pcHDTV :: View topic - My experiences with pchdtv3000 versus air2pc hd500

john.anthony.brown

My combined frontend-backend rig consists of the following:

1) AMD athlon xp 2800 (1.83 GHz)
2) 2 Gigs of DDR 333 MHz ram
3) PVR 150, air2pc hd500 tuner
4) geforce 5200 graphics with 128 mb onboard memory
5) 160 GB ata 133 hard drive for /var/video partition

I found the pchdtv card (previously installed) generally produced crappy quality recordings that often would crash my frontend.

I suspected the problem was the pchdtv's idiotic approach of dumping the entire transport stream to the system bus - so I set out to get an air2pc card that does hardware PID filtering.

The results after one week are breathtaking. The air2pc hd5000 card has produced flawless recordings every time. The rig no longer needs XVMC to play back the streams - and system load is way down. I can now watch one HD recording while it is recording another one. 1080i recordings are smooth as butter using libmpeg2 and kernel deinterlace.

The pchdtv 3000 would never let me do that on my rig.

So - Jack Kehler - PLEASE PUT HARDWARE PID FILTERING in your HD tuners. For me it has made all the difference.

I very much want to support your products and efforts - but this is a no brainer.

xyzzy

I doubt the hardware pid filter has anything to do with it. The software filter uses very little CPU time, next to nothing compared to what mpeg decoding takes.

Sending all the data across the PCI bus is really no big deal either. A HD channel takes up about 90%+ of the bandwidth of an 8-VSB OTA channel, and around 50% of the bandwidth of a QAM-256 cable channel. So even with a hardware pid filter you're sitll sending, half to nearly all of the packets are still going across the bus.

The datarate isn't even very high anyway. 8-VSB is about 2.5 MB/sec. Your hard disk is proably 10 to 20 times faster than that, and it works ok.

The difference your seeing is probably do to problems with noise. The HD-3000 has an older demodulator, while the air2pc hd5000 has a newer one (the same demodulator and tuner as the pchdtv HD-5500 in fact).