Aspect ratio problem

[deltat]

Hi all,
We captured some video clips for testing via pinnacle's 510-USB, the details of the videos are listed below.

Video
Format : MPEG-4 Visual
Format settings, BVOP : No
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default
Codec ID : DX50
Codec ID/Hint : DivX 5
Duration : 19s 19ms
Bit rate : 4 327 Kbps
Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 1.500
Frame rate : 29.970 fps
Standard : NTSC
Resolution : 24 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.418
Stream size : 9.81 MiB (95%)
Title : Video
Writing library : DivX 6.6.1.4

http://forum.doom9.org/attachment.php?attachmentid=11595&stc=1&d=1284968877


The problem is when play back the videos via a digital player,

Player setting:
Aspect ratio: Letter Box 4:3
Video system: NTSC

There are black bars both on the top and bottom of the screen.
http://forum.doom9.org/attachment.php?attachmentid=11596&stc=1&d=1284968885


If the aspect ratio in the player is set as below:

Player setting:
Aspect ratio: 16:9
Video system: NTSC

There are black bars on the left and right side.
http://forum.doom9.org/attachment.php?attachmentid=11597&stc=1&d=1284968897



And if

Player setting:
Aspect ratio: Pan and scan 4:3
Video system: NTSC

The image is cropped.
http://forum.doom9.org/attachment.php?attachmentid=11598&stc=1&d=1284968907

Are there any solutions that the video can be played without content loss and no black bars for a NTSC system?

Thank you.

[Ghitulescu]

How does the video look like on a TV?

[TheSkiller]

Well, if it's a DivX then you have to set the PAR or DAR correctly.

Display aspect ratio : 1.500

This is wrong. It has to be set to 15:11 (1.36:1) for a 720x480 video (if it's a 4:3 video).
Your player does exactly what it is told.

[Ghitulescu]

Is the first image the intended AR?

Which player did you use to play the files?

Are you sure the borders come from the video and not from the displaying window (try enlarging, minimizing the player)?

[deltat]

Well, if it's a DivX then you have to set the PAR or DAR correctly.

This is wrong. It has to be set to 15:11 (1.36:1) for a 720x480 video (if it's a 4:3 video).
Your player does exactly what it is told.

Thanks.
Do you know how to change the aspect ratio without transcoding, because we don't want to affect the image quality in transcoding.

I tried to change the aspect ratio with following command line
ffmepg -i input.avi -aspect 4:3 -vcodec copy output.avi


but it doesn't work. The aspect ratio is still 3:2.

[deltat]

Is the first image the intended AR?

Which player did you use to play the files?

Are you sure the borders come from the video and not from the displaying window (try enlarging, minimizing the player)?

Thanks for your reply.

The first image is extracted from the video captured by the capture card.

The video player is a hardware player, and is attached to a NTSC TV system via CVBS.

[Ghitulescu]

On my PC monitor the third image is like it should be. However, the PAR is 1:1 for a PC and if the image posted is photographed (which I don't believe, as it's 720x480, it can't be just pure chance here) then I would say let the settings as they are (3rd ones).

As for the first image: it should be displayed perfectly on a TV (the NTSC pixels are "high").

[GodofaGap]

Are there any solutions that the video can be played without content loss and no black bars for a NTSC system?
If you have a 16:9 screen and this is 4:3 content, not really, unless you want to accept one of those horrible stretch modes (but they usually crop as well).

I think you first need to figure out what you are actually configuring with the aspect ratio setting of the player.

To me its also the pillar boxed image that looks right, but it being 720x480 doesn't make any kind of sense... how did you get those?

[TheSkiller]

You can change PAR and DAR with MPEG4 Modifier (http://www.moitah.net/).
But, there is a chance that your player ignores these flags and always assumes your video is square pixel.
To my eyes the first image (this is the raw image, right?) resized to square pixels (656x480) looks correct. If this was captured from a NTSC source and not weirdly cropped and resized back to 720x480 afterwards then everything should be ok.

[deltat]

You can change PAR and DAR with MPEG4 Modifier (http://www.moitah.net/).
But, there is a chance that your player ignores these flags and always assumes your video is square pixel.
To my eyes the first image (this is the raw image, right?) resized to square pixels (656x480) looks correct. If this was captured from a NTSC source and not weirdly cropped and resized back to 720x480 afterwards then everything should be ok.

Thanks. It works as what I expected after changing the DAR with MPEG4 Modifier.

[henryho_hk]

Your source appears to be legacy NTSC 4:3 and so the pixel aspect ratio (PAR ... or pixel shape) is 10/11 (or 38800/42651), i.e., the frame aspect ratio (FAR) or display aspect ratio (DAR) is (720/480)*(10/11)=15/11. Since legacy NTSC is meant to show the inner 704 pixels only, it's therefore (15/11)*(704/720) = 4/3.

If your DivX player can handle PAR embedded in AVI, simply specify "NTSC 4:3" when encoding, or change it using MPEG4Modifier when after encoding.

If it can't, resize your footage to 656x480, or crop away 16 horizontal pixels and resize to 640x480, and then encode as 1:1.