Crop interlaced 4:3 letterbox to 16:9 DVD

[dave_van_damme]

Sorry, semi hijacked, no offence meant, just I fall asleep when all these methods are mentioned and i was trying to see if my simple idea found favour.

No problem!

[rrats]

Don't use DECOMB, use redudce framerate

[rrats]

Also will you send a short sample already

[ConsumerDV]

I would select "reduce frame rate" in IVTC filter to obtain native 24p.

[dave_van_damme]

Don't use DECOMB, use redudce framerate

Thanks

Also will you send a short sample already

I did! See post #29 https://forum.videohelp.com/threads/405948-Crop-interlaced-4-3-letterbox-to-16-9-DVD#post2658515

I would select "reduce frame rate" in IVTC filter to obtain native 24p.

Nice - thank you.

[ProWo]

Use clever FFmpeg-GUI, the newest beta. https://files.videohelp.com/u/292773/clever_ffmpeg_gui_newest_beta.7z

Load your video, click main, click convert video stream, click crop detect, execute crop detection and preview until you see the video picture only (without black bars), then click ok.

Thanks but its LAGS AVI and won't load in FFmpeg-GUI.

Ffmpeg should decode Lagarith...

[rrats]

I did! See post #29 https://forum.videohelp.com/threads/405948-Crop-interlaced-4-3-letterbox-to-16-9-DVD#post2658515

Sorry that post slipped right past through me

[jagabo]

Unfortunately, there are subtitles in the letterboxed portion which need to be cut out. Is there an easy way to crop all of the letterbox region and re-create the black bars in order to keep the correct aspect ratio?

Instead of cropping to 704x360, crop all the black bars. That will leave you with 704x288. Then, before resizing to 704x480, add a Resize filter and use only the lower portion of the dialog to Letterbox/Crop To Size 704x360. That will add black letterbox bars to give you a 704x360. Then add another Resize filter to resize to 704x480.

And yes, you should reduce the frame rate when you IVTC. Otherwise you will end up with a duplicate frame every 5 frames. And specify Top Field First since your video is TFF.

Why is your sample 708x360?

[Skiller]

Unfortunately, there are subtitles in the letterboxed portion which need to be cut out. Is there an easy way to crop all of the letterbox region and re-create the black bars in order to keep the correct aspect ratio?

Yes, you may use the filter "fill" in VirtualDub for that. It does what the name suggests, fill an area you define with a solid color (default: black). This is a good idea anyways as to kill any noise in the remaining letterbox bars.

However, there are many way to do this and jagabo's approach is just as good. Whatever you prefer.

[dave_van_damme]

Unfortunately, there are subtitles in the letterboxed portion which need to be cut out. Is there an easy way to crop all of the letterbox region and re-create the black bars in order to keep the correct aspect ratio?

Instead of cropping to 704x360, crop all the black bars. That will leave you with 704x288. Then, before resizing to 704x480, add a Resize filter and use only the lower portion of the dialog to Letterbox/Crop To Size 704x360. That will add black letterbox bars to give you a 704x360. Then add another Resize filter to resize to 704x480.

And yes, you should reduce the frame rate when you IVTC. Otherwise you will end up with a duplicate frame every 5 frames. And specify Top Field First since your video is TFF.

Great, thank you for the instructions! Here's my filter chain:


[Attachment 65203 - Click to enlarge]

A few questions:
1. I cropped to 705x287 because when I chose 704x288 a tiny bit of the picture information was cut. Will that mess up the aspect ratio?
2. Was I right to use Lanczos3 to re-size or should I use a different setting?
3. When cropping should I use YCbCr "Precise" or "Fast"?
4. For the re-size to 704x480, I can only get it to that size if I set "Aspect Ratio" to "Disabled" - is that the correct method or is there something else I should be doing?
5. I'd like to add some filters for cleaning up the video (Dot crawl filter and frequency suppressor of the noise). Where should I place them in the filter chain?
6. If I wanted to produce the video without any letterbox bars and make it 16:9, how would I go about doing that and maintaining the correct AR?

Here's a screenshot with the settings you suggested:

[Attachment 65204 - Click to enlarge]

Why is your sample 708x360?

Whoops, my bad. I was messing with filters and forgot to delete them.

I've uploaded the untouched video ("Original.avi") and the processed version ("Filtered.avi"). Please excuse the burned in Closed Captions - I'm doing this for an elderly person who requires burned-in subs.

Thanks for all the help with this.

[ConsumerDV]

6. If I wanted to produce the video without any letterbox bars and make it 16:9, how would I go about doing that and maintaining the correct AR?

It is like the above offtopic discussion went right pass you.

