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| pathfinder |
| Posted: Oct 28 2002, 08:54 AM |
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Unregistered
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Hi
I wonder which way do we loose more detail: capturing both fields (broadcast TV or DV PAL 720X576) of a 90 minute video and compressing it into 700 MB by DivX or capturing one field (???X288) and compressing it into 700 MB by DivX?
By the way, does anyone know if VHS stores the full scan line or half of it (quarter frame)? |
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| BaronVlad |
| Posted: Oct 28 2002, 09:09 AM |
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Terrorhörnchen
Group: Moderators
Posts: 335
Member No.: 28
Joined: 12-July 02
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always capture both fields if you want the best possible quality and your system is fast enough
The vhs thing is described in the Doom9 Capture FAQ:
| QUOTE | 10.) Why is a high resolution recommended when capturing VHS.?
- We all know that VHS VCR has a resolution of 320x240?
A: First, VHS has no "resolution" of 320x240. This is just an old rumor. Second, if you use filters, there is a big difference in using a low resolution (less informations for the filter) and full PAL (or NTSC) resolution. Last but not least it all depends on your taste, if you are satisfied with a 352x288 direct Divx ;-) capture, then by all means use such a low resolution. In the end only you can tell if the quality is satisfactory.
A very good thread that explains in theory why all those '320x240 stories' are just incorrect:http://forum.doom9.org/showthread.php?s=&threadid=34122 |
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Hochachtungsvoll
BaronVlad
Deutsch >> Capture FAQ - Capture Guide
Englisch >> Capture FAQ - Capture Guide |
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| pathfinder |
| Posted: Oct 28 2002, 10:50 AM |
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Thanks BaronVlad
I understand that both fields will give more detailes in the captured file (before compression). However DivX has to sacrifice some detailes to squeeze the file into 700 Mb, doesn't? So, the question (in fact a bit theoretical) is wheather squeezing a 4 times (compared to 352X288) or 2 times bigger (compared to 720X288) stream only by means of DivX will lead to higher loss of detailes than loosing some detailes during one field or quareter field capture and some inside the DivX codec (judged against the original picture in the source carrier (say DV tape)). Especially in regards to small detailes (like video noise). |
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| BaronVlad |
| Posted: Oct 28 2002, 11:28 AM |
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Terrorhörnchen
Group: Moderators
Posts: 335
Member No.: 28
Joined: 12-July 02
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You should save as much informations as possible during capturing, cause filters only can do a good work, when they have enough informations to work with. Therefor use full PAL (or NTSC). After capturing you should do a resize (I use 7xx*576 resized to 512*384 normally bicubic resize (-0.75)).
You can compare it to a picture: If you have a high resolution picture and zoom out, it becomes (visually) better, if you zoom into a small picture it seems to be low quality.
You will have less noise effects visually in the final movie. That is my (not only  ) experience.
1/4 PAL (384*288) is possible, but I am afraid it is only the fast way, it is not your choice for highest quality.
I hope, you got, what i wanted to say
 Sorry for my crappy English
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Hochachtungsvoll
BaronVlad
Deutsch >> Capture FAQ - Capture Guide
Englisch >> Capture FAQ - Capture Guide |
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| pathfinder |
| Posted: Oct 29 2002, 03:14 AM |
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Unregistered
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Thanks Vlad for good explanation |
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