firewire chipset, your cable box, and the phase of the moon), and don't mind using your cable box as a tuner, I'd recommend firewire over a tuner card in a heartbeat.
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unencrypted channels
PostPosted: Tue Nov 21, 2006 10:30 pm Reply with quote
eneilsen
 
Joined: 21 Nov 2006
Posts: 3




Can you list the HD channels that are unecrypted using comcast.
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PostPosted: Wed Nov 22, 2006 12:09 am Reply with quote
brian_b
 
Joined: 18 Nov 2006
Posts: 9




KGPE (CBS)
KFRE (CW)
TNT-HD (no sound)
KFSN (ABC) (3 different HD transmissions of this same channel)
KVPT (PBS)
KMPH (Fox)
KSEE (NBC)
InHD
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what firewire chipset did you use
PostPosted: Wed Nov 22, 2006 5:17 am Reply with quote
john.anthony.brown
 
Joined: 31 Oct 2005
Posts: 17




I'm thinking of giving the firewire approach a try.

What firewire PCI card are you using?

What software did you need to config and kernel modules did you need?

Thanks!
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5C re-encryption
PostPosted: Wed Nov 22, 2006 9:43 am Reply with quote
skow
 
Joined: 27 Apr 2006
Posts: 14




Do you happen to know what the purpose of the 5C re-encryption is? Particularly, what kind of device is capable of consuming that signal? I certainly wouldn't mind using a cable box as a tuner if I could get better reception and a wider variety of channels... If most of them are unusable due to being re-encrypted it would not seem very useful.

Thanks!
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PostPosted: Wed Nov 22, 2006 3:55 pm Reply with quote
brian_b
 
Joined: 18 Nov 2006
Posts: 9




On my service, 5c encryption only applies to HBO-HD, InDemand content, and a few PPV channels (I still get SD HBO channels via firewire) - so I'm guessing it's just a way to keep people ripping HD versions of "free-with-subscription" content, although it may change from provider to provider.

So, as far as I understand - digital encryption requires either firmware or a smart card to "unscramble" the ATSC signal off the line. 5c encryption goes one step farther, and prohibits retransmission after the ATSC signal as been "unscrambled" by your tuner. I am quite possibly entirely wrong on this though, as I'm still learning about all of it.

As far as setting up Firewire, the best guide I've found so far:
http://www.mythtv.org/wiki/index.php/FireWire

Fedora Core 6 cames with the required libs pre-installed, Core 5 they were available via yum and installed easily - other distributions I have no idea.

I'm currently using a NEC-based PCI card from Adaptec. My asus onboard firewire was junk and didn't work at all (VIA chipset). I also had a Agere-based PCI card (generic ieee1394 card) that worked, but not as well as the Adaptec card does. I've heard of people getting good results with the on-card firewire port on Soundblaster cards too.
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PostPosted: Fri Nov 24, 2006 7:19 pm Reply with quote
Malibyte
 
Joined: 28 Aug 2006
Posts: 46
Location: Simi Valley, CA, USA




Brian -

I have a very similar setup to yours - I have a Firewire connection to a DCT6200 which I'm trying to get working, and a 5500 card, running Myth 0.20a under Mandriva 2006 (x86_64) and 2.6.18rc5 (Linus's generic kernel, custom-compiled). I'm on Time Warner Cable with digital/HD packages; only "premium" channels are the HBO group.

I'm not all the way through the Firewire setup, so can't say yea or nay on it yet.

However, with the 5500, I can ONLY get the crappy NTSC channels - nothing else. I can't get it to find ANY QAM channels.

How do you have your 5500 set up under Capture Cards in mythtv-setup?
Also, do you have the input to your 5500 card coming from the raw cable or from the output of the 6200 box?

Thanks
Bob

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PostPosted: Fri Nov 24, 2006 8:29 pm Reply with quote
brian_b
 
Joined: 18 Nov 2006
Posts: 9




I'm still playing with the setup a little bit in Myth, but for now:

5500 and 6200 each have their own cable line.

Under Myth Setup, I have 2 capture cards defined: Firewire and DVB

I have 3 channel sources (all using the same Zap2It account info right now, but I am thinking it would be better if the firewire card and the DVB card each had their own account): One for Firewire (all channels 1-935), one for NTSC only (channels 1-99) and one for ATSC only (channels 101+).

Under Input Connections - tie the full lineup to the firewire input, the NTSC to the Analog Television input of the 5500, and the ATSC to the DVB input of the 5500. You will still need to do a channel scan for both of the 5500 inputs, but Firewire will be good to go once you import the channels from the listings.

