ATSC USB TUNER playback trouble

dvasco · Post by **dvasco** » Wed Feb 25, 2009 7:26 am

I have a USB ATSC tuner that works fine but playback of the recorded video suffers audio and video stuttering on the higher resolution recordings. I have an Athlon 64 X2 5000+, Gigabyte 6100 mobo, Asus EAH3450/HTP/512M, and WinXP. Should I be able to get fine playback on all of the recordings with what I have?

teststrips · Post by **teststrips** » Wed Feb 25, 2009 10:10 am

I would def think that your machine would have enough oomph to play back these files.... I believe ATSC is just mpeg2 - so make sure you have a decent mpeg2 decoder... I really like the Nvidia PureVideo codec (you don't have to have an Nvidia video card to use it). Try to download the free trial to see if that works for you.

I had two other issues on a slower machine before I got my playback perfect.. first was signal from my antenna... my antenna wasn't aimed correctly, and I had drop-outs in signal, etc which I was blaming on my PC, but it was actually the signal strength being too low.

I also had a problem with one of my hard drives.... it had been originally formatted fat32, and then upgraded to NTFS... The partition was set up to have 512 byte Allocation Unit Size (Cluster size). Cluster size determines the smallest slot that you can store data in. Using a small cluster size will save (some) space on the disk, but will slow you down because you have to keep track of all of the clusters in a database... you have to update that database a lot more often with small clusters. Another issue with small cluster sizes is the disk tends to get de-fragmented a lot more quickly. Large cluster sizes allow files to be written faster, however you loose storage space IF you have a lot of small files on the drive.

I changed my cluster size from 512 bytes to 64K (65336 bytes), and this very much improved my read speed. There are a few tools that you can change the cluster size of your drive without loosing data, but it is much less stressful to copy your data to a backup drive, format with the correct cluster size and then copy the data back.

Wow - this turned out to be a long post

jhhoffma · Post by **jhhoffma** » Wed Feb 25, 2009 12:32 pm

What codecs and software are you using to record/playback your video?

MPEG2 has been GPU accelerated for a long time now, so you should not have any problem viewing high res files, from a hardware standpoint anyway.

dvasco · Post by **dvasco** » Wed Feb 25, 2009 2:24 pm

Hey guys, thanks for the replies. I use PureVideo as an mpeg2 decoder. I also have Dscaler, ffdshow, and a few other things installed. I use Zoomplayer, WMP, GBPVR, and Totalmedia that comes with the Kworld USB tuner. GBPVR lets me choose which mux, audio, and video codec I want to use. I have problems no matter what I use.
I converted the drive to NTFS a year or two ago. I have really good reception for ATSC stations on the tuner and a standalone DTV tuner that connects directly to a standard TV.
I read a lot of negative reviews on Newegg about all of the USB tuners and I think they were in the same boat I am but didn't know about some of these forums or how to go about trblshooting, so they didn't find a solution, which I am determined to do. On the GBPVR forum it seems it is hit and miss on who can get their system working with ATSC.

jhhoffma · Post by **jhhoffma** » Wed Feb 25, 2009 5:40 pm

Well, for sure PC based tuners do not have the same sensitivity as TV-based tuners do. So it's possible that the signal isn't strong enough to be stutter free. Do you have any issues with Live TV? If not, then it's a playback issue.

Are you doing any other post-processing with ffdshow? Doing things out of order when PP with ffdshow will screw things up in a hurry. I would uninstall all codecs and packages except for ffdshow and dscaler. Make sure everything is turned off in ffdshow (resize, Blur & NR, postprocessing, sharpen, etc).

After that, I'd look at the drivers for your tuner.

teststrips · Post by **teststrips** » Thu Feb 26, 2009 9:31 am

Can you play the video outside of GBPVR in something like VLC (which should use its own codecs to pay the video).

I haven't played with GBPVR for over 2 years, but back then it had trouble recording ATSC streams. From what I remember the developer (Sub) lives in England which has DVB signals... he has no easy way to test ATSC, so it doesn't always get the attention that us here in the US would prefer. What I'm getting at here - does the software that came with your USB tuner provide any different results... if your tuner didn't come with software, try the trial for SageTV or BeyondTV