PSP MP4 editing / changing values

[iThinkYouBrokeIt]

I have a PSP-MP4 video that is only able to be viewed in 16:9 mode. The problem is, the source material was obviously 4:3, so the image is stretched.

Is there a program that i could use to fix this problem without re-encoding? I know how to do this with MPEG-2, but I've never had to it with MP4...

[guns1inger]

Probably not. Generally, PC based files have a 1:1 pixel aspect ratio and no DAR (although it is possible to store one, nothing really uses it). The main exception to this is DV-AVI, where some editors will observe the 16:9 flag if set.

I suspect you will have to reseize the video to the correct aspect ratio and rencode. This will let the playback device display it correctly and add whaever bars are necessary.

[iThinkYouBrokeIt]

Well, this isnt really a PC based file, as its formatted for playback on my PSP. Normally, while playing the file, i can change the view mode, which involves changing between 1:1, 16:9 and 4:3 - zoomed, or cropped.

The problem is, with this video, it is locked so that the aspect ratio can not be changed to 4:3 because it was incorrectly given the 16:9 flag. I would like to remove it and change it to either 4:3 or 1:1.

[guns1inger]

Hopefully this will help

https://forum.videohelp.com/viewtopic.php?t=285971&highlight=mp4+aspect+ratio

It refers to Mac software in this instance, but I suspect the underlying issue is the same.

[celtic_druid]

mp4box/yamb from recollection can change the PAR. Sounds like maybe it wouldn't make any difference though.