I found my QAM channels using QAM256 and Cable-High frequency table. A scan in Myth found over 200 (which matches the subscription), and there was no station identifying data with the channels (thanks Comcast =( ) so I went through by hand, using the live TV viewer in Myth and marked all the encrypted channels using the channel editor - as well as put in what data i could for the very few channels that actually worked. Only a very few ended up being non-encrypted (basically anything you could get with a OTA HD antenna). I hear this varies from provider to provider though, so you might have to just test every combination, or it's possible that TW uses a different broadcast frequency as well, which would be a pain to figure out. http://www.cisco.com/en/US/products/hw/cable/ps328/products_case_study09186a00800add40.shtml seems to indicate that TW is using QAM256 at least, but doesn't hint at the frequency range. You can also try http://www.mythtv.org/wiki/index.php/Working_QAM_cable_layout, which may have some information that is useful.

It is possible to use the cable output (or S-video or composite output) of the 6200, I did test it - if you set the capture card to stay on Channel 3, and use an external channel changer (ie: 6200ch or an ir blaster), it will use your cable box as a tuner, and you will get every single channel in your subscription, but everything will be downconverted to 480i, and if you do decide to use firewire as a second capture source, the two sources will conflict on channel changes (since they will both try to use your 6200 as a tuner).
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5500 analog and HD recordings
PostPosted: Sun Nov 26, 2006 12:23 pm Reply with quote
eneilsen
 
Joined: 21 Nov 2006
Posts: 3




I'm in the market for an analog / HD capture card for myth. I currently have a Hauppauge WinTV and comcast basic. I'm thinking about getting the 5500; however, from my understanding the 5500 has an audio out jack that connects to the sound card and is used for analog recording. My current WinTV card uses this approach as well. So if I were to get the 5500 I'm assuming I would have to remote the WinTV card or not use the 5500 analog recording. I have a few questions about the 5500:

1. Can it record HD QAM (unencrypted) and analog at the same time?

2. With analog is there anyway to record a show w/o using the cable that goes between the 5500 and the sound card?

3. In analog does it record stereo or in mono?

4. When you aren't watching or recording anything and your speakers are turned on can you hear any sounds? It appears that my capture card once turned on doesn't turn off. It continues to send from the capture card to the sound card's line in. Then in turn the sound cards sends that to my speakers. It's really faint, there isn't any amplification. I'm not sure if I have something setup incorrectly, I wouldn't be surprised if I did. Have either of you experienced a similar problem with the 5500 when recording analog channels?
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Re: 5500 analog and HD recordings
PostPosted: Sun Nov 26, 2006 2:43 pm Reply with quote
brian_b
 
Joined: 18 Nov 2006
Posts: 9




eneilsen wrote:

1. Can it record HD QAM (unencrypted) and analog at the same time?

2. With analog is there anyway to record a show w/o using the cable that goes between the 5500 and the sound card?

3. In analog does it record stereo or in mono?

4. When you aren't watching or recording anything and your speakers are turned on can you hear any sounds? It appears that my capture card once turned on doesn't turn off. It continues to send from the capture card to the sound card's line in. Then in turn the sound cards sends that to my speakers. It's really faint, there isn't any amplification. I'm not sure if I have something setup incorrectly, I wouldn't be surprised if I did. Have either of you experienced a similar problem with the 5500 when recording analog channels?


1) No, one or the other. It will try to show both if you tell it to, but you will just get static

2) The card does have an on-board audio input (cx88), but the drivers are not supported at this time. I was able to get it to work once, but the audio quality was unacceptable. See http://www.pchdtv.com/forum/viewtopic.php?t=1466 for more details. It looks like someone is working on it at least.

3) Analog will record in stereo (assuming your sound card is set up to record as such)

4 This depends on your sound card as well. With most, if the mixer is set up appropriately, you will not get audio playing at the same time as you are capturing. This may vary from sound card to sound card.
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PostPosted: Sun Nov 26, 2006 3:54 pm Reply with quote
Malibyte
 
Joined: 28 Aug 2006
Posts: 46
Location: Simi Valley, CA, USA




OK, I'm getting ready to start popping Valium. This setup is really beginning to piss me off.

I have two "capture cards" set up - DVB (which supposedly does QAM64/256 as well as analog (latter via the v4l drivers)) - and the firewire via the DCT6200 box; I have a SB Audigy sound card with a Firewire input on the PC end.

Input is via the firewire and the raw TW digital cable.

OK....I can get the 5500 to do a channel scan with dtvscan -q. Channels 2 through 49 or thereabouts come up as VSB_8; everything higher ( through 158 ) comes up as both QAM-64 and QAM-256. My cable subscription includes channels to over 500, but the 5500 can only find signals up to 158.

When I try to do the channel scan through mythtv-setup:
For the analog (v4l) "Television" input - it just sits there and does nothing.
For the DVB:0 input - it does find some channels between 78 and 118, nothing higher, and nothing that seems to match Zap2It's channel listings for this area. During the QAM-256 scan, it reports signal/noise of over 95% for all the channels it finds, is able to lock on, but the signal-strength bar never registers anything above zero.

