SageTV Community  

Go Back   SageTV Community > Hardware Support > Hardware Support

Hardware Support Discussions related to using various hardware setups with SageTV products. Anything relating to capture cards, remotes, infrared receivers/transmitters, system compatibility or other hardware related problems or suggestions should be posted here.

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 04-13-2012, 04:37 PM
Dargason Dargason is offline
Sage Aficionado
 
Join Date: Oct 2003
Posts: 423
Cablecard tuner video quality

Is there any difference in video quality of cablecard tuners?

I thought they basically just 'tuned' into a digital stream, decrypted it, and passed on the results to the software. No encoding or decoding.

I ask because it seems like my cable set-top box image quality is better than my HD300 playing a cablecard recorded show.
Reply With Quote
  #2  
Old 04-13-2012, 05:45 PM
mguebert mguebert is offline
Sage Advanced User
 
Join Date: Jan 2007
Posts: 152
Quote:
Originally Posted by Dargason View Post
Is there any difference in video quality of cablecard tuners?

I thought they basically just 'tuned' into a digital stream, decrypted it, and passed on the results to the software. No encoding or decoding.

I ask because it seems like my cable set-top box image quality is better than my HD300 playing a cablecard recorded show.
I would think it is more in the difference between the way the output is processed on the STB and the HD300.
Reply With Quote
  #3  
Old 04-14-2012, 06:52 PM
drewg drewg is offline
Sage Icon
 
Join Date: Aug 2007
Location: Mountain View, CA
Posts: 1,020
Quote:
Originally Posted by mguebert View Post
I would think it is more in the difference between the way the output is processed on the STB and the HD300.
Or even just something as simple as different settings on different TV inputs. When I had my TV calibrated, the calibrated settings at first only applied to HDMI-1 where the BD player the calibrator used was. We then copied the settings to all inputs..

Drew
__________________
Server HW: Xeon CPU E3-1270, 16GB RAM, 9TB Raid-Z + L2Arc,
Server SW: Ubuntu 12.04 x86_64, ZFS on Linux, Java 1.6.0_21, SageTV 7.1.9.1
Tuner HW: Pinnacle 800i, Pinnacle 801e USB, HDHR
Client: HD300, HD100
Reply With Quote
  #4  
Old 09-05-2012, 11:45 AM
Dargason Dargason is offline
Sage Aficionado
 
Join Date: Oct 2003
Posts: 423
I'm bumping this because I'm still not convinced the quality is the same.

Last night I was looking through some recordings and came across one that I looked at and thought "hey, that's a good picture" and it turns out it was recorded by the HD-PVR last January. Unfortunately, rebuilt my server last spring and never set up the HD-PVR because the cablecard tuner is so much more reliable.

But it's always seemed to me that there is a lot more pixelation in fast-moving scenes than there used to be. I'm really tempted to set up my HD-PVR again and try recording a show with both the HD-PVR / set-top box and the cablecard tuner. Just to prove to myself I'm not crazy.

If true, the only explanation I can come up with is that the STB renders the original source material better than the HD300. Then the HD-PVR captures the superior image produced by the STB and encodes it into a format that the HD300 handles well.

I know it's all still h.264, but I imagine there are more advanced and less advanced versions... and my provider may be outputting a version that relies on more client horsepower than the HD300 has.

Speculating even further, if this is true, then it might be possible for my server to re-encode the cablecard files losslessly into a format more like what the HD-PVR creates... and thus improve my video quality.

Am I crazy or does some of this make sense? (I suppose those things aren't mutually exclusive, though.)
Reply With Quote
  #5  
Old 09-05-2012, 11:51 AM
panteragstk's Avatar
panteragstk panteragstk is offline
SageTVaholic
 
Join Date: Oct 2008
Posts: 2,885
The stream the cable card gets should be identical to what the stb outputs unless there are picture settings on the stb. If there are, you can set the same settings on your TV to improve video quality. That should be it AFAIK
__________________
SageTV Server: Asus P5q Deluxe with 8gb ddr2, Core 2 Quad Q8300, AMD 6570. Hauppauge 2250, 1600 and AverMedia A180 for OTA HD recording. 2x Colossus for DirecTV.

