Downrezzing Advice

[SameSelf]

Resizing to 704 and then adding borders for 720 is in line with the ITU Rec.601 spec. Some people say this spec does not (should not) apply to DVD-Video, while I think the true thing is it applies whenever video is converted between analog and digital (either direction) which nowadays with HDMI and modern TVs is of course not the case, so I admit there is a point in calling it wrong (but then again I could say the HDMI spec is wrong).

Anyways, to avoid the whole hassle of it I would skip the borders and simply encode at 704x576, because that is just as DVD-compliant as 720x576.
704x576 with 16:9 DAR, easy, no sweat and in line with all specs.

Wow, I didn't realize that 576 lines was an NTSC DVD compliant vertical resolution. I have seen that numerous times here and at doom9 and just assumed that it was some PAL spec and that NTSC was always 720x480. I am all about keeping as much of my vertical resolution as possible. And I agree with your point, worrying about analog compatibility in today's all digital world is unnecessarily pedantic.

So, if I understand correctly, 704x576 SAR equates to a 16:11 PAR for a 16:9 DAR in NTSC space?

[SameSelf]

I wouldn't worry about flicker since your source is progressive and nobody watches on a CRT anymore. But watch out from oversharpening halos, buzzing edges, aliasing, moire artifacts, increased noise, and the other ills of too much sharpening.

Thanks for confirming my suspicions. I will test how it looks without any blurring or sharpening. You guys are great. Helping me go from a clumsy, ill-informed attempt to get my video onto a DVD to something that is Oscar worthy!

[KarMa]

Going back and checking, seems like my 16:9 store bought DVDs follow a DAR of ~1.82. Some using bars on the left and right of the video, others seem to have cropped down to an AR of ~1.82 before downsizing to 720x480. Have not found any 16:9 NTSC DVDs with 704x480, just 720x480.

Wow, I didn't realize that 576 lines was an NTSC DVD compliant vertical resolution.

I don't think so, not with a standard player.

[Skiller]

And I agree with your point, worrying about analog compatibility in today's all digital world is unnecessarily pedantic.

That wasn't really my point, I actually worry about analog compatibility more than most people do and I love being pedantic about it (heck, I still use a CRT TV every day), but my point was any discussion about whether the ITU spec is wrong or right is pretty much moot if we consider encoding a frame size of 704x576 or 704x480.

So, if I understand correctly, 704x576 SAR equates to a 16:11 PAR for a 16:9 DAR in NTSC space?

No, 576 lines is only for PAL DVDs, I just happen to write 576 instead of 480 most of the time being a PAL user. It would be 704x480 for an NTSC DVD then. Sorry for the inconvenience.

Have not found any 16:9 NTSC DVDs with 704x480, just 720x480.

Commercial discs pretty much never use it. I have never witnessed a single one.
Edit: I believe this is because in the professional field this whole topic is widely ignored. "720. End of story."

I wouldn't worry about flicker since your source is progressive

interlaced playback chain

[SameSelf]

I actually worry about analog compatibility more than most people do and I love being pedantic about it (heck, I still use a CRT TV every day), but my point was any discussion about whether the ITU spec is wrong or right is pretty much moot if we consider encoding a frame size of 704x576 or 704x480.

576 lines is only for PAL DVDs, I just happen to write 576 instead of 480 most of the time being a PAL user. It would be 704x480 for an NTSC DVD then. Sorry for the inconvenience.

Have not found any 16:9 NTSC DVDs with 704x480, just 720x480.

Commercial discs pretty much never use it. I have never witnessed a single one.
Edit: I believe this is because in the professional field this whole topic is widely ignored. "720. End of story."

I wouldn't worry about flicker since your source is progressive

interlaced playback chain

Thanks for the PAL vs NTSC clarification. 480 lines it is for me.

As for the 704 vs 720 debate. Here are my thoughts:

Since I am starting out with square pixels, the most accurate square pixel resizing for 480 lines at true 16:9 would be 853 and 1/3 pixels. But there is no such thing as 1/3 pixel. So, scaling down to either 704 or 720 is probably immaterial because the transformation is not without error anyway.

It seems to me that it comes down to what will be done with the extra 16 pixels. If they get displayed, by all means use them, amiright? I know for a fact that my home DVDs made from SD analog sources captured at 704x480, the black bars on the left and right are visible on my modern HDTV. But since there is no extra information in my SD videos that I am discarding, there is no point in scaling up to 720. But that is not the case with my HD video.

