Vhs capture advice.

[Alwyn]

"Required"? Why so?

Tried this in VDub, no joy, it just spits out "BT470". Any suggestions?


[Attachment 69346 - Click to enlarge]

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4.1
Format settings : CABAC / 5 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 5 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 5 s 680 ms
Bit rate : 22.8 Mb/s
Width : 1 440 pixels
Height : 1 080 pixels
Display aspect ratio : 4:3
Frame rate mode : Constant
Frame rate : 25.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.587
Stream size : 15.4 MiB (99%)
Writing library : x264 core 157 r2935M 545de2f
Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x1:0x131 / me=umh / subme=9 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=2 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=crf / mbtree=1 / crf=15.9 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Color range : Limited
Matrix coefficients : BT.470 System B/G
Codec configuration box : avcC

[Sharc]

Original post deleted.

Edit: SAR (Sampling Aspect Ratio) aka PAR (Pixel Aspect Ratio) is 16/15 (PAL 4:3 mpeg2) in this case. Probably not an analog VHS tape capture, but a 'native digital production' similar to a DVD. So yes, when playing the full frame as 4:3 the circle is undistorted.

[Alwyn]

My main motivation in posting that circle was to allow experimentation with cropping. For example, if one simply crops two lots of 8 pixels away to give 704x576, you end up with a distorted image at 4:3.

[Sharc]

My main motivation in posting that circle was to allow experimentation with cropping. For example, if one simply crops two lots of 8 pixels away to give 704x576, you end up with a distorted image at 4:3.

Agree. Because this source is not from an analog tape transfer.

[Alwyn]

Because this source is not from an analog tape transfer.

Yes it is; as I stated, it is a capture from a VCR recording of a TV program.

[lollo]

"Required"? Why so?

read and study https://forum.videohelp.com/threads/405794-VHS-PAL-cutting-and-upscaling/page2

Tried this in VDub, no joy, it just spits out "BT470". Any suggestions?

No idea, sorry. I do not use VirtualDub or any other useless GUI for cropping/addborders/resizing/change matrix, just AviSynth, where you have full control. Maybe Sharc can help here...

[dellsam34]

Last time we discssued about that you were not aware of it https://forum.videohelp.com/threads/405794-VHS-PAL-cutting-and-upscaling/page2

I thought it was nice to remind it

Did you read post #34? You must have glossed over it. I didn't point it out here because assumed the software the OP uses will automatically adjust when an HD resolution is shosen.

[dellsam34]

My main motivation in posting that circle was to allow experimentation with cropping. For example, if one simply crops two lots of 8 pixels away to give 704x576, you end up with a distorted image at 4:3.

Be careful with images generated by digital graphics machines back in the day such as Quantel machines, They don't have nor conform to a proper aspect ratio, The frame is usually smaller and padded with black borders, producers tend to stretch the image to fill the screen.

[lollo]

Last time we discssued about that you were not aware of it https://forum.videohelp.com/threads/405794-VHS-PAL-cutting-and-upscaling/page2

I thought it was nice to remind it

Did you read post #34? You must have glossed over it. I didn't point it out here because assumed the software the OP uses will automatically adjust when an HD resolution is shosen.

Do not cheat with me.

You ignored that requirement, as evident in post #25 https://forum.videohelp.com/threads/405794-VHS-PAL-cutting-and-upscaling#post2657684

Because you said in post #34 "I just couldn't see any difference at all with or without conversion, What are we looking at in terms of differences?" (differences that have been showed to you later) I was afraid you did not consider it here.

Never mind, not a problem at all.

[lollo]

For example, if one simply crops two lots of 8 pixels away to give 704x576, you end up with a distorted image at 4:3.

IIRC dellsam34 showed here a very nice example with a CD recording. Search for that thread

[Sharc]

"Required"? Why so?

read and study https://forum.videohelp.com/threads/405794-VHS-PAL-cutting-and-upscaling/page2

Tried this in VDub, no joy, it just spits out "BT470". Any suggestions?

No idea, sorry. I do not use VirtualDub or any other useless GUI for cropping/addborders/resizing/change matrix, just AviSynth, where you have full control. Maybe Sharc can help here...