BTW, is it a 1992 movie? You can buy a proper widescreen DVD on eBay for mere $3 including shipping, or for $5 new on Amazon, or for $10 new Blu-Ray which will trump your Laserdisc copy.

EDIT: Maybe you have a point, converting the Laserdisc version. Reading reviews on Amazon, I found this, so maybe get a Blu-Ray instead.

[DB83]

The crop to 704*... is technically correct if there are exactly 8 pixels of black to the left of the active picture and 8 pixels to the right. This is rarely the case in a real scenario and you have to manually set the parameters.

Will it alter the AR ?. No*. Since the reference is to the actual displayed size and not the stored size of 720 (thus reduced to 704). Leaving the horizontal at 720 which I originally suggested does make a slight alteration to the AR. But one that is not typically noticed.


However altering the vertical crop WILL alter the AR due to the above.


And due to the above you can not create a dvd without any letter-boxing bars since there are only two legal DAR's namely 4*3 and 16*9 unless you want to remove information typically left and right which is how such films used to be shown on tv way back when. If the tv did it right they would pan+scan the active image yet typically you just got a fixed focus.

*edit: If you go significantly below 704 there will be an effect on the AR since the image will now be disproportionally stretched

[DB83]

And allow me to throw a little spike in to the wheel.

I state this since I have not checked any of the samples so posted.


Whilst it is true that the original AR of the film is 2.35:1, what you see on your LD/capture may be not. I state this from experience inasmuch that I have a VHS that could have been that AR or even 2.20:1 yet the VHS and the dvd of the same film have slightly different information and this is not uncommon. To get what you see and at the right AR you would have to crop all the black bars, resize to how it would look and then do your sums.

[dellsam34]

Yes, there are exactly 8 black pixels in total. Also if the OP wants to keep black bands on top and bottom of the frame he will have black bands on all 4 sides of the 16:9 screen, If an old school 4:3 TV is used this is not an issue. So utilizing the whole frame with very thin black stipes on top and bottom to keep the aspect ratio 704:360 is the ideal option for a 16:9 display as Jagabo mentioned and I illustrated in post #8, Good luck.

[jagabo]

1. I cropped to 705x287 because when I chose 704x288 a tiny bit of the picture information was cut. Will that mess up the aspect ratio?

I just did a quick crop when I came up with 704x288. Whether your 287 lines is closer to correct or not will not make much of a difference in the final aspect ratio, less than 1/2 a percent, not worth worrying about. Another possible issue is the chroma subsampling. Generally, YUV 4:2:2 video (what you have) should be cropped by even values at the left edge. YUV 4:2:0 should be cropped by even values at the left top edges. Otherwise you will get a little blurring of the colors. That's not probably not an issue here since the video isn't very sharp to begin with.

2. Was I right to use Lanczos3 to re-size or should I use a different setting?

Your source isn't very sharp so Lanczos3 is probably fine. It's the sharpest of the resizers in VirtualDub and will produce oversharpening halos at very sharp edges -- especially at the boundary between the active picture and black borders. And it will increase noise the most.

You can prevent the edge halos by cropping away all of the black borders, resizing, then upscaling and adding borders. So crop to ~704x286, then upscale to ~704x382 and add borders to 704x480. The last two can be done in one Resize filter in VirtualDub. This will also purify the black borders which are a bit noisy in your source (noise eats up bitrate, pure unchanging black doesn't).

How did I come up with the 704x382 upscale? You can do the math, or you can do it experimentally:

crop to 704x360 # standard 4:3 to 16:9 conversion
resize to 704x480 # standard 4:3 to 16:9 conversion
use the crop filter to find size of the active picture (~704x382)

You now know that when you upscale the fully cropped video the picture needs to be 704x382 before adding black borders. This means the top and bottom black borders will be 49 lines high. When you make a DVD you will get slightly off colors at the boundary between the picture and borders (from the YV12 subsampling). So in practice you may want to upscale to 704x380 (50 lines of black top and bottom) or 704x384 (48 lines of black top and bottom) to prevent that.

3. When cropping should I use YCbCr "Precise" or "Fast"?

Given everything else you're doing the difference in speed will be minimal. So there's no reason not to use precise.

4. For the re-size to 704x480, I can only get it to that size if I set "Aspect Ratio" to "Disabled" - is that the correct method or is there something else I should be doing?

That is the correct procedure. We are intentionally changing the aspect ratio to convert from 4:3 to 16:9.

5. I'd like to add some filters for cleaning up the video (Dot crawl filter and frequency suppressor of the noise). Where should I place them in the filter chain?