EDIT: and this leads me to think that the reason commercial DVDs use all 720 pixels is because it is more aesthetically pleasing versus seeing black bars on the edges which might make people think something is wrong with their TV, or worse, the DVD. Use the whole screen for crying out loud! I didn't pay all this money for my giant TV to see some of the real estate go unused! LOL

[smrpix]

this leads me to think that the reason commercial DVDs use all 720 pixels is because it is more aesthetically pleasing versus seeing black bars on the edges..

Actually, it's because when you enter the digital realm 720 happens to be a mathematically convenient, useful and flexible number, just as 16x9 (4squared x 3squared) is mathematically convenient.

[smrpix]

...answered wrong question...

[Skiller]

EDIT: and this leads me to think that the reason commercial DVDs use all 720 pixels is because it is more aesthetically pleasing versus seeing black bars on the edges which might make people think something is wrong with their TV, or worse, the DVD. Use the whole screen for crying out loud!

704x480/576 does "use the whole screen" by all definitions.
It's 720 where things aren't so clear. You're not going to get any bars but there may be a small aspect ratio error of exactly that ratio (720 <-> 704), which is admittedly small and thus so widely ignored.

[jagabo]

In my experience using upscaling players via HDMI the "extra" 16 pixels at the edges of the 720x480 frame are displayed on a 1920x1080 HDTV if you have the TV set to show 1920x1080 input pixel-for-pixel. Ie, the 16:9 DAR 720x480 frame is enlarged directly to 1920x1080 an sent to the TV. If the TV is set to overscan (the default on most TVs) you do not see the edges of the frame so you won't see 8 pixel thick black bars at the left and right edges. Of course, the top and bottom edges are cut off by overscan too. It's been 10 years since I've tested analog output, and it was only a handful of DVD players that I tested, but at the composite output the black borders fall in the front and back porch of the signal. So the composite signal conforms to the ITU spec. Analog TVs all overscanned (except some studio monitors) so you did no see the black borders (or active picture) in the porches.

This problem comes about because the DVD spec refers to the the MPEG 2 for aspect ratios. The MPEG 2 stream only includes DAR information for 4:3 and 16:9 video (the only two allowed for DVD). The MPEG 2 spec clearly states that the full frame contains the indicated DAR. This is at odds with the internationally agreed upon ITU spec which captures analog sources with the the 4:3 or 16:9 DAR in a ~704 pixel wide portion of the frame (usually a full 720 pixels are captured in case the picture is off center). I suspect this is the reason 704x480 was included as part of the DVD spec -- so sticklers for aspect ratio could correctly master their ITU caps. But nobody in the industry seems to care. I've never seen a commercial DVD at 704x480. And the vast majority of 4:3 DVDs made from analog tape sources were capture following the ITU spec and are put on DVD without adjusting for the MPEG 2 spec.

[KarMa]

But how would a 704x480 video be seen over composite, wouldn't it be stretched horizontally?

[Skiller]

But how would a 704x480 video be seen over composite, wouldn't it be stretched horizontally?

No, actually a 720x480 video without the 8px black bars at the left and right sides would be slightly stretched over Composite.

Following the ITU-spec, 704 is a cropped version of 720 (not resized), already containing the entire active picture (the whole 4:3 or anamorphic 16:9 area, nothing missing). So in return 720 carries some non-picture overhead (usually black).

If the TV is set to overscan (the default on most TVs) you do not see the edges of the frame so you won't see 8 pixel thick black bars at the left and right edges.

Have you ever tested what happens if the source picture is 704x576/480? Does it get resized straight to 1920x1080 as well?

[_Al_]

I think those are marginal errors for studios, if having 720x480, there could be borders, it does not have to be a strict 16 pixels within 720, mostly just something.

But nobody in the industry seems to care.

I can see a black bars a lot, extras on Blu-Ray actually, within 720x480 resolution, is it made the same way as DVD's? Not necessarily 8 and 8, mostly those black borders are shifted to like 4 and 12, or 2 and 8 or something so mostly those black borders are not as total of 16 pixels , but just something , I realized this by having backing up extras to mkv from Blu-Rays enabling autocrop, and that could give me a weird width a lots of time, so for SD extra is definitively better to turn off autocrop (if script does it all automatically and encodes).

btw., off topic, there could be 2pixel of black border even on Blu-Ray title, perhaps animation mostly, not sure now, so the same thing, if using autocrop, script it in a way, so it turns off autocrop if those borders are less than 10 pixel or something, if are negligible.

