Resolution, Bitrate and Quality

[JonNorway]

Hi.
I am new and I hope someone can help me to clarify what is gives the best quality when considering Resolution and bitrate.

I have a mpeg video which I would like to convert to aspect 16:9 to run on my computer which are more pleasing to the eye.
Using Movavi video converter I convert from mpeg to mpeg with FrameSize=Smartfit, ResizeQuality=Good BitRateType=Auto.

Original video 720x480 gives BitRateMode=Variable and BitRate=4963Kbps and MaximumBitRate=8000Kbps.
1. Convert to 1280x720 gives BitRateMode=Variable and BitRate=7166Kbps.
2. Convert to 960x540 gives BitRateMode=Variable and BitRate=4502Kbps.
3. Convert to 854x480 gives BitRateMode=Variable and BitRate=3983Kbps.
4. Convert to 854x480 gives BitRateMode=Variable and BitRate=11.8Mbps Using BitRateType=VBR.

What I have understood from reading in forums is that the best result would be number 3 and 4 (854x480) which are closest to the original video in size.
But when I try to look at the videos I find number 1 (1280x720) more pleasing with shadows (contrast).

Could video number 1 actually look better or am I daydreaming?
Could it be that some places are good and some are not so good?

Thanks.
Jon.

[Bernix]

IMHO Have you try to set aspect ratio to 16/9 and watched the original file ? You can do a lot of settings in your player. And do not need to reencode each video to 16/9
And yes, it is possible that 1280x720 looks better. It depends what algorythm was used for resizing.

[JonNorway]

IMHO Have you try to set aspect ratio to 16/9 and watched the original file ? You can do a lot of settings in your player. And do not need to reencode each video to 16/9
And yes, it is possible that 1280x720 looks better. It depends what algorythm was used for resizing.

Thanks Bernix, good Points.
I did not even know that it was possible to do anything with the player so I have had a look now.

I am using Powerdvd 15 as a player and they do not recommend it:

Apply stretch: select this option to stretch all parts of the video equally, resulting in noticeable distortion when the aspect ratio of the video display does not match the aspect ratio of the monitor.

Thanks for your kind information.
Jon.

[hello_hello]

The PowerDVD "apply stretch" function you quoted seems to be for stretching the video to match the aspect ratio of the display. Stretching the video that way isn't recommended as it'll distort the video, unless it's supposed to display with the same aspect ratio as the display. Then it's a good thing.

NTSC DVDs (or mpeg video) are either 4:3 or 16:9. They're always 720x480 which is neither 4:3 or 16:9, so they have to be squished or stretched to display correctly (ie 640x480 for 4:3 or 854x480 for 16:9).
If they're 4:3 and they're stretched to fill a 16:9 display, they're not being resized to their correct display aspect ratio, which isn't recommended. If they're 16:9, stretching to fill a 16:9 display is desirable, as that's how they're supposed to display.

When you resize an NTSC DVD to 832x468 or 854x480 or 960x540 etc for encoding, you're resizing to the correct 16:9 aspect ratio and encoding that way. It's technically better just to re-encode the original video at 720x480 and let the player resize it to 16:9 on playback, just as it would for the original video, assuming the player does it correctly.

When the original 720x480 video is being resized to fill a 1080p display (for example) it's being resized once. From 720x480, upscaled to 1920x1080.
When you resize before encoding (854x480 or 1280x720 etc) it's being resized twice. Once before encoding, and then again to be upscaled to 1080p.
Each resizing would likely be different as there's all sorts of different resizing methods, some quite sharp, some not very sharp, and it could be the video encoder's resizing and the video player's upscaling combine to produce a more pleasing result. It could be when you resize to 720p for encoding the resizing is a bit sharper than the player's upscaling to 720p, so the version encoded at 720p might look better in that case.

The rule of thumb for encoding tends to be to avoid any resizing if possible (if your player/TV displays the encoded 720x480 video correctly, that's technically the best) and if you resize, it's preferable not to resize the height. Just resize the width to the correct aspect ratio. 640x480 for 4:3, 854x480 for 16:9. Having said that, it's your video. Do what you prefer. I do.

I'm not familiar with Movavi video converter.Which encoder does it use for encoding? There's probably free DVD ripping and conversion programs that'd do a better job, or at least give you more control.

[_Al_]

Let someone shuffle those videos so you have no idea what you are actually watching, evaluate it again, and then report back with result.

[hello_hello]

It definitely does make a difference, probably more so for PAL DVDs as when resizing to square pixels there's more resizing involved than for NTSC DVDs, but sharpish resizing to square pixels makes a difference.

