Hi,

I currently have a FE/BE combo, and I want to expand my setup with a dedicated backend and then several frontends throughout the house. The combo unit has a sempron 2800+ and GeForce Nvidia 6200 video card. I record digital ATSC only, so its a mix of SD and HD. Performance is pretty good unless I'm playing back an HD recording while mythcommflag is running.

So I'm looking at processors and mobo's and want to plan properly. The faster Athlon's look pretty cheap (under $40 on newegg) and I'm thinking to get one of those instead of another sempron. So, should the BE or FE get the stronger processor?

Thanks,

Steve

The FE is the major CPU user. It's doing all the hard work of decoding and displaying the MPEG-2 stream, and with HDTV this can be quite a workout.

BE processing is mostly just simple data shuffling with very little processing. The only time the BE needs processing muscle is when you're running an SDTV software encoder, or for doing commercial flagging or transcoding which are asynchronous post processing. Even then it doesn't need that much. What a BE does need is plenty of space and low latency disk access. Any modern harddisk with DMA support should work there.

To give you some perspective (These are all R5D1 + .20 systems):

Master backend: P4 2.4Ghz, MSI motherboard, 512mb RAM, MX440 video (no frontend), PVR-350, PVR-150, Fusion HDTV Lite, and like tjc said lots of storage. Sits in my basement, only notice it "huffing and puffing" when commflagging and recording at the same time. I manually transcode the recordings I want to keep (not often) and notice that consumes a lot of CPU.

Frontend #1: Athlon 64 X2 3800+, Asus M2NPV-VM, 1Gb RAM, onboard 6150 video (DVI -> DVI), 40Gb HD, no capture cards. Attached to Sony rear-projection HDTV-ready TV. Plays HDTV smoothly using Bob deint and Standard MPEG2 decoder, no problems.

Frontend #2: Athlon 64 3200+, Asus M2NPV-VM, 512Mb RAM, onboard 6150 video (Svideo), 120Gb HD, no capture cards. Attached to old 35" tube TV, no HDTV playback necessary (although this was Frontend #1 and worked fine)

Frontend #3: P4 3.06Ghz, ASRock P4i65G, 512Mb RAM, GeForce 6200LE 256Mb (DVI -> HDMI), 20Gb HD, no capture cards. Attached to Samsung LCD HDTV, playback smooth in the testing I have done so far (not quite in commission yet, next couple of weeks)

I was surprised to see you are getting good results with a Sempron 2800+. In my research the "baseline" HDTV rig seemed to be a P4 3Ghz or equivalent and 1Gb RAM. Are you using XvMC? Which version of KM are you running?

My KnoppMyth is version R5e50. Yes, I should have added that I'm using XvMC. That's part of what's driving my question I think, because what I've read indicated that XvMC shifts all the hard work to the graphics card. I'd really like to do more "archiving" type things like converting to Xvid, which seems (1) very processor intensive and (2) very backend oriented.

I've burned a few dvd's of stored recordings and really that's where I feel the "slowness" of the Sempron. I think the 2800 means its comparable to a 3ghz pentium. I also have 1gb RAM on a single module. BTW the Sempron is overclocked as well. I use HD component out to a 720p LCD Vizio TV.

I didn't find XvMC to be helpful in HDTV playback on my systems, there may be newer versions that I haven't tried that are better in that respect.

Ahh, the overclocking with the 1Gb RAM is probably the trick. I don't follow the AMD/Intel comparisons so I don't know what the numbers actually represent, and I haven't overclocked a processor since the Celeron 300mhz days...

Thanks for the information

I'm really not sure just how much the overclocking helps or doesn't. Before I had XvMC going, and my video was stuttering, I enabled it and it didn't fix the stuttering. I really don't even know if I'm doing it right, what i read didn't quite correspond to the BIOS options I had to choose from. But its been months now and everything seems to be going OK so i haven't turned it off.

I'm a solid AMD fan when it comes to Athlons, but if you look at the benchmarks the Intel processor wipes the floor with the AMD when it comes to video encoding/decoding tasks.

I opted for a 3GHz P4 HT processor in my KM box and its performance has been stellar. I have three HD receiver cards and I use software decoding for playback. I can commflag the streams in almost real-time while recording them. It is a solid performer.

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Until I purchased the Fusion Lite card I was using exclusively Intel, and I couldn't even tell you why!
Now I'm using a 50/50 mix of AMD and Intel, depending on what I need from the system. "Horses for Courses"...

My house is about 50/50 split right now with Intel and AMD. My mythtv box is AMD based since I got the motherboard I was using as a gift. So far so good running Recording multiple feeds and playing at the same time. All with folding@home running in the background.