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ronnylov · 2nd October 2002, 01:19

I decided to do my own test instead of just talking.
This was the only way to convince myself.

I used two test pictures and created two DV Avi's in Ulead Mediastudio Pro 6.5 using mainconcept dv codec and canopus dv codec.

I noticed that the DV codec caused some compression artifacts on the "torture circle pattern" that I found in the avisynth forum discussing lanczos rezise. So I have attached original images and also the DVAvi encoded images.

I recorded the DV-Avis via firewire to my Panasonic NVDS-28 MiniDV camcorder in PAL 720x576 25fps format.

Then I connected the S-VIDEO out from the camcorder and captured it with my ATI All-In-Wonder Radeon using AVI_IO capture program and capturing to huffyuv avi 704x576 resolution.

Then I connected the camcorder to my SVHS VCR, JVC HR-S7700 and recorded to a new SVHS tape of good quality. I also recorded to an average quality normal VHS tape, both in SVHS ET mode (JVC has a method of recording to normal VHS with "almost SVHS quality"). I also recorded to the same tape in normal VHS mode, all recordings was done in "short play".

I captured with 704x576 resolution in huffyuv from all the VCR tape recordings with my VCR connected via S-VIDEO cable to the AIW Radeon.

Then I also did some tests by downsizing to a lower resolution and upsizing again from the lower resolution to 704x576 to be able to compare with the original images. I used the lanczos rezise both for down and upsizing in avisynth. The images was taken from copying source video to clipboard and then inert the picture in mspaint and then they was saved as bmp and afterwards converted to jpg to reduce the file size a bit.

CONCLUSION
VHS, SVHS and SVHS ET all have full vertical resolution compared to the original! The vertical resolution was the same in all formats. That makes the statement "VHS is 240 pixels vertical resolution" completely false!

The horisontal resolution seems to be close to 352 pixels in VHS mode. It can be seen in the "circle torture clip" that the resolution does not increase above 480 pixels horisontal resolution. There is a small difference between 352 and 480 pixels resolution but it seems closer to 352 than 480 in my eyes. 320 pixels was a little bit worse and 240 pixels was too low. In SVHS the resolution is almost the double compared to VHS. SVHSET is not recommended unless the tape is of very good quality because it introuduced a lot of noise. VHS looked better on this tape.

In my case I'm converting to DVD and to me it seems that 352x576 is the most resonable format to use when copying VHS to DVD, but if it is a recording of high personal value I may use 704x576 rsolution. Remember that I'm looking at uncompressed images and it may be very likely that video compression to MPEG-2 or any other format makes the image a little bit more blurry so to compensate for that it may be nesessary to go higher than 352 horisontal resolution. But don't downsize vertically because now it has been proven that you need the full vertical resolution! I did one test with downsizing to 544 pixels heigth and it was a visible decreased resolution in the output!

Images

2nd October 2002, 01:19	#25 \| Link
ronnylov Registered User Join Date: Feb 2002 Location: Borås, Sweden Posts: 492	My test results I decided to do my own test instead of just talking. This was the only way to convince myself. I used two test pictures and created two DV Avi's in Ulead Mediastudio Pro 6.5 using mainconcept dv codec and canopus dv codec. I noticed that the DV codec caused some compression artifacts on the "torture circle pattern" that I found in the avisynth forum discussing lanczos rezise. So I have attached original images and also the DVAvi encoded images. I recorded the DV-Avis via firewire to my Panasonic NVDS-28 MiniDV camcorder in PAL 720x576 25fps format. Then I connected the S-VIDEO out from the camcorder and captured it with my ATI All-In-Wonder Radeon using AVI_IO capture program and capturing to huffyuv avi 704x576 resolution. Then I connected the camcorder to my SVHS VCR, JVC HR-S7700 and recorded to a new SVHS tape of good quality. I also recorded to an average quality normal VHS tape, both in SVHS ET mode (JVC has a method of recording to normal VHS with "almost SVHS quality"). I also recorded to the same tape in normal VHS mode, all recordings was done in "short play". I captured with 704x576 resolution in huffyuv from all the VCR tape recordings with my VCR connected via S-VIDEO cable to the AIW Radeon. Then I also did some tests by downsizing to a lower resolution and upsizing again from the lower resolution to 704x576 to be able to compare with the original images. I used the lanczos rezise both for down and upsizing in avisynth. The images was taken from copying source video to clipboard and then inert the picture in mspaint and then they was saved as bmp and afterwards converted to jpg to reduce the file size a bit. CONCLUSION VHS, SVHS and SVHS ET all have full vertical resolution compared to the original! The vertical resolution was the same in all formats. That makes the statement "VHS is 240 pixels vertical resolution" completely false! The horisontal resolution seems to be close to 352 pixels in VHS mode. It can be seen in the "circle torture clip" that the resolution does not increase above 480 pixels horisontal resolution. There is a small difference between 352 and 480 pixels resolution but it seems closer to 352 than 480 in my eyes. 320 pixels was a little bit worse and 240 pixels was too low. In SVHS the resolution is almost the double compared to VHS. SVHSET is not recommended unless the tape is of very good quality because it introuduced a lot of noise. VHS looked better on this tape. In my case I'm converting to DVD and to me it seems that 352x576 is the most resonable format to use when copying VHS to DVD, but if it is a recording of high personal value I may use 704x576 rsolution. Remember that I'm looking at uncompressed images and it may be very likely that video compression to MPEG-2 or any other format makes the image a little bit more blurry so to compensate for that it may be nesessary to go higher than 352 horisontal resolution. But don't downsize vertically because now it has been proven that you need the full vertical resolution! I did one test with downsizing to 544 pixels heigth and it was a visible decreased resolution in the output! Images __________________ Ronny Last edited by ronnylov; 2nd October 2002 at 08:04.