Pic 1 is an 720x576 anamorphic encode, pic 2 was resized with Spline36Resize to 1024x576 for encoding. Both upscaled to 1080p by MPC-HC.

1. Anamorphic:


2. 1024x576:


Not that I'm necessarily saying it's always good. The above was MPC-HC upscaling with Bilinear resizing. Below are the same two frames with MPC-HC using Bicubic resizing for up-scaling (sharper upscaling).

3. Anamorphic:


4. 1024x576:


By the fourth screenshot we're heading into over-sharpened territory, and by doing nothing else other than resizing to 1024x576 for encoding, then upscaling to 1080p for viewing.

You'd probably need to open each image full size in it's own tab and switch between them to tell the difference.

I tend to go with method 2 myself as that's how I'd be watching the encoded video most of the time, and because the media players built into the TVs here don't support anamorphic MKVs/MP4s. That video's a bit noisy so I'd noise filter it which would take the edge off a bit when using a player with sharp upscaling, but still, resizing when encoding can make quite a difference, depending how sharp it is and how much upscaling happens on playback etc.

[JonNorway]

Thank you so much hello_hello, you're a master - now everything makes sense to me.
I have a lot of DVDs on my hard disk both NTSC from US and PAL from Europe.

When I analyzed my last DVD I found 4 MPEG2:
Movie 1&2 720x480 with 16:9
Movie 3 720x480 with 4:3
Movie 4 720x480 with 2.40:1
So just as you said movie 1&2 plays perfectly in the player.
Movie 3 and 4 are not perfect in the player and needs to change the aspect ratio to 16:9.
And you have confirmed to me the rule of thumb should be not to resize the height giving 854x480 as the best solution for 16:9.

Movavi Video Converter has many settings like:
- Letter box, stretch, crop, auto.
- Two pass encoding.
- Interpolation Low (Draft), Bilinear (Good, Medium) and Bicubic (Slow).
I have not used the software much until now, but I have become more and more impressed by it.

I tend to go with method 2 myself as that's how I'd be watching the encoded video most of the time, and because the media players built into the TVs here don't support anamorphic MKVs/MP4s. That video's a bit noisy so I'd noise filter it which would take the edge off a bit when using a player with sharp upscaling, but still, resizing when encoding can make quite a difference, depending how sharp it is and how much upscaling happens on playback etc.

Very good points you made here - I will need some time to reflect on it and have a more close look at your photos.

Thanks hello_hello, for your kind information and good explanation.
Also to you _Al_ for your suggestion.
Jon.

[jagabo]

Movie 1&2 720x480 with 16:9
Movie 3 720x480 with 4:3
Movie 4 720x480 with 2.40:1

So just as you said movie 1&2 plays perfectly in the player.
Movie 3 and 4 are not perfect in the player and needs to change the aspect ratio to 16:9.

Movie 3 is probably playing properly in the player: a 4:3 picture pillarboxed on the 16:9 screen. That's the way it's supposed to be displayed. Playing it any other way will result in distortion or picture loss.

Regarding movie 4, DVDs don't come in 2.40:1, only 4:3 and 16:9. A 2.4:1 movie will be letterboxed in a 16:9 or 4:3 DVD. You're player is probably playing that the way it is supposed to too. If it's a 16:9 DVD the picture should fill the 16:9 screen horizontally but have letterbox bars top and bottom. If it's a 4:3 DVD you will have a small 2:4.1 picture in the middle of the screen with both letterbox and pillarbox bars all around.

[hello_hello]

Thank you so much hello_hello, you're a master - now everything makes sense to me.
I have a lot of DVDs on my hard disk both NTSC from US and PAL from Europe.

When I analyzed my last DVD I found 4 MPEG2:
Movie 1&2 720x480 with 16:9
Movie 3 720x480 with 4:3
Movie 4 720x480 with 2.40:1
So just as you said movie 1&2 plays perfectly in the player.
Movie 3 and 4 are not perfect in the player and needs to change the aspect ratio to 16:9.
And you have confirmed to me the rule of thumb should be not to resize the height giving 854x480 as the best solution for 16:9.

How are you analysing the DVD?
It's not uncommon for a conversion program to get the aspect ratio wrong, and 2.40:1 isn't even a DVD complaint aspect ratio. It's 16:9 or 4:3. That's it.
The only way to put a 2.40:1 aspect ratio video onto DVD is to add black bars top and bottom to make it 16:9. The black bars are often cropped before encoding, which gives you a 2.40:1 output, but the DVD video itself can't be 2.40:1.