I haven't used either of those in VirtualDub so I don't know for sure. But usually dot crawl filters work best on the original interlaced video. So you probably want that at the start (before IVTC). Noise reducers usually work better with progressive frames and before scaling. So I would use:

dot crawl reduction
IVTC
crop to 704x286
general color correction
general noise reduction filters
resize to 704x382 and add borders to 704x480

6. If I wanted to produce the video without any letterbox bars and make it 16:9, how would I go about doing that and maintaining the correct AR?

DVD only supports 4:3 and 16:9 aspect ratios. So it's not possible to fit an entire 2.35:1 frame without any black bars. Unless you crop the width or distort the picture. Cropping would give a picture something like:


[Attachment 65215 - Click to enlarge]

The dark part of the image is what would be cropped if you crop equal amount from both sides. Ie, the full image is the 2.35:1 frame, the bright part is a 16:9 portion of that frame.

[dellsam34]

Don't you think resizing from 360 to 480 is damaging since the resolutions are too close to each other? I would resize directly to 1920x1080 and add the necessary borders to keep the frame intact if a HD TV is to be used for playback:


[Attachment 65206 - Click to enlarge]

[DB83]

^^ As per the title etc., the OP intends to create a DVD. 1080i/p is a non-starter.

[dellsam34]

That contradicts the reasoning of some purists who resisted DVD because of its lower quality and they stayed with LaserDisc, It's ironic to see one that thinks otherwise and converts laser discs to it.

[DB83]

Well the OP has stated that he is doing this for, I assume, a relative.

Probably thinks it is worthwhile since the relative may only watch it once rather than acquire the actual commercial dvd (I have many a dvd that I have watched only once )


And burning in the subs takes away the issue that the relative may have in accessing them in normal cirumstances.

[davexnet]

Probably see a significant drop in quality via the resizing and compression with mpeg-2.
The OP posted "original" and "filtered" both Lagarith. I supposed that's one way to do it,
lossless intermediate then convert to DVD

[dave_van_damme]

1. I cropped to 705x287 because when I chose 704x288 a tiny bit of the picture information was cut. Will that mess up the aspect ratio?

I just did a quick crop when I came up with 704x288. Whether your 287 lines is closer to correct or not will not make much of a difference in the final aspect ratio, less than 1/2 a percent, not worth worrying about. Another possible issue is the chroma subsampling. Generally, YUV 4:2:2 video (what you have) should be cropped by even values at the left edge. YUV 4:2:0 should be cropped by even values at the left top edges. Otherwise you will get a little blurring of the colors. That's not probably not an issue here since the video isn't very sharp to begin with.

2. Was I right to use Lanczos3 to re-size or should I use a different setting?

Your source isn't very sharp so Lanczos3 is probably fine. It's the sharpest of the resizers in VirtualDub and will produce oversharpening halos at very sharp edges -- especially at the boundary between the active picture and black borders. And it will increase noise the most.

You can prevent the edge halos by cropping away all of the black borders, resizing, then upscaling and adding borders. So crop to ~704x286, then upscale to ~704x382 and add borders to 704x480. The last two can be done in one Resize filter in VirtualDub. This will also purify the black borders which are a bit noisy in your source (noise eats up bitrate, pure unchanging black doesn't).

How did I come up with the 704x382 upscale? You can do the math, or you can do it experimentally:

crop to 704x360 # standard 4:3 to 16:9 conversion
resize to 704x480 # standard 4:3 to 16:9 conversion
use the crop filter to find size of the active picture (~704x382)

You now know that when you upscale the fully cropped video the picture needs to be 704x382 before adding black borders. This means the top and bottom black borders will be 49 lines high. When you make a DVD you will get slightly off colors at the boundary between the picture and borders (from the YV12 subsampling). So in practice you may want to upscale to 704x380 (50 lines of black top and bottom) or 704x384 (48 lines of black top and bottom) to prevent that.

3. When cropping should I use YCbCr "Precise" or "Fast"?

Given everything else you're doing the difference in speed will be minimal. So there's no reason not to use precise.

4. For the re-size to 704x480, I can only get it to that size if I set "Aspect Ratio" to "Disabled" - is that the correct method or is there something else I should be doing?

That is the correct procedure. We are intentionally changing the aspect ratio to convert from 4:3 to 16:9.

5. I'd like to add some filters for cleaning up the video (Dot crawl filter and frequency suppressor of the noise). Where should I place them in the filter chain?

I haven't used either of those in VirtualDub so I don't know for sure. But usually dot crawl filters work best on the original interlaced video. So you probably want that at the start (before IVTC). Noise reducers usually work better with progressive frames and before scaling. So I would use:

dot crawl reduction
IVTC
crop to 704x286
general color correction
general noise reduction filters
resize to 704x382 and add borders to 704x480

6. If I wanted to produce the video without any letterbox bars and make it 16:9, how would I go about doing that and maintaining the correct AR?

