Dropping frames with Win 7 and HD?

[shewhorn]

Hi,

New to SageTV. I just built a new machine and I'm having trouble with HD playback dropping frames. I saw a post on the frame buffer but the OP indicated that playback was smooth after pausing for a few seconds. This is not the case with my system. Here's the details:

OS - Windows 7 RC (build 7100) 32 bit
Motherboard - Gigabyte GA-E7AUM-DS2H (NVIDIA 9400 chipset w/integrated graphics).
Processor - Intel e5200
HD - 1 Terabyte WD Green
Encoder - Hauppauge 1800
RAM - DDR2 800, 4 gigs

I'm running all the latest drivers. For the 9400 chipset I downloaded the most recent build for Win 7 32 bit from NVIDIA's website (186.18 released on June 18th). For the Hauppauge 1800 I'm running the drivers from the WinTV v7 install (the current release drivers and the beta drivers from the support page of the 1800 don't seem to support ClearQAM but the drivers included in the WinTV v7 distribution seem to be doing the trick).

I am running the current release version of SageTV.

The integrated chipset supports all the good stuff (hardware support for h.264, BluRay, DXVA, blah blah blah).

So, HD playback isn't all that it should be. Specifically it looks like frames are occasionally getting dropped. This is especially noticeable in scenes where the camera is panning across a complex scene (and as such the compression algorithms don't have as much to compress).

I don't believe I should be having any trouble here at all. Even on the highest quality recording setting playback is inconsistent and sometimes I'll get an occasional freeze. I've noticed that some folks have run into a frame buffer issue but that doesn't seem to be the case here as performance is the same even after I've paused playback for a few seconds.

I've tried different recording qualities (regardless, even at a low recording quality FRAMES shouldn't be getting dropped), different settings for the codecs, hardware acceleration on/off, etc. Processor utilization whilst recording off of both the standard def and HD inputs is negligible (around 20% to 25%), while the 1TB WD Green drive isn't the fastest on the planet, the bandwidth required for this application isn't even coming close to what it's capable of (and fwiw the drive is formated with 64k blocks).

At this point I'm not really sure what I should be trying to diagnose. The hardware should be more than adequate for this application. I'm not sure if I should be looking at hardware or software though. Is Windows 7 just too young (it seems as if other folks have it working though)? I tried Windows Media Center but it couldn't see the 1800 (I wanted to see if it was perhaps an issue with Sage). I tried WinTV but it couldn't see the ClearQAM input. SageTV is the only app that seems to work.

If anyone can point me in a direction it would be greatly appreciated.

Cheers, Joe

[shewhorn]

Just to add... I'm seeing dropping frames in SD as well although it isn't nearly as obvious as it is with HD.

Cheers, Joe

[alfi33]

Well, first of all, the recording quality settings don't do anything when you are recording a digital feed. Since the feed is already digital it doesn't need to encode anything. So when capturing Clear Qam, the hardware encoder on your HVR-1800 isn't doing anything.

I have zero experience with Windows 7, but typically the first things I'd experiment with when you have this type of symptom are your video decoder selection and your video renderer (Overlay, VMR, or EVR). What do you currently have these set at?

You mentioned what your CPU utilization is when recording. What is it during playback?

[shewhorn]

Originally Posted by alfi33

Well, first of all, the recording quality settings don't do anything when you are recording a digital feed. Since the feed is already digital it doesn't need to encode anything. So when capturing Clear Qam, the hardware encoder on your HVR-1800 isn't doing anything.

Good to know. You would think they'd disable the option to set the quality on a digital only input? It's misleading to have it there. I figured they were just re-encoding it at the chosen level of compression (in much the same way you can open say... a level 12 JPEG and save it as a level n JPEG reducing the file size by resaving it at a higher compression ratio).

I have zero experience with Windows 7, but typically the first things I'd experiment with when you have this type of symptom are your video decoder selection and your video renderer (Overlay, VMR, or EVR). What do you currently have these set at?

Encode is set to EVR
MPEG2 decoder is set to default
MPEG4 is set to DirectShow
Dscaler Deinterlacing Filter is disabled
Audio Renderer is set to Default
MPEG2 Audio Decoder is set to default

Also of interest... in the advanced tab I have 3D Hardware Acceleration, and FSE mode enabled.

I can report that I'm getting much better playback of HD content with FSE mode enabled (including previously recorded HD content which verifies (as you suggested) that this is a playback issue and not an encode issue as the card merely needs to grab the stream and save it to disk, no real crunching needed on the input side).

You mentioned what your CPU utilization is when recording. What is it during playback?

The CPU utilization quoted was for simultaneously recording on both the SD input and the HD input whilst watching the HD input timeshifted (paused playback of the live feed for about 30 seconds and then pressed play). After enabling FSE mode with the above configuration (recording two streams and playing back one) processor utilization is about 15% (it oscillates between 10% and 20%).

I think the FSE mode was the key.

The next problem to solve is why some ClearQAM streams drop out. Sage is reporting a signal strength of 94% which I think would be enough but I'm still getting pixelization. What's thrown me for a loop is that it's only on certain channels, specifically WLVI DT and WHDH DT. I thought it might be because they were at higher frequencies and possibly experiencing more loss as a result however... I've found channels at higher frequencies that show a signal of 100%.

Is the Hauppauge 1800 known to have a really finicky HD tuner? I did replace a splitter taking it from a 5 way to a 4 way and using the strongest output for the DTV input and that seemed to improve things a bit (signal strength up from 88 to 94%) in terms of image stability but it's still not perfect. My STB doesn't seem to care either way (Scientific Atlanta HD4250).

Cheers, Joe

[alfi33]

I have not had any issues like this with my 1800. I only used my 1800 for Clear Qam for a short time but I had no problems with it. Now I just use it for OTA ATSC and it's been great for me with that as well.

I have heard some people complain that the 1800 is kind of a picky tuner. Some people have problems with the signal strength being too weak and others have problems with it being too strong. So you have to find that sweet spot right in the middle. Many people have used amplifiers to strengthen the signal or multiple splitters to weaken it. Have you tried it without using a splitter at all?

Also, I'm not sure how useful the signal strength indicator thing within Sage is. I've never felt it gave me a very accurate idea of where I was at. Have you tried the Hauppauge Digital Signal Strength Indicator?
http://www.hauppauge.com/site/suppor...t_hvr1800.html
(Click on the 'Accessories' Tab.)