[jagabo]

Have you ever tested what happens if the source picture is 704x576/480? Does it get resized straight to 1920x1080 as well?

I just made a DVD and tested it on my LG BD670 Blu-ray player with the player upscaling to 1080p. Both 720x480 and 704x480 16:9 DAR get upscaled to 1920x1080. Every pixel of both sources is visible and they completely fill the 16:9 TV screen (no overscan on the TV, I used test patterns that would show if part of the picture was cut off). 4:3 DAR both fill a 4:3 portion of the screen (1440x1080) and every pixel of the DVD is visible. So that player follows the MPEG spec.

Sample 704x480 image used:

[Cornucopia]

IME, this is such a non-issue that I find this protracted discussion about it a bit absurd & anal-retentive.

Scott

[jagabo]

IME, this is such a non-issue that I find this protracted discussion about it a bit absurd & anal-retentive.

Me too. Nobody can see the AR difference. And if you spend all your time watching any black borders you're not paying attention to the movie.

[SameSelf]

I just made a DVD and tested it on my LG BD670 Blu-ray player with the player upscaling to 1080p. Both 720x480 and 704x480 16:9 DAR get upscaled to 1920x1080. Every pixel of both sources is visible and they completely fill the 16:9 TV screen (no overscan on the TV, I used test patterns that would show if part of the picture was cut off). 4:3 DAR both fill a 4:3 portion of the screen (1440x1080) and every pixel of the DVD is visible. So that player follows the MPEG spec.

Great work jagabo! Thanks for testing that. That seems to indicate what I thought, that modern players and TVs, via HDMI, display the full 720 pixels. Please feel free to correct me, if I am misstating your results.

Interestingly, DVD Architect allows one to choose between 720x480 or 704x480 NTSC. So I tested a quick 704x480 encode, and brought it into DVDA and it accepted the file without triggering a re-encode. Encore complains.

Since I am planning to use DVDA anyway, AddBorders is not needed. No need to conform to 720. Or is there?

Since you are aiming for 16:9 you need all the horizontal resolution you can get, and I think those boarders would screw with the displayed aspect ratio. I would just resize down to 720x480 without addboarders(). Maybe someone can add to this if I missed anything.

Is there something magical about the resize down to 704x480 in the Avisynth filter? I am guessing it doesn't really matter if you specify 704 or 720? So the burning question in my mind is, do I gain or lose anything by resizing to 720?

[jagabo]

That seems to indicate what I thought, that modern players and TVs, via HDMI, display the full 720 pixels.

Yes, that is correct.

Is there something magical about the resize down to 704x480 in the Avisynth filter? I am guessing it doesn't really matter if you specify 704 or 720?

720 retains a tiny bit more detail.

[SameSelf]

Cool. So all that is left, is to determine how much, or not at all, sharpening and blurring I need.

[_Al_]

Interestingly, DVD Architect allows one to choose between 720x480 or 704x480 NTSC. So I tested a quick 704x480 encode, and brought it into DVDA and it accepted the file without triggering a re-encode. Encore complains.

In that regard, I think Vegas might be the only videoeditor that even cares about this mpeg2 specs, and all this "little madness", it can even render 720x480 with those 8 pixels black to left end right to keep aspect ratio, only to surprise a lot of people and there were a heated discussions about that as well.

For example,
1. loading 720x480 jpg into NTSC DVavi project, you'd get black bars on top and bottom! Vegas assumes it is square pixel, you need to apply "4:3 standard TV aspect ratio" in pan/crop, only to get 8pixel black on left and right. If those black bars left and right are not desired, "Maintain Aspect ratio" has to be set to NO in pan/crop.
2. Loading 720x480 jpg or png made in Photoshop's 720x480 DV template has to be fixed with Maintain aspect ratio to NO in pan/crop.

No need to look for any effects, zooming or playing inpan/crop to drag borders to correct image manually , it will not let you easy anyway, almost like there is "safety on" in there or something. Vegas just talks "Pro" language. All of this is correct but this sort of things could throw off a lot of people saying it is too difficult and obnoxious

Loading DVavi video would not cause any black bars, it assumes it has DV avi aspect ratio already.

[hello_hello]

Have not found any 16:9 NTSC DVDs with 704x480, just 720x480.

Commercial discs pretty much never use it. I have never witnessed a single one.
Edit: I believe this is because in the professional field this whole topic is widely ignored. "720. End of story."