At one point I was able to scan in the analog channels ( 2 through 78 and 98 ) when I also had a third "capture card" enabled ("V4L Analog"). Since brian_b has his setup configured without it, and the DVB option has both digital and analog options, I have not configured the V4L Analog option again. I now do not have analog channels at all.

Also, I can change channels on the cable box with the Firewire (using the 6200ch utility) - but that's it. I don't have test-mpeg2 and can't find it anywhere for download, so I can't tell whether or not I can get any actual content through it.

Does anyone have a list of known working mythtv-setup settings for the 5500 card and TW Cable (Comcast is probably very similar, since they seem to be one entity now)? Sorry to have to ask, but this damn thing has me going bald quickly. I'm wondering if maybe I do have Myth set up correctly and it's the @#$%^&! cable company and their @#$%^&! encryption scheme that has everything all f'ed up here.

Sorry for the newbie request, but I don't see getting this running without some help from those who've done this before.

I even tried re-initializing the database, but that didn't work either. I am too far out on the fringes to get any decent OTA HD signals, so that option's out; even if I weren't, I really don't want to put up an outdoor antenna anyway.

Thanks for the help, in advance...Bob


Last edited by Malibyte on Sun Nov 26, 2006 5:23 pm; edited 1 time in total

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PostPosted: Sun Nov 26, 2006 4:45 pm Reply with quote
brian_b
 
Joined: 18 Nov 2006
Posts: 9




Signal strength is bugged in the latest kernel drivers. I'm hearing they will be fixed again in the 2.6.19 version. For the moment you can mostly just ignore it. (There were some posts here on the forums regarding it, but I can't find them at the moment, sorry)

The way QAM works, is that each channel has multiple MPEG streams. The number of streams varies depending on the bandwidth - a channel can carry half a dozen or so HD channels, or about 25 digital SD channels, or 50+ music stations (those numbers are relative approximations, not specifics).

Your cable box maps those streams to channel numbers - you really don't have "Channel 534", its really QAM256 Channel 78, Stream 4 (again, just an example). Myth will do the same thing in the channel editor once you get it all set up, but that initial setup is a royal pain.

Some service providers include data with the MPEG stream (called EIT) that tells some channel identification - but not all providers do this (mine does not). MythTV can scan EIT data if it's available. If it's not available, you have to do it manually, go through in the live tv viewer, and look and see if you can match the channel up to your subscription. Pressing E while in Live TV in Myth opens a channel editor, so you can re-name the channel while your watching it. Cable companies often don't use the EIT data, since they can control the mapping in your cable box, and they know what they are putting where.

Expect a lot of channels to be encrypted (ie: You get a channel lock, and scan reports it, but when you go to view it you don't get any picture). Not much you can do about that I'm afraid.
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PostPosted: Sun Nov 26, 2006 8:57 pm Reply with quote
Malibyte
 
Joined: 28 Aug 2006
Posts: 46
Location: Simi Valley, CA, USA




brian_b wrote:

The way QAM works, is that each channel has multiple MPEG streams. The number of streams varies depending on the bandwidth - a channel can carry half a dozen or so HD channels, or about 25 digital SD channels, or 50+ music stations (those numbers are relative approximations, not specifics).

Your cable box maps those streams to channel numbers - you really don't have "Channel 534", its really QAM256 Channel 78, Stream 4 (again, just an example). Myth will do the same thing in the channel editor once you get it all set up, but that initial setup is a royal pain.

Some service providers include data with the MPEG stream (called EIT) that tells some channel identification - but not all providers do this (mine does not). MythTV can scan EIT data if it's available. If it's not available, you have to do it manually, go through in the live tv viewer, and look and see if you can match the channel up to your subscription. Pressing E while in Live TV in Myth opens a channel editor, so you can re-name the channel while your watching it. Cable companies often don't use the EIT data, since they can control the mapping in your cable box, and they know what they are putting where.

Expect a lot of channels to be encrypted (ie: You get a channel lock, and scan reports it, but when you go to view it you don't get any picture). Not much you can do about that I'm afraid.



Brian - thanks for that info...I guess I will have to try to match them up manually - if I can find any that work.

If almost all of them are encrypted....stupid question....why are all of us doing this (trying to get this setup to work with cable) in the first place?

My whole goal was to create an HD-capable DVR system which would also function as a media server for my whole network (music, non-broadcast video files, etc. as well as the ability to watch recorded programs on machines elsewhere in the house), and be useful as a PC as well (with a 61" monitor Very Happy ). I suppose I can still "sort of" do this if I just pipe the S-Video output of the cable box into the 5500 card - but then I get no HD, and can't watch one program on the TV while recording another on the Myth box. I suppose that I could have spent $900 (+ $13/month) on a Series 3 TiVo box and gotten almost what I wanted....or rented a DVR from the cable pukes...sigh.

Confused

Also, I'd like to try and test the Firewire input. How do I get Myth to use it as the primary tuner?

Thanks...Bob

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HDTV 5500, Comcast Digital HD, and MythTV
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