minolta
10th February 2004, 23:57
About 6 months ago I purchased a MyHD HDTV card. For HD sources, it has been great, but I don't like how it handles my analog sources (cable tv).
With my old bt878, if I captured with a vertical height of 480, I would capture both fields (thus visible interlaced lines). However, the Micronas chip on the MyHD automatically deinterlaces analog sources. The deinterlaced picture is updated at 60FPS, and actually looks good full-screen (somewhere between a 'bob' and 'tomsmocomp'). When I capture the true-interlaced content (sports, mtv, etc) with the supplied MyHD software, the resulting 720x480 AVI is always deinterlaced and 30FPS. If I were only making DivX or XviDs, this might be okay, but I prefer to make interlaced MPEG2s when the original content is interlaced. All told, I still use my bt878 with analog sources (not happy with the quality...).
But, here is where it gets good... I've tried using other software for capturing (VirtualDub, AMCap, iuVCR), but all instantly crash/restart my computer. However, I constructed the DirectShow graph manually using GraphEdit and that seemed to work. Now, I can even capture at 60FPS (hardware deinterlace is still active). If I capture at 720x240 at 60FPS, you might suspect that each field is captured in each frame, but there is no visible 'bob' effects, so the picture is just being scaled down. So the only way to get it ready for MPEG2 is to capture at 720x480 (or less, say 480x480) at 60FPS, then write an AVISynth script to throw-away and weave together at 30FPS. When capturing at such a high rate, it is nearly impossible to apply any compression (with my 2GHz machine). Best I can do is just old YUY2 (1GB in 25 seconds, not good...).
So, I've coded with DirectShow before, and I'm going to create an optimized filter that does a 60p to 60i conversion and horizontal resize (to 240, 384, 480, 512, 640x480). Only then will live compression, such as MJPEG, be possible. So, I'm writing this to see if other MyHD owners would be interested in this filter (or am I just too anal). Let me know, and I'll be sure to post it somewhere.
With my old bt878, if I captured with a vertical height of 480, I would capture both fields (thus visible interlaced lines). However, the Micronas chip on the MyHD automatically deinterlaces analog sources. The deinterlaced picture is updated at 60FPS, and actually looks good full-screen (somewhere between a 'bob' and 'tomsmocomp'). When I capture the true-interlaced content (sports, mtv, etc) with the supplied MyHD software, the resulting 720x480 AVI is always deinterlaced and 30FPS. If I were only making DivX or XviDs, this might be okay, but I prefer to make interlaced MPEG2s when the original content is interlaced. All told, I still use my bt878 with analog sources (not happy with the quality...).
But, here is where it gets good... I've tried using other software for capturing (VirtualDub, AMCap, iuVCR), but all instantly crash/restart my computer. However, I constructed the DirectShow graph manually using GraphEdit and that seemed to work. Now, I can even capture at 60FPS (hardware deinterlace is still active). If I capture at 720x240 at 60FPS, you might suspect that each field is captured in each frame, but there is no visible 'bob' effects, so the picture is just being scaled down. So the only way to get it ready for MPEG2 is to capture at 720x480 (or less, say 480x480) at 60FPS, then write an AVISynth script to throw-away and weave together at 30FPS. When capturing at such a high rate, it is nearly impossible to apply any compression (with my 2GHz machine). Best I can do is just old YUY2 (1GB in 25 seconds, not good...).
So, I've coded with DirectShow before, and I'm going to create an optimized filter that does a 60p to 60i conversion and horizontal resize (to 240, 384, 480, 512, 640x480). Only then will live compression, such as MJPEG, be possible. So, I'm writing this to see if other MyHD owners would be interested in this filter (or am I just too anal). Let me know, and I'll be sure to post it somewhere.