Since I am planning to use DVDA anyway, AddBorders is not needed. No need to conform to 720. Or is there

704x480 and 704x576 aren't legal resolutions for 16:9 DVDs, only 4:3.
https://en.wikipedia.org/wiki/DVD-Video#Video_data
Video with 4:3 frame aspect ratio is supported in all video modes. Widescreen video is supported only in D-1 resolutions.

I recall reading a thread about it ages ago (probably doom9) and someone said they'd tested a few DVD players and they hadn't refused to play 704x480 16:9 DVD video, but still, it's not a "legal" 16:9 DVD resolution.

[hello_hello]

IME, this is such a non-issue that I find this protracted discussion about it a bit absurd & anal-retentive.

Scott

Wow.... that's odd, coming from the forum champion of industry standards and not daring to deviate from them.

[jagabo]

If anyone want's to try the frame size vs. aspect ratio tests on their player/TV here's an ISO image (in a ZIP archive) ready for DVD. Warning: no audio, cheesy menu.

[Cornucopia]

IME, this is such a non-issue that I find this protracted discussion about it a bit absurd & anal-retentive.

Scott

Wow.... that's odd, coming from the forum champion of industry standards and not daring to deviate from them.

No it's not.

When the standards are clearly defined and regularly, properly adhered to, it makes sense to adhere to them also (if you intend for your work to be compatible beyond the bounds of just your own home - that's one area where you and I seem to differ, as I am a working media production professional, not just a knowledgeable hobbyist).
But this standard isn't even adhered to by the industry.
Internally, it's still a standard I will try to follow on my own and will recommend to people, but it's pointless to argue the details of this beyond "treat the source footage with respect" (and "use good judgement" as my mom would say) when the outcome of those different tactics are often muddied by playback hardware anyway.

It's not a topic like "multitrack audio channel order", where the wrong method's outcome is glaringly obvious, and where standards have finally become clear and well-adhered to.


Scott

[SameSelf]

IME, this is such a non-issue that I find this protracted discussion about it a bit absurd & anal-retentive.

Scott

Wow.... that's odd, coming from the forum champion of industry standards and not daring to deviate from them.

Corny was marginally helpful in the past, but now just flames my threads regularly rather than adding to the discussion. I am guessing he holds a grudge against me personally for some reason. The only other post in this thread:

Yeah, I'm tired of getting drowned out by newbies who don't even want to understand, and yet still think they know better/more. I only partly put up with that from my own kids!

Scott

On a brighter note, that Wiki link seems to offer the greatest clarity (I think). According to Wiki, the DVD-Video spec "is not publicly available and every subscriber must sign a non-disclosure agreement. Certain information in the DVD Book is proprietary and confidential." Wow. I hope no lawyers come knocking on my door for discussing this.

So, for NTSC land, 704x480 and 720x480 (D-1) are both legal resolutions for 4:3 AR unless you are dealing with 16:9 widescreen video, then only D-1 is the legal DVD-Video spec, per the Wiki article. What it doesn't say is whether 8 pixel wide black bars are expected to be present on the left and right for widescreen. So, while my first Avisynth code with the AddBorders was correct from a DVD-Video specification standpoint:

1. It probably was a bigger concern in the early days of DVD players and analog TV with overscan.
2. Modern players probably don't care. This is likely do to wide DVD-R/+R support.
3. Digital TV with native progressive screens and HDMI has changed every thing. And for the better I might add.

However, now I am going to appeal to you gurus for some different kind of help.

My downscaling looks terrible! There is a massive amount of ringing present. I have tried the following Avisynth scripts using HCenc:

AVISource("E:\SDTest.avi", audio=false).AssumeFPS(30000,1001).ConvertToYV12(interlaced=false, matrix="rec601")
Sharpen(0.5, 0) #pre-sharpen horizontally to better keep hor. details
BlackmanResize(720, 480, taps=4) #for AviSynth versions before 2.58 use Spline36Resize
##Low pass filter to eliminate interline-twitter
#Blur(0, 0.6, false).Sharpen(0, 0.4, false) #mild, not for very detailed sources
Blur(0, 0.7, false).Sharpen(0, 0.4, false) #medium, works well with almost any source in my experience
#Blur(0, 0.9, false).Sharpen(0, 0.5, false) #strong, try medium first

And simply:

AVISource("E:\SDTest.avi", audio=false).AssumeFPS(30000,1001).ConvertToYV12(interlaced=false, matrix="rec601")
BlackmanResize(720, 480, taps=4) #for AviSynth versions before 2.58 use Spline36Resize

So here is a snippet of the video. It is a Lagarith lossless intermediate encoded as YUY2. Don't worry. It really is widescreen, I just masked off some identifying features on the sides.

