Hi fellow transcoders,
I use Mediacoder to convert MPG- and DVD-files to xvid. Maybe 3 out of 4 movies transcode well, but sometimes the aspect ratio changes unexpected, and pictures are stretched. To see the squeezed video and the original you may want to look at http://dakapo.homelinux.net/ratio.png (warning, huge pic, you better have broadband). To the left you see the original mpg, shown in Nero Showtime, to the right the resulting avi, shown in PowerDVD.
As you can see, the vertical resolution stays the same, while the horizontal resolution is minimized and the picture is squeezed. In the lower left of the screenshot you see mediacoder's settings on the picture tab: no resize, no crop, no apext ratio.
So, why does Mediacoder changes the aspect - but only sometimes?
The funny (wierd?) thing is: Some day I recognized that, according to Gspot, the original and transcoded videos have the same resolution (720x576), thus the same aspect ratio! After some gambling I found out, that it is just PowerDVD, which shows the squeezed picture (and MS Mediaplayer, and probably every other programm which uses Windows' standard-codecs). If I view the resulting AVI in Nero Showtime (which uses own/nero-proprietary codecs), the aspect ratio is perfect!
The sad thing is: The handling of Nero is not mine, I want to view my videos with PowerDVD. So, why does PowerDVD shows some transcoded videos with a wrong aspect ratio?
So these are my questions: Can I repair the transcoded avi? Can I prevent it from beeing squeezed in PowerDVD by some other setting in mediacoder? Any idea, hint, RTFA?
TIA,
aposch
Aspect Ratio crazyness - sometimes
Moderator: HuggiL
Sometimes it might be possible to modify the aspect ratio without reencoding. Could you cut say 3 seconds worth of the vid and upload it somewhere where we can download it and do some tests?
I'm no an expert in this field, but anamorphic videos are videos where they are stored at 4:3 ratios but are stretched to 16:9 or 2.33 upon playback. Perhaps the movies which you had problems with are anamorphic movies.
Also, as BlinkN wrote, cropping out the black bars is fairly important. They are unnecessary because proper movie players will fill in the black zones automatically and that leaving them there will hurt the compressability of the video. It takes more bits to preserve the sharpness of the black bars.
I'm no an expert in this field, but anamorphic videos are videos where they are stored at 4:3 ratios but are stretched to 16:9 or 2.33 upon playback. Perhaps the movies which you had problems with are anamorphic movies.
Also, as BlinkN wrote, cropping out the black bars is fairly important. They are unnecessary because proper movie players will fill in the black zones automatically and that leaving them there will hurt the compressability of the video. It takes more bits to preserve the sharpness of the black bars.