How do I change aspect ratio without re-encoding?

[Acehit]

All,

I am re-encoding some dvds, and as you know sometimes the aspect ratio on original dvds are not correct so I have made it my job to correct them. Currently I am using virtual dub to encode these movies, and at the best of times it takes 12 hours to encode a whole movie! Sometimes after that entire length I realise that the aspect ratio is a fraction off, and I have to encode it all over again which is taking up bags of computer time. I did some research and looked into MP4 box but I just cant understand how to use it.

Can anyone please give me a step by step guidance as to how I can re-encode video without going through this lengthy process?

My result files are mp4 format.

thanks in advance.

[LigH.de]

MP4Box will not re-encode anything. But it is a command-line tool with a quite complex syntax, it may be easier to use YAMB or the MeGUI (MP4 Multiplexer in the Tools menu) as user interfaces.

[Acehit]

I have loaded up Yamb, but there are no options to correct or set aspect ratio anywhere?

[ndjamena]

https://www.videohelp.com/tools/DVDPatcher
https://www.videohelp.com/tools/Restream

[PAL FS]
MP4Box -par 1="768:720" "%~1"

[PAL WS]
MP4Box -par 1="1024:720" "%~1"

[NTSC FS]
MP4Box -par 1="640:720" "%~1"

[NTSC WS]
MP4Box -par 1="2560:2160" "%~1"

-Edit- I think that's the NTSC Wide Screen ratio...

-Edit2- "%~1" is the file name by the way, I'm not sure how it works on a MAC.

[Baldrick]

I have loaded up Yamb, but there are no options to correct or set aspect ratio anywhere?

See https://forum.videohelp.com/threads/354080-Using-YAMB-to-change-aspect-ratio?p=2225013&...=1#post2225013

[kc1]

I use XMediaRecode for everything. Very easy to use.

[LigH.de]

XMedia Recode may be a bad idea; it will probably use ffmpeg or mencoder instead of MP4Box, therefore create an incomplete MP4 container. I am not even sure if it can remux without reencoding...

[enim]

How do I change aspect ratio without re-encoding?

OP needs to know container in details and patch the headers. Sometime it works & Sometimes it gets skewed.

[ndjamena]

There's a MAC version of MP4Box but as far as I'm aware, most header editors are Windows based. If you can get access to a PC/Laptop occasionally, editing the original DVD mpeg2 streams before you start encoding would be the best solution, yet somehow programmers with Mac and Linux machines haven't seemed to notice the problem.

[kc1]

XMediaRecode takes less than 6 hours to reencode a 3-hour movie. You can change aspect ratio. The quality is very good IMHO.

[LigH.de]

@ kc1:

The requirement here is not to recode. Your solution does not match the problem.

[kc1]

@ kc1:

The requirement here is not to recode. Your solution does not match the problem.

I understand, but 12 hours to reencode a movie is too much. XMediaRecode takes about fraction of it and changes aspect ratio at the same time.

[LigH.de]

Your argument is invalid: Remultiplexing with one flag patched takes only seconds, at most minutes (that's "a fraction of" hours), and does not decrease the quality because it preserves the content.

Furthermore, the speed of an encoder depends on the used CPU (your PC is not the same as someone else's PC) and settings (you can make the encoder spend more or less time trying to maintain quality). But we don't want to encode at all.

[ndjamena]

Why is the word 'wine' coming to my head?.. Oh, right, is that free?


-Edit- Wrong operating system:

http://gizmodo.com/5487242/how-to-run-windows-in-os-x-the-right-way

-Edit2- This one's a tad newer:

https://discussions.apple.com/docs/DOC-3321

[LigH.de]

I don't expect guides for a Macintosh to be relevant. The thread starter reported using VirtualDub, so he will probably run Windows.

[ndjamena]

Oh, sorry, wrong thread. One of these threads was about a MAC...

-Edit- Right, I'd been thinking of this thread https://forum.videohelp.com/threads/364807-Trouble-editing-mkv-around-keyframe

[roughedge]

Is there any programs you can do this to wmv files?

[ndjamena]

There WAS a program call MetadataEdit included with one of the Windows SDKs that could edit a wmv header. I've downloaded the current Windows SDK for Visual Studio 2012 and I can't find any useful examples at all. MetadataEdit looks to be another one of those very useful examples that has completely disappeared. Unless I'm just not looking in the right spot.

[Cornucopia]

You need WMFSDK11. It has MetadataEdit.exe (at least acc'd to Doom9).

Scott

[El Heggunte]

Cornucopia is right, Windows Media Format 11 (part of the WMP 11 setup) includes that "thing"

And B4U ask --- no, I have no interest in learning how to use it.

[ndjamena]

Microsoft seems to have collapsed everything into the Windows SDK at this point, every link I can find seems to take me there.

-Edit- XP only