ATSC HDTV video problem

[foresglenn]

I have been trying for some time to resolve a mysterious playback issue with ATSC HDTV recordings. Some recorded (and live) shows play smoothly and others are choppy in VMR9 mode. Playback of all recordings is smooth in overlay mode, but this does not allow me to adjust the aspect ratio for full-screen viewing.

According to GSpot, the smooth and choppy dvr-ms files are the same resolution and bit rate (see below). Although my system is modest ([SIZE="1"]AMD Athalon XP 1800+, 256 MB, Nvidia GeForce FX 5200 128 MB, PureVideo decoder, Haupauge HVR-1600[/SIZE]) the choppy playback does not seem to be because of CPU load since it is always below 40% even in VMR9 mode.

I am using the DirectX 9.0b quartz.dll as suggested in other posts and I am not running ffdshow or dscaler.

Can anyone suggest a way I can troubleshoot this problem? There must be something different about the smooth and choppy shows, but GSpot does not provide much info on dvr-ms files other than this:

GSpot results for both smooth and choppy files:
[SIZE="1"]File Type: ASF (.WMA/.WMV)
Mime Type: video/x-ms-asf
File Length Correct
Sys Bitrate: 159618 kb/s
Created: 2007 Jun 24 18:22:15

pic 704 x 480

(Src)-->>--(A)-->[HCW MPEG-2 Video Decoder ]>--(B)-->[AVI Decompressor ]>--©-->[Color Space Converter ]>--(D)-->[Video Renderer ]

(Src)-->>--(A)-->[HCW AC3 Audio Decoder ]>--(B)-->[AC3Filter ]>--©-->[Default DirectSound Device ][/SIZE]

[sub]

Are you sure they're the same resolution & bitrate? I thought gspot didnt handle .dvr-ms files?

(Src)-->>--(A)-->[HCW MPEG-2 Video Decoder ]>--(B)-->[AVI Decompressor ]>--©-->[Color Space Converter ]>--(D)-->[Video Renderer

It's strange that the "AVI Decompressor" and "Color Space Converter" filters are listed here. Normally the video decoder would be hooked directly to the renderer. You're not running your desktop in 16 bit colour?

[Braklet]

I have significantly more hardware (Athlon 64 x2 4200+, nVidia 7900GS) and I still have to stick with Overlay mode in order to avoid all stutter on HD material.

I manually change aspect ratio in Overlay mode with the F7 key. It is true that you need VMR to automatically change aspect to the program source.

704x480 resolution is strictly SD; do you ever try to record HD channels? (A lot of them send SD out in HD resolution which caused me no end of stutter.)

I "fixed" my ATSC stutter problems by buying more hardware (upgraded from a 6600 GPU) and sticking with Overlay. I'm afraid I have no specific debugging tips because I found too much variability between program source and individual system capabilities.

What I eventually did was save known problematic recordings to a data DVD, and used that to test my setup. My biggest problems were with HD sports programming, and CBS Survivor (an SD program sent at HD bitrates with lots of moving panoramas).

I was irritated that I couldn't use VMR 7 or 9 when I got the 7900GS GPU, but I find that I don't lose much real usability with Overlay. Yes I would like the smooth, transparent menus and auto-aspect but I can get used to the former and F7 takes care of the latter.

Sorry I'm not telling you what you want to hear; I dealt with the same thing for months and found it very frustrating.

[foresglenn]

Are you sure they're the same resolution & bitrate? I thought gspot didnt handle .dvr-ms files?

Perhaps gspot does not support .dvr-ms files as you say and is not reporting the resolution and bitrate correctly. Can you suggest another tool to analyze the files?

You're not running your desktop in 16 bit colour?

I ran gspot over a remote desktop connection since my GB-PVR box only has a standard TV connected to it and is hard to read. I'll run it again locally.

Run locally gspot does not give any video graph, only the identical audio graph.

[sub]

Perhaps gspot does not support .dvr-ms files as you say and is not reporting the resolution and bitrate correctly. Can you suggest another tool to analyze the files?

Unfortunately no, not for .dvr-ms files. I know you can check the resolution by checking the pin connection properties in GraphEdit (after selecting 'render media file' from the menu, but thats not really a tool that makes it easy for users to get this info.

[foresglenn]

I manually change aspect ratio in Overlay mode with the F7 key. It is true that you need VMR to automatically change aspect to the program source.

I don't mind changing the aspect ratio manually, however Overlay mode does not seem to be able to handle the negative aspect ratio values needed to properly resize most digital TV shows to a 4:3 screen. Do you have a workaround for this? I could not find a solution in other posts.

[Braklet]

Overlay mode does not seem to be able to handle the negative aspect ratio values needed to properly resize most digital TV shows to a 4:3 screen. Do you have a workaround for this? I could not find a solution in other posts.

Fortunately or unfortunately, by the time I got GB-PVR working correctly, I moved my HTPC to a 16:9 display. The aspect modes work fine on widescreens so I haven't dug further.

I believe the aspect ratios are defined in one of the setup files (check *.ini, and *.xml). You could manipulate the values, or define new aspect modes to cycle through.

I'd try anything to avoid stutter; it was a thorn in my side far too long.

[foresglenn]

I know you can check the resolution by checking the pin connection properties in GraphEdit (after selecting 'render media file' from the menu...

Unfortunately, GraphEdit only gives this message "The requested property page can not be displayed"

704x480 resolution is strictly SD; do you ever try to record HD channels?

As sub suggested, gspot is not reporting .dvr-ms file characteristics properly nor can GraphEdit in my case, so I can't be sure of the resolution. However, I did this crude test: I opened both a smooth and choppy file in VLC. By setting the video->zoom to 1:4 I can see that the smooth file is lower resolution (probably SD DTV while the choppy file is probably HD DTV). Also, the size of short test files is 164 MB for 1 min 40 s for the smooth and 172 MB for 1 min 23 s for the choppy. So the bit rates are also different, approximately 1,640 kBs vs 2,072 kBs.

If I were able to properly resize the image for a 4:3 screen in Overly mode, I think everything would be fine. Does anyone know if this can be done?

[foresglenn]

I believe the aspect ratios are defined in one of the setup files (check *.ini, and *.xml). You could manipulate the values, or define new aspect modes to cycle through.

Yes it can be done by editing the config.xml file as described here http://forums.nextpvr.com/showthread.php...config.xml
however the required negative values do not seem to work in overlay mode.

[sub]

Unfortunately, GraphEdit only gives this message "The requested property page can not be displayed"

This is because you didnt register proppage.dll. Some downloads of graphedit dont seemt to include this - maybe they didnt know it was required.

If I were able to properly resize the image for a 4:3 screen in Overly mode, I think everything would be fine. Does anyone know if this can be done?

A 16:9 video on a 4:3 screen shouldnt require any negative values, which are the only ones that dont work on the Overlay renderer. In this case it should be using the 'LetterBox' aspect ratio, which is defined as:

<AspectRatioMode name="LetterBox" ratio="0,0.125,1,0.875" />