If the conversion program is getting the aspect ratio wrong, Ideally there'd be a way to correct that before it's encoded so it's resized and encoded correctly.

Movavi Video Converter has many settings like:
- Letter box, stretch, crop, auto.
- Two pass encoding.
- Interpolation Low (Draft), Bilinear (Good, Medium) and Bicubic (Slow).
I have not used the software much until now, but I have become more and more impressed by it.

Letter box and crop would relate to the black bars. Whether to add them or remove them as appropriate. Stretching is something you'd almost never want to do.
Does the program tell you which encoder it's using for 2 pass encoding?
Interpolation = the resizing method. Low (could be anything), Bilinear (the upscaling method I used for the first two screenshots) and Bicubic (the sharper upscaling method I used for the second two screenshots).

For the two pics where I resized the video to 1024x576 before upscaling I used a different resizer again, but it's similar to Bicubic in sharpness.

Very good points you made here - I will need some time to reflect on it and have a more close look at your photos.

Pic 1 & 3 = encode the video "as-is" (720x480), no resizing, then upscale to correct resolution and aspect ratio on playback. It's probably the best method as most players have pretty good upscaling these days. Pic 3 was encoded that way and upscaled with sharper resizing.
I don't know if the program you're using supports that method and not all hardware players will resize that sort of video correctly.

Pic 2 & 4 = resize to 854x480 (16:9 NTSC) for encoding, then upscale as required on playback.

Either way though, if you watch the video on a 1080p display, you're somewhat at the mercy of the player's upscaling as you generally have no control. If you don't resize or you resize to 854x480 with a soft resizer, and the player uses soft upscaling, you can end up with a more blurry result (pic 1). On the other extreme, if you use sharp resizing to 854x480 and the player uses sharp upscaling, sometimes the end result can look too "sharpened". Mostly I find it looks okay and I don't like "sharpened" video myself, but there's a potential for it to end up looking too sharpened.

By the way, the encoding program's "crop" function should be designed to remove any crud or black around the picture. A 2.40:1 picture on DVD (for example) will have quite a bit of black top and bottom. Something like 124 pixels worth in total. When it's removed, you're left with something like 720x356 worth of picture. You could encode it "as-is" at 720x356 or resize to 854x356 and encode that way (same principle as for 720x480 or 854x480). 720x356 or 854x356 would be fine as some of the height was removed, but it hasn't been resized.

On playback, when viewing the video on a 16:9 display, the player should add the black bars back top and bottom for a total of 16:9 again. The height of the picture isn't supposed to match the height of the screen in that case because the picture itself is 2.40:1, not 16:9. I'm just explaining all that in case you think the encoded video should always fill the screen. Often it won't. It just needs to display "correctly".

[hello_hello]

The pics above were taken from some samples I had sitting on my hard drive, but they made me curious as to how that video looked after I actually encoded it for myself (the difference would probably have been some extra filtering, mainly noise removal), so I dug out the encode. It's about three years old. I'm not posting these for any particular reason other than I was curious enough to look.

It turns out I cropped and resized to 1020x556. I don't know exactly what else I might have done. It was too long ago.

MPC-HC upscaling to 1080p, Bilinear resizing (how I'd normally watch it):


MPC-HC upscaling to 1080p, Bicubic resizing (probably closer to how my TV's media player would upscale):


Mind you in the end none of it's worth getting too excited about. They all look like crap compared to decent quality 720p/1080p.

[JonNorway]

Thanks jagabo, for your kind comment.

Movie 3 is probably playing properly in the player: a 4:3 picture pillarboxed on the 16:9 screen. That's the way it's supposed to be displayed. Playing it any other way will result in distortion or picture loss.

OK, I understand, but I thought that it is acceptable to convert 4:3 to 16:9 or the other way around as long as I keep the frame proportions. Using Letterbox/Smartfit (no stretch or crop) might distort/picture-loss the video as you say, but I thought it is so little that the human eye will not recognize it. In this thread I have been told that the rule of thumb should be not to resize height when converting from 4:3 to 16:9 giving 854x480 as the best solution from 720x480.
However I could see that in this special case the aspect ratio 4:3 have been made wrong from the publisher(National Geographic) with black bars all around, so after I cropped it to 720x404 it appears to be correct.

Regarding movie 4, DVDs don't come in 2.40:1, only 4:3 and 16:9. A 2.4:1 movie will be letterboxed in a 16:9 or 4:3 DVD. You're player is probably playing that the way it is supposed to too. If it's a 16:9 DVD the picture should fill the 16:9 screen horizontally but have letterbox bars top and bottom. If it's a 4:3 DVD you will have a small 2:4.1 picture in the middle of the screen with both letterbox and pillarbox bars all around.