DVD only supports 4:3 and 16:9 aspect ratios. So it's not possible to fit an entire 2.35:1 frame without any black bars. Unless you crop the width or distort the picture. Cropping would give a picture something like:


[Attachment 65215 - Click to enlarge]

The dark part of the image is what would be cropped if you crop equal amount from both sides. Ie, the full image is the 2.35:1 frame, the bright part is a 16:9 portion of that frame.

Thank you - I really appreciate all the help and the explanations you've given! A lot for me to digest and to understand.

I made the attached demo using the settings you suggested:
IVTC (reduce frame rate, TFF)
crop to 704x286
resize to 704x382
add borders to 704x480

This produced a 23.976fps video (attached), however, there are some interlace artifacts. I assumed with the IVTC that this wouldn't happen?

[Attachment 65245 - Click to enlarge]

BTW, is it a 1992 movie? You can buy a proper widescreen DVD on eBay for mere $3 including shipping, or for $5 new on Amazon, or for $10 new Blu-Ray which will trump your Laserdisc copy.

EDIT: Maybe you have a point, converting the Laserdisc version. Reading reviews on Amazon, I found this, so maybe get a Blu-Ray instead.

Yeah, they specifically want the Theatrical Version with the subtitles for the native dialogue, which I believe the DVD/BR are missing. This is my first attempt to properly digitize an LD so it's a learning curve for me, but I have several rare/OOP discs from my collection I plan on digitizing so it's good to try to get some practice!

[Skiller]

This produced a 23.976fps video (attached), however, there are some interlace artifacts. I assumed with the IVTC that this wouldn't happen?

Yes, it should not happen, but IVTC is not necessarily an easy task. To begin with, VirtualDub's internal IVTC filter is not very tweakable and pales in comparison to what control you have over this in AviSynth using TIVTC.

However, it might help, or even completely fix it, if you crop first (before IVTC) as the black bars may fool the pattern detection. Be aware that cropping the top by an uneven number changes the field dominance.

[jagabo]

I made the attached demo using the settings you suggested:
IVTC (reduce frame rate, TFF)
crop to 704x286
resize to 704x382
add borders to 704x480

This produced a 23.976fps video (attached), however, there are some interlace artifacts. I assumed with the IVTC that this wouldn't happen?

The IVTC is failing in many places. It looks like the subtitles are confusing it (the subs were overlaid after the film was telecined and have a different cadence). I confirmed this with the earlier video sample.

If you have a perfect capture (no drop or inserted frames) you can use the IVTC filters's manual setting rather than the adaptive setting. With your sample clip an offset of 3 works perfectly (occasionally the subs will be combed). If there are breaks in the telecine pattern you will have to work in segments. That's OK if there's only a few breaks in the movie but it will be a lot of work if there are dozens or hundreds.

Another possible trick is to first apply the Deinterlace filter with Yadif + Keep Top Field... then add the IVTC filter. This basically uses Yadif to remove the combing then IVTC to decimate. I tried this with the earlier sample and it got rid of the combing but the video was a little jerky (imperfect decimation). I should point out that this is not the preferred method of performing an IVTC but in a case like this you may need it.

[dave_van_damme]

Thank you both for the suggestions, I'll try a few of the options and see what works best. I had no idea that subtitles would cause confusion nor that a few inserted frames could also cause problems (I think there's about 10 inserted frames altogether).

I've captured a lot of VHS tapes in the past but never done IVTC before. For my YouTube channel I've always used Yadif: Field: Temporal & Spatial Check in Avidemux (I guess it's labelled as "Double Frame Rate: Keep Top Field" in VDub). Is there any reason why I couldn't use Yadif for this project or is IVTC recommended because restores the intended frame rate?

[ConsumerDV]

Deinterlacing with doubling frame rate always works. It is the default method of all TV sets. IVTC is preferred if it is applicable because it allows to recover full vertical resolution.

[Skiller]

That works, but for DVD you would then have to re-interlace after resizing, as double framerate is not possible on DVD. The filter that does that in VirtualDub is called "interlace".
There's nothing majorly wrong in doing it that way – it basically puts the fields back like they were on Laserdisc, except resized. So there is no chance of residual combing or jerky motion. The downside is the resizing suffers a bit in quality because it is working on former fields, deinterlaced to frames with mediocre quality by Yadif (so no full vertical resolution), rather than the full quality frames you get with IVTC.

Oh and of course the resulting video is interlaced which makes it harder to encode. But it's an option if IVTC doesn't bring good results.