HD or no HD

Going from interlaced SD sources (DVD or MPEG2 tapes) to interlaced HD sources (ATSC) is going from 39/19.5 (Yonah) or 33/18 (D 805) to 12/9 fps.

Yonah encode SD at 1.25 RT (2nd pass or single pass) and overall 2-pass SD source transcode on Yonah is 0.6xRT+1.25xRT~ 2xRT. D805 is marginally slower (more on the 1st pass due to slow FSB?). Cropping and scaling HD sources to 640x480 would make 1st pass 2xRT and 2nd pass 2.77xRT and thus 4.77RT overall, or 2.2 times slower on (2nd or single pass) and 2.4 times slower overall on 2-pass encodes. There is just too much data in 1080i@30 and 720i@60 regarless of that at the end I end up encoding 640x480.

Overclocking D 805 should increase performance 154%, thus on my 25fps converts of SD sources 2nd pass should be 27.72 or faster then RT and about RT without changes to FPS. Similar performance should be expected from Core 2 Duo. This wouldn’t help ATSC transcodes scaled to 640x480 for on either - 2nd pass would be about 13.5 fps or ~2xRT and overall 2pass encode would take ~3.18xRT. Core 2 Duo would make 1 pass encode of ATSC wrapped SD scaled to 640x480 about as fast as 2 pass SD sources. Only Quad Core 2 would get us in the same ballpark with ATSC wrapped SD at 640x480 as Yohan with SD sources.

The above is based on 12/9 fps for ATSC SD which I need to verify once again.

ATSC wrapped HD would be even worse. Scaling to 640x368 would get us into the same 12/9 fps (4.77xRT) ballpark. Going to true 720p HD (1280x720) would double that to 4.5 fps on the 2nd pass, so even on 1 pass encodes we are over 5xRT that Quad Core 2 would probably make 1-pass 720p encode 2xRT and well built system should do 2-pass in 3xRT.

1080p would take even longer. How much longer would be interesting to find out. Thus the tests are:

1. 2-pass 640x480 ATSC on a) D 805 to prove 12/9 fps; b) Lenovo to see if it better – Those tests should take 4.77xRT, thus 1.5 hrs on shows. Go for 500kbps with those.
2. 2-pass 1000kbps 720p HD test to see how slow is the 1st pass. Looking at 9/5 fps or ~ 8xRT or 6 hours for 45 minute show.
3. Overclocking D 805 to see how far it would be from 13.5 fps on the 2nd pass/1-pass transcodes of ATSC wrapped SD. This test could be done on either mencoder (1-pass) with adjustment for frame-rates and would take 2xRT or 40 minutes; or with x264 to test if 1-pass would get better, but would take 3xRT or 1 hour.
4. Vista x64 test.
5. If I don’t have it already do 1080p HD 2-pass transcode

Thus I need 3 SD shows and 2 HD show and the fastest way is to cut commercials into drv-ms and use cut drv-ms. Lenovo would need about 3-5GB to do the test. For the sake of argument, put T2300 (478) into D600 and see if it would POST and start cooking that BIOS.

Overall, 5-8xRT 720p HD would need yet another generation of processors and definitely would need Quad to transcode 45 minutes shows in 1-2 hours vs. 6 hours it takes today.