I have been using the HDHomerun for ClearQAM for a couple years now and decided to add an HDHomerun Prime to allow me to get encrypted channels in HD, too. I have a dual core processor (AMD Athlon X2 BE-2350 Brisbane 2.1GHz Socket AM2 45W Dual-Core Processor Model ADH2350IAA5DO) and 1.5 GB RAM. I have been using the on-board nvida 6150 DVI->HDMI output at 720p resolution.

When I play a local channel in 1080i (NBC for example), playback is perfect. I am using the standard decoder (ffmpeg) with xv-blit video renderer, Bob(2x) deinterlacer. It doesn't matter if it's from the HDHomerun or HDHomerun prime.

When I play a cable channel in 1080i (USA or Comedy Central for example), there is some sort of hesitation in the deinterlacing. I haven't noticed any difference in CPU usage, but it's almost as if it freezes ever so briefly on one frame, then catches back up. It is extremely noticeable in high motion scenes. At first, I thought it may have been the nvidia driver, so I have tried 173, 96, and 295 and it is the same with all of them. I have updated Xorg configuration to UseEvents 1, and nvagp 1.

I'm wondering if the solution might be to upgrade to a card that supports VDPAU, but I just don't understand why it is happening only on certain channels (and possibly only certain programs within those certain channels). The system does not appear to be underpowered, but I would appreciate any feedback which you can offer.

BTW, I am running LinHES 7.4

I had trouble with BOB and HD at one point and had to switch. You might want to try different deinterlacers. The other thing to check is the number of CPUs in the decoder options. Mine defaulted to 1 and I had significant improvement when I changed it to 2 (I have dual core, but am using VDPAU so this surprised me). Also, to rule out a buffering issue, try pausing for a few seconds to fill up the buffer and see if the problem goes away. I have a problem with 2 SD channels in recent 0.26 versions of myth where I need to do this.

_________________
ASUS AT3N7A-I (Atom 330)
TBS 8922 PCI (DVB-S2)

Have you tried playing the files on a different system to see if it is a problem with recording as compared to playback?

_________________
LINHES 8.6.1 BE/FE - MSI K9N6SGM-V with AMD A64 X2 4600+, 4GB Ram. 1.5TB WD. HDHR Prime. Nvidia GT210. MCE remote.
FrontEnd - Dell Vostro 400 3.0GHz Core2Duo NVidia GeForce210. MCE Remote

Thanks for the feedback guys. I spent over an hour last night trying (unsuccessfully) to track down the problem. I thought maybe it was frequency scaling, so I disabled that and there was no improvement. I tried selecting 2 CPU's in the decoding section and did not see an improvement. I know there is a message in the backend log that is related to the buffering and I did not try to pause it last night, but I know I have attempted to watch recordings while they are recording and even if I start 5 minutes behind it didn't seem to make a difference. I have noticed that even within these stations, it seems to be certain programs that do it. Specifically, TV series (non-live) and Movies. For example, I have seen it with several movies on Comedy Central and USA, I first noticed in on USA with the TV Show "Burn Notice". While I was trying to sort this out, NCIS happened to be on and it did it with that, too. There have been some movies on Comedy Central where I have noticed it, but when something like "The Daily Show" or "The Colbert Report" is on, I have never noticed it. I'm wondering if Comcast is compressing some content and that is contributing??? I forgot to mention I tried Yadif (2x) and GreedyMotion (2x), but they would begin stuttering after 10s or so. I also tried using OpenGL instead of ffmpeg, but it only produced a black screen.

This is the only LinHES system I have. I have one other Linux machine, but it is connected to a monitor and not an HDTV. In fact, it probably does not even have mythtv 0.25 on it. I will see if I can get it configured and test whether it is working.

Are there any good deinterlacers that I could try that are not going to be any more processor intensive than Bob?

I don't know if this is a new issue with my system or if it has always been this way, because I have only had the cable channels in HD for a week. I never have and still do not see this phenomenon on the local HD channels. Craziness...

I have slightly more to add. I recorded Burn Notice tonight (2 hour long episode). I started watching from the beginning about an hour after it started. Playback was great until the first commercial break. Then I skipped forward past the commercials and the it became fudged again. I exited playback and selected it again and playback was great again. I also noticed that as it was recording, the total length of the recording was short (maybe 80-85% of the actual length). Once the recording finished, it correctly showed the total length as 2:01 (must have "jumped" when the recording ended). However, when I got to the end of the show, it said it was only at 1:41. If I start over and skip to the end, it stops at 1:41 of 2:01. I'm going to run optimize_mythdb.pl and see if maybe something is corrupt in the database, but I am just grasping at straws.

In the event that it could possibly be related, when I view live tv recordings in mythweb, there are 4 "phantom" recordings between July and December that keep coming back if I try to delete them. They do not show up on the mythfrontend, though.

Additional Note: Poking around the mythconverg database, I noticed the following in recordedprogram:


I'm no doctor, but I would imagine all those "DAMAGED" lines can't be a good thing...

The investigation continues. I think I have finally found the cause of the problem, so hopefully that is half the battle (or more).
When I play back this recording, in the frontend I can select "playback data" where it shows resolution, framerate, buffer info, etc. Well, when the show is on, the FPS shows 23-25 (presumably 24?). Some of the commercials will show the same thing. Other commercials will be at 29.9 (presumably 30?). Anyway, I believe that the issue occurs when the FPS changes. I have found the following and may see if any of these ideas help:
http://www.mythtv.org/wiki/User_Manual:JudderFree

That wouldn't explain the incorrect times being reported by frontend, though. In the frontend I also changed it from Interlaced to "Detect" and it detected Progressive while the show was playing. I did not notice any interlacing. I also did not notice any "judder".