[jagabo]

According to Wiki, the DVD-Video spec "is not publicly available and every subscriber must sign a non-disclosure agreement. Certain information in the DVD Book is proprietary and confidential."

Yes. Someone with access to the DVD spec once reported here that it refers to the MPEG 2 spec regarding aspect ratios. The MPEG 2 spec is available (at least a draft version) for download. Search for ISO13818-2.

My downscaling looks terrible!

Try just BilinearResize(720,480) for downscaling and blurring.

<edit>

Your sample finished downloading. Jeez, it's way oversharpened even before scaling. BilinearResize isn't enough blurring to undo that. Try dehalo_alpha(rx=2, ry=1, darkstr=1.5, brightstr=1.5), then BilinearResize.

</edit>

[Skiller]

My downscaling looks terrible! There is a massive amount of ringing present.

Ringing as in "mosquito noise" after compression to MPEG2 or ringing like the ringing of a sharp resizer?

What do you think of this, downscaled and encoded for NTSC DVD? I don't see any problems with this, it looks very good to me.



Edit:

So, for NTSC land, 704x480 and 720x480 (D-1) are both legal resolutions for 4:3 AR unless you are dealing with 16:9 widescreen video, then only D-1 is the legal DVD-Video spec, per the Wiki article.

I followed that discussion at the time and if I remember correctly this player that didn't play 704x576/480 16:9 was made in 2001 and it is the only one ever reported. For me this doesn't confirm that only 720x576/480 is valid for 16:9 – it could have been a firmware bug in that player.

Personally I'm convinced you will not find a single player that does not play 704x576/480 just because it's 16:9.

[hello_hello]

It's not a topic like "multitrack audio channel order", where the wrong method's outcome is glaringly obvious, and where standards have finally become clear and well-adhered to.

First newbies don't want to understand, then trying to understand is being absurd and anally retentive.....

It's probably not a topic like "putting progressive video on a DVD" either, where we're still waiting to find out what you tell your kids about that one.

[SameSelf]

Try just BilinearResize(720,480) for downscaling and blurring.

<edit>

Your sample finished downloading. Jeez, it's way oversharpened even before scaling. BilinearResize isn't enough blurring to undo that. Try dehalo_alpha(rx=2, ry=1, darkstr=1.5, brightstr=1.5), then BilinearResize.

</edit>

Thanks for taking a look. I will give your suggestion a shot. Can you explain what you mean by way oversharpened? Maybe you It was a while ago when I comped this video. I went back and looked at the AE comp. There is no sharpening specifically. Rather, there is a RemoveGrain effect applied because my camcorder is very noisy even in well lit conditions. Maybe I have stared at this kind of video too long and there are just some features that drive me crazy. But I always try to be even handed with the NR and then balance that out with some sharpening all within the RemoveGrain effect. When I remove the effect though, there is very little difference that I can see related to sharpening per se. I confined the NR to the sky and green field. Makes me wonder if this is an artifact of the ProRes HQ codec.

I will remove all the effects from the comp and just try downscaling the original ProRes master to see if the NR is the source of my problem.

Thanks so much.

[jagabo]

Can you explain what you mean by way oversharpened?

Look at the light posts in the sky. Notice how there is a bright halo to the left and right of the dark posts. Or look at the people on the field. To the left and right of them there's a dark halo in the grass. The diagonal white lines on the field show aliasing. Those are all oversharpening artifacts. The oversharpening is only on the horizontal axis. The vertical axis looks ok. Hence the different rx and ry values in dehalo_alpha.

[SameSelf]

Look at the light posts in the sky. Notice how there is a bright halo to the left and right of the dark posts. Or look at the people on the field. To the left and right of them there's a dark halo in the grass. The diagonal white lines on the field show aliasing. Those are all oversharpening artifacts. The oversharpening is only on the horizontal axis. The vertical axis looks ok. Hence the different rx and ry values in dehalo_alpha.

If you are talking about the lossless intermediate, I am not sure if I see these halos. But I for sure see them in the downscaled video. But just in case the problem is my AE comp, here is the same clip with no effects. Do you see the same oversharpening? If so, then I have to reluctantly conclude my camera is the problem or the ProRes HQ codec on my Ninja. Thanks.