Placing Video in MP4 Format or Compressing in h264 Cuts Its Length? Huh?

[kalorx]

Hi all. I recently backed up a DVD of mine to h264. I set a AVS script to use the decomb filter with the purpose of teleciding and decimating it to deinterlace and down the framerate to 23.976.

In the Virtualdub output preview the length was correct: 00:57:07. Also, everything was perfect, from smoothness to what have you. So I ran the script through x264 CLI v292 (via MeGUI x264 0.2.2.3) and ended up with a video that was only 00:54:47!

However, since the first and last frames were as they should've been, I surmised that some sort of algorithm cut certain frames out. It couldn't have been Decomb's Decimate() function, because things were perfect in the VDub output preview!

Then again, it may not have been the x264/MeGUI compression that did this. I compressed to raw video -- something I can't view (or don't know how to view). Only when I placed it in the MP4 container could I view its contents. Maybe it was MP4Box 1.3.1 that did this? I doubt it. It makes much less sense.

I'm thoroughly confused. Any help would be greatly appreciated.

EDIT: Even the preview in MeGUI is 00:57:07. Now I'm REALLY dumbfounded! How can the simple act of compression kill 2.5 minutes of time?

Thanks,

Robert Aronson
http://www.progressivedementia.net

[foxyshadis]

.264 -> .mp4 defaults to 25 fps. Your input was most likely 23.976. If you do the math, you'll likely find the ratio is the same as the time difference. ;) Use the -fps parameter in mp4box to change the framerate back to normal.

This is caused by a missing feature in GPAC, it doesn't read h.264 raw framerates.

[kalorx]

Okay... so where do I put the -fps parameter? Everytime I add to the command line (no matter where), I always get an error message.

EDIT: Oh, wait... duh... I wasn't entering a FPS value...
EDIT: Should I enter 23.976 or 23976?

[foxyshadis]

-fps 23.976 (you might want to check your avs output in vdub's info just to make sure first.)

[kalorx]

Yeah, the output is 23.976.

...and it worked! Thanks very much! Finally... my days of using completely obsolete ripping and compression methods are over. Mmmm... progress...