aspect ratio of AVI video file incorrect

[pglenn]

I have an AVI file that has a resolution of 512x272, but when it is played by gbpvr it is displayed full screen. How can I get gbpvr to display the video correctly?

currently using
- nvidia video decoder
- anamorphic/raw aspect (I also tried content default)

Patrick

[nemulate]

Have you tried pressing F7 to change the aspect ratio?

[pglenn]

AHH, I am a new-comer (obviously), I was unaware of the F7 option, I will try that when I get home.

is there a way, for the aspect ration to be auto-selected? I would prefer for the program to automatically set it based on the video unless I set one specifically...

Patrick

[LilY0da]

No there isn't, since aspect ratio detection is a very un-scientific process
If you have a Linux server, or know how to re-code Linux PHP into Windows PHP, take a look at the "Has anyone tried Avisynth" thread. There's a PHP script posted there that *tries* to detect what is the current AR of a video, and how to crop/add borders to make it a 4/3rd image.

[pglenn]

well, what is happening with other programs (MediaPlayerClassic, PowerDVD, ATI video player, WindowsMediaPlayer, etc) that open full-screen with the video displayed in perfect aspect ration with black borders as needed? arent they auto-detecting and adjusting the borders accordingly?

Patrick

[LilY0da]

They aren't detecting anything. They are either:
considering that the video file has a pixel AR of 1:1, then adding borders to make the file 4:3
stretching the file to your window borders directly

I can't count how many times I've had to resize my window in mediaplayer (classic or not) to get a correct display.

[pglenn]

I normally use Media Player Classic in full-screen mode. Whatever the method it actually uses, MPC always plays the files in the correct A/R with appropriate borders top/bottom and/or left/right without me having to make any adjustments. It does "stretch" the video to fit the screen but leaves it in correct aspect. Not intending any arguments at all. Just would be nice if GB-PVR could do the same.

Patrick

[LilY0da]

OK, so try this:
- record a show in 352x480
- convert it to XviD
- play it in MPC

If your MPC is configured as you say (keep pixel AR and add borders) it won't change the AR of your video, and it will be stretched up, with big borders on the sides.

There are 2 main ways to encode videos.
1) assume the content of your video file it will be stretched to a 4:3 or 16:9 display without adding borders/cropping. If you watch the file without stretching using the normal video resolution, it looks distorted. Exemples are SVCDs who encode a 4:3 image in a 480x480 stream, or anamorphic DVDs who encode a Widescreen image in a 720x480 stream.

2) encode your file with a 1:1 pixel AR. Your file plays fine on a PC in a window, but if the file doesn't have a AR of 4:3, you'd need to add borders to play it full screen, since it can't be stretched.

If MPC plays all your files with the correct AR without you having to change its settings, it's that all your files were encoded with the same logic. Consider yourself extremely lucky...

There are headers in MPEG2 files to specify the AR, but as far as I know, not in AVI files.