DV is compressed, so can I get better video by capturing … raw?

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DV is compressed, so can I get better video by capturing … raw?

Posted by Jill Simpson on February 4, 2009 at 1:01 am

I recorded on SD DV. I captured using the “Windows Import Video” program with a “RICOH OHCI Compliant IEEE 1394 Host Controller” device. The avi files are ~13 GB per hour of video.

(On my monitor and SD TV, the videos look great – I’m not reporting a problem; I’m just checking. On the chance my work gets accepted in a film festival, I’d like it to look as good as possible on a movie screen.)

Thanks.
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– 4 GB RAM
– Intel duo core processor, 2.16 gHz EACH, 4.3 gHz total
– Vista 64-bit (32-bit able), with SP1
– Video Card: NVIDIA GeForce 8400M GS
– Sound Card: RealTek High Definition Audio, 6.0.1.5384
– Camera: Sony DSR-PD170. Also: Kodak m1033 digital.
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Jilligan

Jill Simpson replied 17 years, 3 months ago 2 Members · 2 Replies
2 Replies

John Rofrano
February 4, 2009 at 1:15 am

The DV signal is already compressed on the tape. There is nothing you can do to get better quality. Firewire isn’t like analog capture. You really aren’t “capturing”. You are simply copying the file bit-for-bit as it appears on the tape. It is more like a file transfer and it is 100% lossless. What is in the DV AVI file is exactly what’s on the tape.

~jr

http://www.johnrofrano.com
http://www.vasst.com
Jill Simpson
February 4, 2009 at 8:38 am

Thank you. After your reply, I found a webpage that had some info which bears repeating, lest anyone else reads this thread. A modified extract is below. (Source: http://www.infocellar.com/Video/dv.htm)

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Uncompressed full-screen Video – 31 MBps
Uncompressed Audio and Control data – 0.5 MBps

Calculations:
NTSC DV Video is 720×480 using 3 bytes for color info (3 bytes per pixel)
720x480x3 = 1,036,800 bytes/frame
29.97 frames/sec x 1,036,800 bytes/frame = 31,072,896 bytes/sec (31 MBps)

Compressed DV (using DV25 codec)
– Camera Compression of video – 10:1, stored on tape at 3.1 MBps
– Camera compression of audio and control info – None – stored on tape at 0.5 MBps
– Camera Compression overall 8.6:1.

Total Data Rate = 3.1 + 0.5 = 3.6 MBps

During filming compression occurs in the camera (not the capture)!! The data stored on the miniDV tape is compressed.

During capture, no compression occurs – the data is just piped into the computer, as is, and stored on the hard drive at 3.6 MBps.

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