While writing this thread, I also found the following on google which seems to closely match my problem:
http://www.gossamer-threads.com/lists/mythtv/users/388886

I don't have time to read it all at the moment but hopefully it will shed some light.

Just as an FYI, movies and some TV shows are shot and shown at 24 fps. TV can be shown at 29.997 fps and 59.997 which is holdover from when they switched to Color TV and the bandwidth wasn't wide enough for a full 30 fps.

_________________
My System

An experiment to try -- When you hit that commercial break, skip forward far enough into the restarted show so that a you can hit "skip backwards" once and still be in the show. Does that get you smooth playback?

_________________
Marc

The views expressed are my own and do not necessarily reflect the views of my employer.

Does it sound anything like this problem?
viewtopic.php?t=21934

_________________
My System

I don't know if my vision has just gone blurry or what, but I am not seeing the judder now that I am playing back the completed recording. The time is still off, though. I'm starting to wonder if the judder only occurs when it is playing back at the same time as recording (Live TV / Watch Recording before it has completed).

matt, I can't really say if it is related to that problem. It is almost a mild form of stuttering. It's like it either misses a frame or duplicates a frame when it shouldn't and the worst case scenario is it is panning and rather than being smooth from one side to the next, it hesitates just enough to give it a jerkiness.

I thought it best to mention that I am going to be away from my DVR until after Christmas now, so I will pick this back up then. I hope everyone has a Merry Christmas and I appreciate the help you have provided me.

I've opened a ticket with mythtv because it's only happening with Live TV or if I am watching a recording while it is still in the process of recording (even if I am an hour behind "live"). Playback is fine if it is a completed recording. It also only happens with 24fps programs on 1080i.
Here is the ticket:
http://code.mythtv.org/trac/ticket/11304

Over the course of all of this, I have had 3 different nvidia drivers installed and have not noticed any difference. By default, 173 was installed. I also had 295 installed and when that didn't improve it, I switched to 96 and have been using it the most. I vaguely remember 96 being the best driver for the 6150 several releases ago. I thought I would bring that up in case there might be any known issues with any of the nvidia drivers on the 6150 (or if anybody can explain to me why all 3 are still maintained).

The problem started with your new cablecard tuner correct? Are the cable card recordings different than QAM recordings? I know that for example my OTA recordings are always *.mpg files and the size of the file depends on the quality of broadcast. Are the scrambled channels different? Are the Scrambled channels taxing your HD more some how? When you mention that you only have issues when you playback something currently recording it makes me think of HD throughput. Also do you have Commercial detection scheduled to start as soon as the recording starts? If you do try telling it to wait until the recording is done. I was looking for your systems specs could you list them please.

_________________
My System

As an FYI, I have both a clear QAM HDHOMERUN and an HDHOMERUN PRIME that uses a cable card. My system is a dual core atom + ION. I don't have any playback problems.

Do you run commercial skip? That process is CPU intensive. Problem more important -- it used to wait until the recording was done before it would start running the commercial check, but in a more recent MYTHTV release they designed it so that it could run in parallel with the recording...

_________________
Marc

The views expressed are my own and do not necessarily reflect the views of my employer.

I think that they are recorded the same way. After all of the time I have spent trying to diagnose this, I feel 90% sure that this is related to shows/movies that are 24fps, but I am not sure why it manifests itself on live/recording tv only. There seem to be a lot of programs on cable in HD that are broadcast this way, but I have not seen one on local HD channels.
System specs:
ASUS M2NPV-VM Motherboard (on-board DVI video to HDMI & on-board audio optical TOSLINK)
AMD Athlon X2 BE-2350 Brisbane 2.1GHz Socket AM2 45W Dual-Core Processor
2.5 GB RAM (512MB shared with video)
No PCI/PCI Express cards. Used to have a PVR500, but removed that after setting up the HDHomeRun.
USB Streamzap IR receiver
USB Keyboard/mouse receiver (plugged in but rarely used).

I have cpu frequency set to ondemand, but I have tried setting it to performance and it did not improve. When I am playing back the video each core is maybe 60-75% when it is ondemand at like 1 GHz (performance is 2.1 GHz).



I only have one program that is set to auto-flag commercials and is late night, so it has not been part of my sample set. It is on cable and I have not noticed any problems with it, but I have not watched it live and do not know if it is 24fps or 30fps (or 720p 60 Hz).

What settings are you using for your display? Mine is set for 1280x720 @ 60 Hz. I don't know what my TV is capable of, but do you think that it could be improved by checking the box for separate video modes for GUI and TV Playback from the mythtv wiki link I posted earlier? I looked briefly, but my X settings must only allow 60 Hz, so I would have to do some more fiddling. I've never seen this referenced before, so I didn't know if it is widely used or not.

I have two systems:

-- Single core ATOM + ION connected to a 1080p TV.
-- Dual core ATOM + ION connected to a 720p TV.

I am driving full resolution on both units, but I am using ION's hardware assisted video decoding. The deinterlacing is also hardware based.

We're all thinking CPU, but there is another angle. Are you disk drives local or network attached? In general, tell us more about your storage setup.

_________________
Marc

The views expressed are my own and do not necessarily reflect the views of my employer.