No idea either. I used Virtualdub2 here for trying and verifying its functionality as discussed here in this thread, because the OP felt more comfortable with Vdub2 than with Avisynth. Normally I am using Avisynth, AvsPmod and Hybrid.
By the way, Vdub2 has an Avisynth editor (Tools tab) so one can use it similar to AvsPmod for developing Avisynth scripts.

[dellsam34]

Do not cheat with me.

You ignored that requirement, as evident in post #25 https://forum.videohelp.com/threads/405794-VHS-PAL-cutting-and-upscaling#post2657684

Because you said in post #34 "I just couldn't see any difference at all with or without conversion, What are we looking at in terms of differences?" (differences that have been showed to you later) I was afraid you did not consider it here.

Never mind, not a problem at all.

No, you're assuming too much here, I still don't see the difference in chroma for VHS sources, You showed me a snippet from my video that I digitized from a broadcast Betacam, 100 times better than VHS in terms of chroma, even with that, still there is no huge difference, I just do it because it's the legal way, Never said I wasn't doing it because I couldn't see a huge difference, Nice try though.

[lollo]

You showed me a snippet from my video that I digitized from a broadcast Betacam, 100 times better than VHS in terms of chroma, even with that, still there is no huge difference,

You do not see a big difference because you do not want to, but there is



And using a less washed-out reference the difference will be much higher: https://forum.videohelp.com/threads/405794-VHS-PAL-cutting-and-upscaling/page2#post2658172

[dellsam34]

Would you see the difference if you watched the two versions back to back? Highly unlikely.
We both agree there is a difference, I don't believe it's huge, and we are not going to change each other mind, so lets just leave at that and save this thread from derailing.

[lollo]

Would you see the difference if you watched the two versions back to back?

Yes

We both agree there is a difference, I don't believe it's huge, and we are not going to change each other mind, so lets just leave at that and save this thread from derailing.

Sure, it was just a (friendly) exchange of points of view.

[Alwyn]

Be careful with images generated by digital graphics machines back in the day such as Quantel machines, They don't have nor conform to a proper aspect ratio, The frame is usually smaller and padded with black borders, producers tend to stretch the image to fill the screen.

Does that mean that your general suggestion to crop 16 pixels off to get 704 then resize to 720 is not valid in all cases? It certainly doesn't appear to be in this case.

[jagabo]

Be careful with images generated by digital graphics machines back in the day such as Quantel machines, They don't have nor conform to a proper aspect ratio, The frame is usually smaller and padded with black borders, producers tend to stretch the image to fill the screen.

Does that mean that your general suggestion to crop 16 pixels off to get 704 then resize to 720 is not valid in all cases? It certainly doesn't appear to be in this case.

Nothing in video capture is true in all cases. If Dellsam43 is correct and the overlay does not conform to ITU specs, and your main interest is seeing the overlay with the correct aspect ratio, and possibly the live image in the background with the wrong aspect ratio, then yes, treat the full frame as 4:3.

One needs to find something in the live video that's of known aspect ratio to verify if the problem is just the overlay or the entire video or your capture device.

But Dellsam43 is correct: almost all capture devices follow the ITU spec with the 4:3 image in ~704 pixel wide portion of the frame with padding out to 720 pixels.

[Alwyn]

almost all capture devices follow the ITU spec with the 4:3 image in ~704 pixel wide portion of the frame with padding out to 720 pixels.

So, if the frame is "padded" out to 720, then any cropping of the sides (to get rid of the padding) must be accompanied by appropriate cropping of the top and bottom to maintain the correct aspect?

As shown in my example (ignore the foreground/background issue; it is now just a flat video with a circular object in the frame), if you don't crop top and bottom as well when taking off the 2 x 8 side pixels, you end up with a distorted frame.

[dellsam34]

As Jagabo mentioned before, out of 720x480 (576 in this case) only 704x480 (576) section is the 4:3 frame, So cropping 16 pixels out and flagging for 4:3 insures all devices will display it correctly, Some legacy devices such as DVD recorders and DV camcorders will automatically display the 704 out of 720 in the correct aspect ratio pushing the 16 pixels out of the 4:3 frame, I highly doubt newer devices do that, maybe some do, that's why resizing to a square pixel is hassle free.

