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Brad Williams
compression
on Aug 18, 2010 at 1:18:07 am

I have a question. For our church we use a lock down camera to record video for a video venue. It is a JVC GY-100HD. It records at 720P30. I am recording to a FS-4 Pro HD and then dump it into Final Cut using the same codec to cut the front off and fade the back to take to venue. I then export the video file using HDV 720P 30 preset to a video file.Will this process deliver the best quality video file that I can ? We are looking at changing to a Sony EX-3 for this camera and I believe will get a better picture. Venue says video looks fuzzy and not crisp or clear enough.


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Chris Blair
Re: compression
on Aug 18, 2010 at 3:26:14 am

We'd need a lot more info to help at all on this. Read the sticky note at the top of the forum titled:

How to get FASTEST compression help - PLEASE READ

But I will say that compressing to HDV is NOT going to give you great quality. HDV is barely even a professional format. A lot of broadcasters either won't accept it or the content has to only include a small percentage of HDV sourced material.

It's typically MPEG2, 4:2:0 (half the color is thrown out) and the data rate is roughly 20mbits/sec...(that's 2 Megabytes per second).

For comparison sake, according to Blackmagic Design's website, uncompressed 8-bit 720P HD = 105 MB per/sec. So your exported footage is compressed at a whopping 52:1 and half the color is thrown out.

So I would think encoding to something more robust that doesn't get rid of half your color and compress as heavily would be better choice.

Why not just use the native codec and avoid re-encoding? I believe the JVC camera you mention records to Sony XDCAM, which is double the data rate and I believe it's 4:2:2. That's why we need more info...like...what is the venue using for playback?(I'm assumig you're talking about a remote location where the video is played??)

Also...depending on your shooting conditions, expectations may be higher than they should be. If you're shooting in low or very contrasty light (with no articifical lighting added), then you're going to have a tough time getting high quality images.

Give us more info and answer some of these questions and people can likely help you out.

Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com
Read our blog http://www.videomi.com/blog


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Brad Williams
Re: compression
on Aug 18, 2010 at 11:27:14 am

k, sorry, I am using a Quad Core Mac Pro to import the raw footage from the FS-4 Pro HD into Final Cut 7. I am running Snow Leopard with 6 gb of ram. I drag the footage straight into the timeline and then export back out using Quick time movie to the same HDV 720 P 30. The venue plays the file straight from Final Cut using a brand new iMac that goes through a Kramer scaler to a Sanyo HD projector.The JVC only shoots 720p. I have a Sony deck, not sure which model I have. I am going to shoot footage today with the Sony EX-3 to see if I can achieve better results. For our broadcast we shoot with a Panasonic HPX 300 straight into the Mac Pro through a Blackmagic Deckling Extreme at 1080i which obviously is a better quality picture. I can't use this for video venue becuase the video venue uses a lock down shot which is from floor to1 ft above the pastors head. Maybe this will provide more insight. The venue complains because they can take a commercial DVD and see a better quality picture.


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Chris Blair
Re: compression
on Aug 19, 2010 at 12:49:48 am

Hmmm...interesting. Scaling 720P to 1080i should not result in a huge loss...there have been lots of engineering studies that have shown 720P and 1080i are very similar in terms of overall resolution. Now 1080P would show it, but 1080i should not.

If they have Final Cut on the laptop...I don't understand why you export to HDV? Why not just export using the native XDCAM that came out of the JVC camcorder?? Or..is the FS-4 recompessing the signal out of the JVC camcorder to HDV? That would be the first thing I'd investigate...keep your signal in HDCAM since it's 4:2:2 color space and it has a data rate of 35mb/sec. HDV is 4:2:0 and runs at 19mb/sec, so it's way more compressed than the Sony XDCAM.

Next place I would look would be the settings coming out of Final Cut on the laptop...are they correct...meaning field order set properly, pixel resolution match your exported file, frame rate match etc.

Then I would check the scaling from the Kramer unit. We own some Kramer products and most are very good, but if you have even one incorrect setting, it can cause blurry, jittery video.

Last....is the Sanyo projector a true HD projector? It would need to project either 1280x720 or 1920x1080 to be true HD. Also, is the feed from the Kramer getting scaled yet again to whatever the size the projector is sending or does it match the projector.

Whew...you got a lot of cogs in your wheel...I'd check all those before switching camaras...I can't imagine the Sony EX3 is going to be that much better than the JVC model you're using.

Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com
Read our blog http://www.videomi.com/blog


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Brad Williams
Re: compression
on Aug 19, 2010 at 1:06:05 am

Chris,

yes a lot to process. 1st, the difference between the cameras was significant. I am capturing tonight from the Sony EX-3 to the FS 4 . It will not be in HDV now so I can see the difference. The settings are the same in the iMac at the venue. The problem was that there was a corrupt file in the Final Cut preferences. So I trashed preferences and did a disk repair and all is well with that now. Another thing that I found was that yes the Kramer was scaling to the 1280x720 and the installer used a VGA scaler to the projector instead of running DVI to the projector, so it is, out of the iMac, to the Kramer, out VGA to the HD projector. I have to change that as well.


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Chris Blair
Re: compression
on Aug 19, 2010 at 3:45:15 am

Sounds like you're making progress. Keep us posted on how it turns out.

Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com
Read our blog http://www.videomi.com/blog


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Brad Williams
Re: compression
on Aug 18, 2010 at 12:55:28 pm

k, sorry, I am using a Quad Core Mac Pro to import the raw footage from the FS-4 Pro HD into Final Cut 7. I am running Snow Leopard with 6 gb of ram. I drag the footage straight into the timeline and then export back out using Quick time movie to the same HDV 720 P 30. The venue plays the file straight from Final Cut using a brand new iMac that goes through a Kramer scaler to a Sanyo HD projector.The JVC only shoots 720p. I have a Sony deck, not sure which model I have. The model is the hvr-15MU which is the HDV cam. We previously shot SD and then dumped to tape here for our venues.


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