Very good jagabo, I am so happy that you and hello_hello have pointed this out to me.
When I analyzed, I found that the IFO was set to 16:9 and VOB set to 2.4:1 (I don't understand why they have aspect ratio on 2 different places).
So the Movavi converter ignored the IFO and just copied the VOB with 2.4:1 to a plain MPG (looks like a bug to me).
Then the player displayed it as 2.4:1 (which is the same as 21.6:9).

Thanks hello_hello, for your kind comment.
I am using MEDIAINFO to analyze any media file by right click in windows explorer.

If the conversion program is getting the aspect ratio wrong, Ideally there'd be a way to correct that before it's encoded so it's resized and encoded correctly.

I was actually surprised that the conversion program got the aspect wrong, but as you said I can override the default as long I am aware of it. Looks like it is not uncommon to have conflicts between IFO and VOB.

I do not know which Two-Pass encoding is being used, but I assume it uses the same encoding as the One-Pass depending whether you specify Draft(nearest-neighbor), Good and High(Bilinear) or Best(Bicubic). Looks like Two-Pass can only be set when I convert to another file type.

Good you mention about stretch and crop. After reading I have understood that it should only be used when you have a video that has been converted with wrong aspect ratio in the first place and needs to be corrected. Normally I should only use Letterbox/Smartfit. Now that you and jagabo have explained what is needed to know about black bars, it will be much easier for me to recognize wrong aspects in future.

Either way though, if you watch the video on a 1080p display, you're somewhat at the mercy of the player's upscaling as you generally have no control. If you don't resize or you resize to 854x480 with a soft resizer, and the player uses soft upscaling, you can end up with a more blurry result (pic 1). On the other extreme, if you use sharp resizing to 854x480 and the player uses sharp upscaling, sometimes the end result can look too "sharpened". Mostly I find it looks okay and I don't like "sharpened" video myself, but there's a potential for it to end up looking too sharpened.

This is exactly what I have been looking for. I have used FastStone Image Viewer and compared your photos. So in special cases a 'sharpened' video can have all the good qualities and at the same time being too sharp for the human eye. Brilliant hello_hello. For me, many things to consider and a lot to learn.

Thanks jagabo and hello_hello, for your kind information and good explanation.
Jon.

[jagabo]

I thought that it is acceptable to convert 4:3 to 16:9 or the other way around as long as I keep the frame proportions... I thought it is so little that the human eye will not recognize it.

Of course, you'll have to decide what's acceptable to you. But 4:3 stretched to 16:9 is very obvious. Cropped to 16:9 will usually be less obvious but you will lose some sharpness and sometimes miss important picture elements (you're discarding 1/4 of the picture). It's better to just accept letterbox or pillarbox bars on your TV knowing they are there to keep the original material intact.

[JonNorway]

OK, this thread have been a learning curve for me and I still have a lot more to learn.
I would like to sum up what I learned so far and believe what is important:

1. Many DVD from the shop can come with the wrong aspect ratio and we have to either crop (remove black bars), convert or change the aspect ratio directly in the file (DVDPatcher) when necessary. Stretching deliberately done breaking the original aspect ratio is likely to never happen with DVD from a shop.
2. If there are conflicts in aspect ratio between IFO and VOB, we must make sure the converter software does this correctly.
   Normally the IFO will be correct.
3. If we need to convert, the rule of thumb should be to keep the same height as the original.
4. Quality can be many things and the original and advanced conversion does not always reflect what is best to the human eye.
5. There are several opinions whether we should convert the original video or not.
   Some say that we should accept what the original presents to us since the original will not distort the video.
   Others like myself will not hesitate to convert a 4:3 to 16:9 if the video has a good quality since it for me appears more pleasing on the computer screen.
6. Bitrate needs to increase more to keep up the quality if we were to convert say from 720x480 to 1280x720. Then, 854x480 might give us a better solution although there might be exceptions.
7. 720x480 (NTSC 3:2) and 720x576 (PAL 5:4) are stored as Non-square pixels and it is the PAR (Pixel Aspect Ratio) which tell the graphic card and/or player how to display them on the computer screen with either 4:3 (fullscreen) or 16:9 (widescreen).
   An example of Square pixels would be 1280x720 (16:9).
   DAR (Display Aspect Ratio) = PAR (Pixel Aspect Ratio) * SAR (Storage Aspect Ratio) is the formula used by the graphic card and/or the player.
   Some online sites require that we convert to square pixels (DAR=SAR).

Thanks to all who has helped me both with solution and understanding.
Jon.