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(MPG4) Sanyo Xacti (all models)
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Old November 21st, 2006, 10:44 AM   #1
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Slow Motion

I am interested in seeing slow motion shots of tennis swings.

I am thinking the HD1 may be the only reasonably priced camera out there that can handle higher than 30fps, correct? I am also considering the older JVC GR-HD1 and Sony with "Smooth Slow Motion" for three second slots.

I have some questions.

1. For the HD1, can I play back the video on the LCD in slow motion, even looking at frame to frame?

2. Do I need the docking station in order to connect via component cable?

3. I am a little confused of what the 60fps will look like. It is, I believe, 640x480. Is that DVD quality? or when the JVC GR-HD1 can do 480P at 60fps, is that a better quality? I am not sure how the pixel count of 480 and line count of 480 compare, and does the 60fps mean progressive or is that totally unrelated because one is a measure of capture and the other a playback. Does the HD1 put out progressive at 640x480 at 60fps, and therefore does it need to go across the component outputs?

4. It seems from reading about the Sony "Smooth Slow Motion" that it is still capturing at 30pfs and recording it to the tape or dvd at 240 fps, but maybe it really is capturing faster at a lower resolution, similar to what the HD1 does but at a much lower resolution and much faster fps. This is what the clips look like that I have seen. I am wondering if running in slow motion or frame by frame if the HD1 would look better than Sony "Smooth Slow Motion".
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Old November 21st, 2006, 12:09 PM   #2
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I'm not sure but check this out

http://www.youtube.com/watch?v=MX6aerxQPOs

slow motion is incredible
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Old November 21st, 2006, 02:21 PM   #3
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That is great. Now if the HD1 could do that, I would really be amazed, ha ha!
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Old November 21st, 2006, 04:53 PM   #4
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My understanding of the Sony slow motion capture is it records at the higher frame rate (and reduced resolution) into a buffer, and then saves the images at 30 fps.

If all you want is a 50% slowdown, you can also try using a bob deinterlace from a 60i signal. The final resolution, even without any fancy deinterlacing algorithms, will have a similar vertical resolution and greater horizontal resolution, and you're not constrained to short clips. Sony's slow motion capture should be better at higher frame rates, although some software packages (e.g. Twixtor) allow pretty impressive slow motion from a 60i signal.

This is all post-processing, though, so you can't use it for feedback at a tennis lesson.
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Old November 21st, 2006, 06:55 PM   #5
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I see it was already answered in this group that you can do slow motion on the HD1.

http://dvinfo.net/conf/showthread.php?t=64379

I am not sure what the difference is between playing something in slow motion versus all the post processing described. I would guess the post processing would allow slow motion to be slow in normal play mode versus needing to slow something down in playback.

Also, from SteveDigiCam reviews it appears the component cables can go right into the HD1 without the dock, so I believe that is answered as well.

I am just wondering which will look better in reviewing tennis swings, Sony "Smooth slow motion" or HD1 with 60fps in slow playback mode. I may just need to try both to find out.
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Old November 22nd, 2006, 06:17 PM   #6
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I haven't paid much attention to how cameras or DVD players generate slow motion, but I suspect most cameras/DVD players just stutter frames to reduce the frame rate (that is, generate a full frame through some form of on-the-fly deinterlacing, and show it for 2x/4x/8x as long to generate a 50%/25%/12.5% frame rate). Free/low-end video editing software (e.g. iMovie) typically does the same thing. The net effect is jerky video -- its tolerable for some purposes but noticable.

Better (and slower) deinterlacing techniques that use both fields yield a smoother result at 50% frame rate. Software like Twixtor goes another step and actually extrapolates what the intermediate frames should look like. It all depends on your purpose -- using the slow motion feature on your camera/DVD player remote is probably good enough to analyze a tennis swing.

-Terence
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Old November 29th, 2006, 04:22 PM   #7
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Got my camera today, argh, Steve's digicam review isn't correct or I misunderstood it.

at http://www.steves-digicams.com/2006_...s/hd1_pg2.html

he says: "The Component Audio-Video cable plugs directly into the docking port and allows connection to HDTV displays with separate RGB video and L-R stereo audio."

this is right below a picture where he shows the component cables with the end right next to the camera. However, the cables cannot connect to this docking port! They need to connect to the docking cradle, which I do not have. So I will be looking at other ways to show the videos. I was thinking of primarily using the videos on a computer anyway.
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