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NTSC Aspect Ratio

 
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Joined: 02 May 2004
Posts: 45

PostPosted: Sun 2 May 2004, 15:42    Post subject: NTSC Aspect Ratio Reply with quote

I used the firewire port off of my Sony TRV-820 (Digital Cool camcorder to capture some video to DV-AVI format.

I load up TMPGEnc and select the avi for processing. It defaults the aspect ratio to "4:3 525 line (NTSC, 704x480)." Is this correct? I assume the program knows what it is doing and has changed the aspect ratio from the usual NTSC 720x480 for a reason? I believe it is because DV format outputs in CCIR 601, correct?

Thanks for any guidance on this matter!
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Joined: 02 May 2004
Posts: 45

PostPosted: Sun 2 May 2004, 16:31    Post subject: Reply with quote

Ok, I think I found the answer I was looking for:

http://dvd-hq.info/forum/viewtopic.php?t=23

What I did was use my camcorder as a "pass-through" for an analog source. As in, I plugged my laserdisc player into the camcorder, then firewired out to my computer. It sounds like, in the post above, that regardless of this the digital camcorder captures and exports full 720x480.

Please let me know if I am wrong Smile
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RMN
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Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Tue 4 May 2004, 0:00    Post subject: Reply with quote

Your file is definitely 720x480, because that's the NTSC DV resolution. Now, what the camera did when you imported from analog is anyone's guess. Even at the risk of getting a (very sightly) wrong final aspect ratio, I would suggest telling TMPGEnc not to resize the image (ex., set both source and output to "4:3 Display" and set the video arrange method to "Center"), since any resizing causes some loss of quality.

RMN
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Joined: 02 May 2004
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PostPosted: Thu 20 May 2004, 22:37    Post subject: Reply with quote

rmn wrote:
Even at the risk of getting a (very sightly) wrong final aspect ratio, I would suggest telling TMPGEnc not to resize the image (ex., set both source and output to "4:3 Display" and set the video arrange method to "Center"), since any resizing causes some loss of quality.


Why would this trigger a wrong final aspect ratio since the input and output sizes (720x480) are the same? Does it have to do with that "actually 4.02:3, not 4:3" thing?
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RMN
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Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Fri 21 May 2004, 3:00    Post subject: Reply with quote

When your camera converted from analog to DV, it may have changed the original frames' aspect ratio slightly (it's the 704-vs.-720 or total-pixels-vs.-visible-pixels thing). Theoretically, you could now correct that, when converting from DV to MPEG, but resizing the image will cause a loss of quality, so it's probably best to keep it as it is, even if a slight error was introduced during the A->D conversion.

RMN
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