Decoder Quality / TIVO envy

[salsbst]

If you can get PowerDVD to work then you may find it to be the best at decoding the 250s files.

[jptaz]

I liked PowerDVD but sadly my system was too slow for it to work. It looked great but the computer could not keep up so it slowed to a halt and was unresponsive.

I believe that the reason I did not have as much issue with say "Alias" or movies is that they were originally progressive as they are HD which is down converted as JMbouk noted the interlacing will be better.

John

[billeR]

I have a question about the value of hardware encoding vs. decoding that the discussion above has prompted. Aren't most of our PQ problems really more a function of the encoder (whether hard or soft)? Here's my thinking - please correct as necessary:

I have spent the proverbial "50 hours" tweaking my setup to try and squeeze the best PQ out of my system as possible. I encode using a pvr250 & run the DVI out of my Radeon 9600 w/powerstrip to get dot-for-dot on my 43" Pioneer plasma. I have determined that my best PQ (so far!) comes from using a dedicated media partition w/64mb blocks, a custom quality setting of 8mb/s in the properties file, the elecard software decoder and the dscaler plugin videoweave with dbl frame rate (make sure to turn off software deinterlacing in the elecard registry) and after spending mucho timo tweaking brightness/contrast/hue/saturation/sharpness trying to get them just right.

However, despite my best efforts, my PQ of "liveTV" is immediately and obviously inferior to the PQ I get when I go directly to my pio from the D* stb. I still see stuttering and motion artifacts, especially on high motion video like sports. Now, I know that I can use the exact same software decoder and play other high bitrate mpeg files like DVD's that don't have any of these artifacts and PQ issues. In fact they are better than my direct from stb NTSC PQ (of course). Isn't the difference between the PQ of a dvd mpeg file played back using the exact same software decoder the quality of the ENCODING. I mean a dvd is encoded frame-by-frame on dedicated hardware that costs a bizillion dollars at an uber-studio. On the other hand, my pvr250 is a good consumer level hardware encoder, but it just can't keep up with the demands of encoding at a bitrate high enough to prevent macroblocking and other artifacts. Not to mention that our poor pvr250's are already fighting with one arm tied behind their backs because they are really re-encoding a mpeg stream that has already been decoded once by my stb. Isn't the benefit of a hardware decoder mostly cpu capacity related, but kind of irrelevant if are decoding mpeg files that have flaws introduced by the encoder?

I recently bought and love the Sage software after demoing Sage & SS, and found it to be far superior in terms of PQ (UI is another story - can't wait for v2). Basically, all I really want is for my PVR encoded material to look at least as good as what I can get if I just skip the PC and go straight from my stb to my display. Unfortunately, I have the sneaky suspicion that since my display is fixed pixel, and fairly large, I am screwed. By that I mean that it is critical that I get good deinterlacing (not the case for most "regular" tv's), that I get good scaling (native rate/res for my fixed pixel display), and that many flaws that are hidden by a 30" crt with 5% overscan and an interlaced display are made painfully obvious on my 43" computer monitor.

On the positive side, DVD's look far better when played back (using a software decoder) on my htpc than they do from my stand-alone progressive scan dvd player, but that doesn't have anything to do with SageTV. (I use the theaterrtek player w/ffdshow & dscaler)

Can anyone can help me get on the path of enlightenment. Is there anything else I can do, or am I limited by what is coming into my pvr250 and what it's encoding limitations may be?

[mlbdude]

DVD's are encoded using multi-pass. This allows the encoder to first go through the video and see what bits are required for each frame to get the best PQ. Then, on the next pass the actual video is generated. There is no way to do this in real time so this is not an option for the 250. One trick I have found is to use a custom quality encoding with a high bitrate setting and using CBR and NOT VBR. It seems with VBR the encoder try to use a little bits as possible then adjusts as fast as it can when needed. Problem is fast enough is never fast enough for me.

[billeR]

As noted above, I have created a custom quality setting at 8mb/s. I didn't mention it, but it is CBR. (VBR=0). It's the most recent tweak I've made, and improved the PQ, but I still have motion issues. I really think it's just a combination of the limitation of the pvr250 encoder and the fact that it's re-encoding a previosly decoded mpeg stream from my stb.

[mikejaner]

Yeah, if you have DirectTv or Dish Network, of course you can't get any better than the source. Artifacts in the picture on the channel your watching are going to be in the Sage recording your making. What you don't want is for the artifacts to get bigger or worse looking due to lower resolution capturing than the source, or bitrates lower than the source.

As for DVD refrences, we have take into account two things which will never stand up to DVD quality.
One, the source they use to encode a DVD is almost limitless in resolution and is uncompressed.
Two, the resolution of a DVD is higher than any standard broacast will ever be. I am not accounting for HD cause that is an whole other ball of wax.

All in all I am pretty happy with the quality of the capture portion of the PVR cards, and I am anxiously awaiting for the playback to be fully functional for my 350.
My Tivo and the 350 are really close with the 350 on the top. Close enough that after five minutes, I don't even remember what source I am watching and have to check the tv inputs.

mikejaner

[OPTIMO]

Originally posted by mikejaner
The PVR 350 has a decoder chip which is designed for the same purpose as the Tivo, therefore, has excellent quality. I purchased a PVR 350 about two months ago, and have never looked back. SageTV 2.0 will have full support for this card, including the interface and overlay. This card, I can tell you has better output quality than my Tivo, although it's close. Look into this card, but understand it's limitations like, no DVD and Windows output.

mikejaner [/B]

It was this review that made me recently purchase the PVR-350. After screwing around with KnoppMyth with minimal success I pulled out my WinXP CD, tried WinTV, GBPVR and then SageTV.

I'm anxiously awaiting 2.0 as it has many added features for the 350.

I'm recording at 1.5gb/hour and my shows look good running through S-Video and my flatscreen 32" Trinitron. The audio is running through my Audigy and into my 5.1 Home Theater setup with AperionAudio speakers.

The only drawback to the PVR350 is the inability to play DIVX and other AVIs through the output.

What's the cheapest but still nice output solution to this problem?