HT Client: i3 530, evga h55 board, OCZ ssd, 8gb ddr3, AMD 6670. Mitsubishi HC4000, 120" DIY AT screen, Gyration RF MCE remote (awesome) X-Box 360 control for roms

Living Room Client: Foxconn a3700 with kingston SSD, 4gb ddr3, Crystal HD. 65" Panasonic VT60, Keyspan RF MCE remote
Reply With Quote
  #6  
Old 09-05-2012, 01:42 PM
Dargason Dargason is offline
Sage Aficionado
 
Join Date: Oct 2003
Posts: 423
I'm not comparing the quality of the CC tuner to what I would get if I connect the STB direct to the TV. I'm comparing it to what I get when I record the analog output of the STB using the HDPVR and then stream that recording to the HD300 for display on the TV.

In both cases, the TV is seeing output from the HD300. The only difference is whether the file was encoded by the HD-PVR or simply saved by the cablecard tuner.

Last edited by Dargason; 09-05-2012 at 01:46 PM.
Reply With Quote
  #7  
Old 09-05-2012, 02:07 PM
darcilicious's Avatar
darcilicious darcilicious is offline
Sage Icon
 
Join Date: Jul 2009
Location: Venus
Posts: 1,305
IIRC, the recording quality setting is on a per tuner basis and I'm not sure what the default is; have you made sure it's set to "best" for the CC tuner?
__________________
SageTV Server 7.1.x w/Gemstone and Plex Home Theater v1.0.10 w/PlexPass
HD-PVR w/v1.5.6 drivers / Hauppauge IR blaster / FiOS Extreme HD / Motorola QIP6200 / SPDIF+720p Fixed Output
on HP Media Center 8400F (Phenom 9500 QuadCore 2.2GHz, nVidia GeForce 8500 GT)
via Olevia 247TFHD/Onyko TX-SR606/Harmony 550/HP MediaSmart EX490 WHS w/12TB
Plex Media Server v0.9.9.5 on HP Touchsmart Envy 23 d16qd
Sonos Play:3, Connect / SimpleTV v2 / Roku 2 XS+Plex / iPhone 5 / iPad 2
Reply With Quote
  #8  
Old 09-05-2012, 02:39 PM
panteragstk's Avatar
panteragstk panteragstk is offline
SageTVaholic
 
Join Date: Oct 2008
Posts: 2,885
Quote:
Originally Posted by Dargason View Post
I'm not comparing the quality of the CC tuner to what I would get if I connect the STB direct to the TV. I'm comparing it to what I get when I record the analog output of the STB using the HDPVR and then stream that recording to the HD300 for display on the TV.

In both cases, the TV is seeing output from the HD300. The only difference is whether the file was encoded by the HD-PVR or simply saved by the cablecard tuner.
I know. What I'm saying is that some STB's have picture settings that could effect PQ when recorded by the hd-pvr where the cablecard won't have those settings.
__________________
SageTV Server: Asus P5q Deluxe with 8gb ddr2, Core 2 Quad Q8300, AMD 6570. Hauppauge 2250, 1600 and AverMedia A180 for OTA HD recording. 2x Colossus for DirecTV.

