Selur's Little Message Board

Hi

thank you for the advice, i'll check the result next times !  

but for the video we speak about (result of step 2. with a "corrected" PAR), its look is ok, rounds are round.

so, do i have to set 'Input PAR : 8x9' also when i use it as a source in a new task/job ?

EDIT :
i compared the video between VLC & avidemux and the result is strange :
with VLC the video looks good but not with avidemux  
how do you explain that ?
what should i do to have a corrected video with a good look in every player ?

the screenshots are here

regards

Avidemux ignores the PAR during preview. Normal Mediaplayer don't.
If you want to see the same in Avidemux as in VLC you need to tell Hybrid to convert to PAR 1:1.
To do this:

1. enable "Crop/Resize->Pixel Aspect Ration (PAR)->Convert output to PAR"
   
2. set "Crop/Resize->Pixel Aspect Ration (PAR)->Convert output to PAR" to "Square Pixel (1:1)"
   

Cu Selur

Yes !
I think it'll be better to convert so the information will be stored in the video - non ?
do i need to encode to do so or can i use 'video -> passthrough' ?

regards

Adjusting from one PAR to another without causing distortions requires resizing which requires reencoding.
Personally I wouldn't change the PAR to 1:1, like I wrote any media player should properly read the PAR info and respect it.

Cu Selur

Hi

i tried this method (modify PAR during step 1 'encoding' + cut according chapters in step 2) & it didn't change the result : the 1st chapter had the WB logo not round  

i tried to modify the step 2 setting 'muxing->PAR 8x9' (and not 1x1), and then the WB logo was round...

very strange...
that would mean that whatever we set in step 1, if we use a step 2, we have to set PAR with the same setting...
no ?

Not totally sure what you do in what order.
-> write down what you do, step-by-step, create a two debug outputs, one for the encoding part and one for the splitting part.

If you want the output to be 1:1, you have to:

• overwrite "Crop/Resize->Pixel Aspect Ration (PAR)->Input PAR" to your liking (in example 8:9)
  
• enable "Crop/Resize->Pixel Aspect Ration (PAR)->Convert output to PAR"
  
• set "Crop/Resize->Pixel Aspect Ration (PAR)->Convert output to PAR" to "Square Pixel (1:1)"
  

during the encoding step.

During the splitting "Crop/Resize->Pixel Aspect Ration (PAR)->Convert output to PAR" should be disabled and if you load the (new) source input should be detected with a PAR of 1.

Cu Selur

Hi,

it seems ok with this method !

BTW : during splitting, as i choose "video-> passthrough', "Crop/Resize->Pixel Aspect Ration (PAR)->Convert output to PAR" is indeed disabled, and the (new) source input is detected with a PAR of 1


regards

Hi

i'd like to precise smthg, because it doesn't work anymore...

Full Context :
i have a 720x480 source with PAR = 1 - but where the circles are flattened (using VLC), so this forum told me toi modify it, setting 'input PAR : 8x9'.
the result video has a PAR stated by Hybrid as 0.889 - but with VLC, a circle is not distorted (strange, no ?)

I have to crop this video :
- 26 left
- 4 bottom
so the result will be 696x476
ok ?

1/if i set 'input  PAR :8x9' and 'convert output to PAR : square pixel' alone, the result is that the circles are flattened again



2/so i also have to set 'target resolution : 696x476'

do smone understand why it is so ? is it normal ?
does the "visual" problem come from VLC ?

regards

Quote:I have to crop this video :
- 26 left
- 4 bottom
so the result will be 696x476

Yes, if no PAR conversion would take place

I try to repeat this as I understood your post.

a. you have a 720x480 source with a wrong PAR
b. when you change the PAR to 8x9 the output is played properly inside VLC
c. when you crop the source to 696x476 and also enable 'convert output to PAR' and set that to 'square pixel' the output is distorted again.
Enabling the conversion from PAR 8:9 to PAR 1:1 should automatically enable resize and adjust the height, so the output should be 694x536.
If you manually do additional resizing and disable the 'Auto adjust' in the resizing, you yourself are responsible for keeping the aspect ratio properly,.. so don't blame Hybrid.

Quote:so i also have to set 'target resolution : 696x476'

What is forcing you to do that? If you do that with the PAR-conversion enabled you will get a distorted output.

Quote:do smone understand why it is so ? is it normal

It is normal that if you blindly resize your output is distorted.

Quote:does the "visual" problem come from VLC ?

not unless you overwrite the PAR in VLC,...

Cu Selur

Hi,

I don't think i blamed Hybrid, did i ? if so, excuse-me, it was not my intention, i'm just trying to understand how all this works & so i ask (too many ?) questions...
So I re-read https://en.wikipedia.org/wiki/Pixel_aspect_ratio many times to try to understand how it works.

assuming SAR × PAR = DAR.

if i understand well :
- my 720x480 source comes from a NTSC LD source & has a PAR=1 (analysed by Hybrid) ; if a circle is flat, it's because of the SAR=720:480=3:2 ? it should be 640x480 with a SAR=4:3 ?
- assuming that, what can i do in Hybrid to correct that ?

-->i see 2 ways :
1/ modify the resolution (= SAR) setting "crop/resize->base->picture resize->target resolution=640x480"
2/ modify the PAR = DAR/SAR = (4:3)/(3:2)=8/9=8:9 ie. 0,889
ok ?

1/it works if "crop/resize->base->picture resize->auto adjust" is disabled ; i didn't see this parameter at 1st, so i had as a result a 640x428 video with a PAR = 1, and i thought it didn't work...
2/so the forum told me to use the 2nd solution "crop/resize->base->Pixel Aspect Ratio->input PAR = 8x9" - which worked, and the result is a 720x480 video with a PAR=0,889 (NOTA : with this solution we don't need to encode, so it's quicker !)

Let's suppose i take now the 720x480 video with a PAR=0,889 as source.
I have to crop this video (left=26 & bottom=4)

the only thing i see to do is to set the 2 crop parameters + set the input PAR during an encoding task, right ?
that means :
- "crop/resize->base->picture crop->left=26 & bottom=4"
- "crop/resize->base->Pixel Aspect Ratio->input PAR = 8x9" -> in fact, "input PAR" should already be set by Hybrid...

--> so the result should be 696x476 with a PAR=0,889, right ?
I will try this ASAP again

My understanding is that it isn't a problem to have a video with a PAR <> 1 ?
won't it be a problem if i split this video in multiple videos ?

regards