The moment you do this, you lose the ability to de-interlace the raw video effectively, since the interlacing will no longer be a clean and predictable effect. It's best to compress raw video using the final/preferred codec at the first stage.
This is completely untrue on two levels.
1) If you're saving the MPEG Transport Stream, you're not doing any re-encoding. You're just copying the data
2) Even if you were re-encoding, you can easily preserve the interlacing - provided you have a codec that supports interlaced encoding, and you set the field order properly.
I'm a professional compressionist. You're misinformed.
Now, regarding the issue at hand.
There are basically two ways to go about capturing HD video off QAM (cable) / ATSC (over-the-air). Satellite really only works with option 2, unless you have a custom, hacked set-top box.
1) Capture the MPEG Transport Stream (which can be done with several software programs)
2) Capture the HD video output of a set-top box, by using an HD capable, component video capture card, like the Blackmagic Video Recorder (
http://www.blackmagic-design.c...oducts/videorecorder/), Blackmagic Intensity Pro (
http://www.blackmagic-design.com/products/intensity/), or Hauppage HD PVR. Forget about HDMI capture - your set-top box will have HDCP encryption, and any capture card out there will simply not allow you to capture it.
Method 1 is far superior when possible, as it allows you to capture the stream as-is, then process as you need to, and finally re-encode into a storage format with an excellent codec like x264, which can easily cut the size of an MPEG-2 source by half with no perceptible loss in quality - especially a typically crappy and over-compressed QAM or ATSC broadcast.
Method 2 works, but is subject to a few problems.
A) The easiest solutions have built-in hardware encoders, like the Hauppage and the Blackmagic Recorder. While these do encode H.264, they do so not nearly as well as x264 does. It's not a HUGE deal, as you can simply encode at a very high bitrate, then filter / deinterlace, and encode again with x264 without much loss - but it's still another compression phase.
B) The other solutions, like the Intensity Pro, don't have hardware encoding. So, you have a couple choices. You can capture to uncompressed video - which requires ~1.5gbps of sustained I/O, so think 3-5 SATA drives in RAID 0 to handle. This is a HUGE PITA, and I would never suggest it . You can alternatively capture to an acquisition / editing format like CineForm, which is completely awesome, but a tad bit expensive. MJPG is another good option. Keep in mind, capturing HD video isn't nearly as simple or bulletproof as capturing SD video with VirtualDub.
Since you're trying to do Satellite, you're probably best off getting one of the products with a hardware encoder, capturing at the maximum allowable bitrate, then filtering with AviSynth (get neuron2's DGAVCIndexNV application for very good real-time deinterlacing on your GPU), and encoding with x264.
Lots of choices. Lots of ins and outs. Lots of fun to mess with.
Keep in mind, 3-5fps for encoding 1080p content with x264 isn't half bad for a slowpoke Athlon X2. Get a Core 2 Quad or a Core i7 if you can afford it . Still, even with your CPU you can probably improve performance. Use CRF mode if you're not already - this will make you forget all about 2 pass encoding. What x264 settings are you using?
Forget about CUDA encoders. There's nothing out there that delivers quality even approaching x264.
Oh, and don't use VirtualDub to encode x264.... It's such an ugly hax, and has plenty of issues. If you want something that feels like VirtualDub, try AviDemux. Otherwise, use a modern encoding GUI like MeGUI - or Ripbot264 if you want something simple.
~MiSfit