HT Client: i3 530, evga h55 board, OCZ ssd, 8gb ddr3, AMD 6670. Mitsubishi HC4000, 120" DIY AT screen, Gyration RF MCE remote (awesome) X-Box 360 control for roms

Living Room Client: Foxconn a3700 with kingston SSD, 4gb ddr3, Crystal HD. 65" Panasonic VT60, Keyspan RF MCE remote
Reply With Quote
  #9  
Old 09-05-2012, 03:01 PM
wayner wayner is offline
SageTVaholic
 
Join Date: Jan 2008
Location: Toronto, ON
Posts: 4,163
Maybe it is also an issue that the HD-300's decoder for H.264 files is giving a better, or at least cleaner looker picture than what you get from the MPEG-2 decoder? Perhaps it deals better with stuff like deinterlacing and pixelization.
__________________
Sage7 on Win7Pro-i660CPU with 4.6TB, 2xHD-PVR(connected to SA3250HD+SA4250HD-Rogers Cable), HDHR(2xOTA), HVR-1850(one OTA, one connected to SA3200 SD cable box), 2xHD-300, 8xHD-200 Extenders, Client+2xPlaceshifter and a WHS which acts as a backup Sage server
Reply With Quote
  #10  
Old 09-05-2012, 05:47 PM
Dargason Dargason is offline
Sage Aficionado
 
Join Date: Oct 2003
Posts: 423
Quote:
I know. What I'm saying is that some STB's have picture settings that could effect PQ when recorded by the hd-pvr where the cablecard won't have those settings.
Hmm... it's been a long while since I actually used the STB interface, but I can check for picture quality settings. I seem to remember not finding anything when I went looking for a way to 'fix' the output to 720p but I might be remembering a different box.

Quote:
the recording quality setting is on a per tuner basis and I'm not sure what the default is; have you made sure it's set to "best" for the CC tuner?
The quality settings don't apply to cablecard tuners... my understanding is that the card just decrypts the incoming stream and saves it to the hard disk. (I think it also re-encrypts it before saving depending on the DRM flag, but that's not relevant to this discussion.)

Quote:
Maybe it is also an issue that the HD-300's decoder for H.264 files is giving a better, or at least cleaner looker picture than what you get from the MPEG-2 decoder? Perhaps it deals better with stuff like deinterlacing and pixelization.
I'm not sure I understand which MPEG-2 decoder you mean... these scenarios are all entirely hardware decoding (in the STB) or hardware decoding in the HD-300. At least I assume the STB uses hardware decoding... it would be pretty stupid if it didn't.

But my hypothesis is that the decoder in the STB does a better job than the HD300 given the flavor of h.264 that my provider supplies.

It's got me thinking though, that it might be interesting to play around with software decoding on my PC using the 'bad' recordings to see if I can make them look better than what I get from the HD300. I think it would support the idea that the decoder makes a difference and that re-encoding the files might have some value.
Reply With Quote
  #11  
Old 09-05-2012, 06:04 PM
wayner wayner is offline
SageTVaholic
 
Join Date: Jan 2008
Location: Toronto, ON
Posts: 4,163
Quote:
Originally Posted by Dargason View Post
I'm not sure I understand which MPEG-2 decoder you mean... these scenarios are all entirely hardware decoding (in the STB) or hardware decoding in the HD-300. At least I assume the STB uses hardware decoding... it would be pretty stupid if it didn't.
I mean the hardware decoder chip in the HD300 - maybe it does a better job with H.264 than MPEG-2.

But you're right that it could be a better decoder in the STB as well.
__________________
Sage7 on Win7Pro-i660CPU with 4.6TB, 2xHD-PVR(connected to SA3250HD+SA4250HD-Rogers Cable), HDHR(2xOTA), HVR-1850(one OTA, one connected to SA3200 SD cable box), 2xHD-300, 8xHD-200 Extenders, Client+2xPlaceshifter and a WHS which acts as a backup Sage server
Reply With Quote
  #12  
Old 09-05-2012, 06:08 PM
Tiki's Avatar
Tiki Tiki is offline
Sage Icon
 
Join Date: Feb 2005
Location: Southeast Michigan, USA
Posts: 1,054
The cable card tuners capture the digital stream exactly as it is sent from the cable company. The HD-PVR re-encodes the analog signal that has already been decoded by the set top box (STB). Therefore it is impossible that the HD-PVR recordings could be better than the cable card tuners (though they may be so close in quality that they are indistinguishable).