Each one has its own method and the OP is free to do whatever please his eyes and works with his devices.

[Sharc]

Each one has its own method and the OP is free to do whatever please his eyes and works with his devices.

In practice one may want to crop more than 16 pixels total in order to fully remove the crud on the sides. In such case I crop as much as needed and add padding borders to make the frame width 704. I suggested this to the OP in post #238 for his particular video, using VirtualDub2 as his preferred tool as he doesn't feel comfortable with Avisynth yet.

Some legacy devices such as DVD recorders and DV camcorders will automatically display the 704 out of 720 in the correct aspect ratio pushing the 16 pixels out of the 4:3 frame, I highly doubt newer devices do that

My old player with analog (SCART, composite) interface to the TV did that, i.e. playing 720x576 "4:3" as 1.36:1 rather than 1.333:1. All newer players I have come across with HDMI interface output the full 720 frame as 4:3 and produce the well known ~2% aspect ratio error for ITU/Rec601 footage. Modern times.

[lollo]

Does that mean that your general suggestion to crop 16 pixels off to get 704 then resize to 720 is not valid in all cases?

So, if the frame is "padded" out to 720, then any cropping of the sides (to get rid of the padding) must be accompanied by appropriate cropping of the top and bottom to maintain the correct aspect?

There is nothing to crop on the bottom nor on the top and there is nothing to resize.

From the 720x576 frame captured frame, mask the switching head noise on the bottom, mask the bad lines on the top (if any) crop as needed on the left and on the right side, add borders to build the 704x576 frame. Encode with 4:3 DAR.

[Alwyn]

I'll be cropping and resizing so my frame is full image, not (sometimes uneven) black bars here and there, thank you very much. That is why I am asking about it, to get it right. And I will encode 768x576. KISS.

[Sharc]

From the 720x576 frame captured frame, mask the switching head noise on the bottom, mask the bad lines on the top (if any) crop as needed on the left and on the right side, add borders to build the 704x576 frame. Encode with 4:3 DAR.

Not for Alwyn's example which is a special case of a capture where the full 720x576 frame is 4:3, as the circle test reveals. The SAR (aka PAR) of his source is actually 16/15.
But I am afraid we are confusing the OP the longer the more with all our wisdoms ...

[lollo]

Yes, my comment was for a analog capture “in specification”. Let stop here 😄

[Leanoric]

Each one has its own method and the OP is free to do whatever please his eyes and works with his devices.

using VirtualDub2 as his preferred tool as he doesn't feel comfortable with Avisynth yet.

I'm not sure that I'll ever be comfortable with Avisynth. LOL

I've been experimenting with cropping and resizing with borders to 704x576, and cropping and then resizing to 1440x1080.

To be honest, they both look fine to my untrained eye. I'll probably just stick with the 1080 for now if its more compatible with modern tv's and media players.

[Sharc]

Happy to hear that you found your way

[jagabo]

Like I said earlier, crop by any amount you want and set the Sample Aspect Ratio when you encode (12:11 for a PAL ITU cap, 16:15 for a full frame non-ITU PAL cap). Let the player/TV/graphics card do the resizing for you.

[Sharc]

Like I said earlier, crop by any amount you want and set the Sample Aspect Ratio when you encode (12:11 for a PAL ITU cap, 16:15 for a full frame non-ITU PAL cap). Let the player/TV/graphics card do the resizing for you.

+1

I added the "padding luxury" for a standard frame size (704 x 576) only to ensure that the output looks the same when forcing the playback as 4:3 or letting the player/TV/graphics card do the resizing according to the SAR (Sampling Aspect Ratio). It can be seen as an unnecessary complication these days though.

[Leanoric]

I’m sorry to keep asking what are probably stupid questions but its got confusing again.


So if i crop and resize with borders to 704x576, set SAR to 12:11

If I crop and and resize to square pixels, 1440x1080 or 960x720, set SAR to 1:1

Im not sure when to set SAR to 16:15, when I crop and resize to 720x576?

[jagabo]

SAR 16:15 is for 720x576 videos that use the full frame (not a 704x576 portion) for the 4:3 DAR.

720 / 576 * 16 / 15 = 1.3333... = 4:3