However, there is another possibility. When using the HD-PVR, most people found it necessary to fix the output resolution of the STB (usually to 720p). The HD-PVR would then encode the recording at that same resolution. The Cable Card tuners on the other hand, do no fix the resolution - they record at whatever resolution is being broadcast.

By default, the Sage Extenders (HD300), output at a fixed resolution (unless you manually enable Native Resolution Switching). If you have your HD300 set to 720p and all your HD-PVR recordings are 720p, it doesn't have to do any scaling. Your TV might do some scaling, but most newer HDTVs have very good scalers. But, your Cable Card recordings will be a mix of resolutions depending on which channels you are recording from. It's possible that the HD300 needs to re-scale some of those recordings (1080i to 720p) and doesn't do as good of a job as the scalers in your STB and TV.

You might want to look at the recording details on some of your files and see which tuner recorded it and what the video resolution is. You may also want to experiment with the native resolution switching option in the extender.
__________________
Server: Athlon II X4 630 CPU, Gigabyte MA770T-UD3P (AM3) Motherboard, VisionTek Radeon HD4670 PCIe w/ Component output to 50" CRT Rear-Projection HDTV (Mitsubishi), Win7-64Bit (Home Premium), 4GB RAM
Capture Devices (8 tuners): Colossus (x1), HD-PVR (x1), HDHR Prime (x2)
,USBUIRT (multi-zone)
Source:
Comcast Cable
Primary Client: Server Other Clients: (1) HD200, (1) HD300
Retired Equipment: MediaMVP, PVR150 (x2), PVR150MCE,
HDHR, HVR-2250
Reply With Quote
  #13  
Old 09-05-2012, 06:11 PM
Dargason Dargason is offline
Sage Aficionado
 
Join Date: Oct 2003
Posts: 423
Quote:
I mean the hardware decoder chip in the HD300 - maybe it does a better job with H.264 than MPEG-2.
Ok, now I see the confusion. I had assumed that the feed was h.264, but I guess that's not necessarily true.

Video standards always make me feel stupid.

Quote:
The cable card tuners capture the digital stream exactly as it is sent from the cable company. The HD-PVR re-encodes the analog signal that has already been decoded by the set top box (STB). Therefore it is impossible that the HD-PVR recordings could be better than the cable card tuners (though they may be so close in quality that they are indistinguishable).
While I understand this in theory, it's only 'impossible' if you assume all decoders produce output that is equivalent, given the same input. Consider an extreme case where the STB does a perfect reproduction (given the limitations of the input stream) while the HD300 does a terrible job. In this case, it could be possible for the HD-PVR to re-encode the STB output into a format that the HD300 does a better job presenting.

Quote:
By default, the Sage Extenders (HD300), output at a fixed resolution (unless you manually enable Native Resolution Switching). If you have your HD300 set to 720p and all your HD-PVR recordings are 720p, it doesn't have to do any scaling. Your TV might do some scaling, but most newer HDTVs have very good scalers. But, your Cable Card recordings will be a mix of resolutions depending on which channels you are recording from. It's possible that the HD300 needs to re-scale some of those recordings (1080i to 720p) and doesn't do as good of a job as the scalers in your STB and TV.
I don't think was ever able to fix the STB output to 720p, but as I said, it's been a while since I looked. I'll also check the native resolution switching setting.

Last edited by Dargason; 09-05-2012 at 06:25 PM.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Using cablecard tuner with Cablevision? Opus4 Hardware Support 14 04-30-2012 01:13 PM
New Hauppauge CableCard Tuner for pre-order, shipping this month! $129 for dual tuner jptheripper Hardware Support 6 08-07-2011 12:15 PM
ATI TV Wonder CableCARD tuner for sale! Enormous The SageTV Community 8 12-11-2007 09:35 AM
ATI CableCard tuner review over at Anandtech sunray General Discussion 10 04-07-2007 11:09 PM


All times are GMT -6. The time now is 07:38 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2003-2005 SageTV, LLC. All rights reserved.