ExifTool Forum

General => Metadata => Topic started by: poihths on November 02, 2017, 10:39:42 AM

Title: Changing the "Rotation" tag in a 3GP file
Post by: poihths on November 02, 2017, 10:39:42 AM
I have several .3gp video files shot on smartphones that share a common problem: under certain circumstances, the video gets displayed upside-down. The Exiftool documentation shows 3gp as a read/write format.

The files display correctly when viewed in the Finder on an iMac running the latest & greatest OS X. However, they display upside-down on the iMac in Lightroom and Premiere.

The files display upside-down in the latest & greatest Windows 10 when displayed with "Movies and TV", "Movie Maker", "Photos" and "Windows Media Player." They display correctly in Windows 10 using Quicktime.

Exiftool shows a data time "Rotation" with a value of "180". It would seem that some applications read and act upon that value, and others don't.

I confess to being utterly lost in the Exiftool documentation. Trying to keep things as simple as possible, I copied one of the offending videos into the same directory as Exiftool.exe on the Windows machine and wrote a little batch file that looks like this:

------------------------------------
exiftool -rotation test.3gp
pause
exiftool "-Rotation=0" test.3gp
pause
exiftool -rotation test.3gp
pause
------------------------------------

The output is as follows:

------------------------------------
C:\Software\ExifTool>exiftool -rotation test.3gp
Rotation                        : 180
C:\Software\ExifTool>pause
Press any key to continue . . .

C:\Software\ExifTool>exiftool "-Rotation=0" test.3gp
Warning: [minor] Patched incorrect time zero for QuickTime date/time tag - test.3gp
    0 image files updated
    1 image files unchanged

C:\Software\ExifTool>pause
Press any key to continue . . .

C:\Software\ExifTool>exiftool -rotation test.3gp
Rotation                        : 180

C:\Software\ExifTool>pause
Press any key to continue . . .

------------------------------------


I can see that the desired result isn't happening, but i have no idea how to get it to work.

Any help would be very much appreciated. I think I last worked with a command line interface sometime in the days of DOS 3.2 - say, about 30-40 years ago.

Bob
Title: Re: Changing the "Rotation" tag in a 3GP file
Post by: Phil Harvey on November 02, 2017, 10:59:05 AM
Hi Bob,

Sorry, you can't do this with ExifTool.  ExifTool currently has very limited write capabilities for video files.  It can only write XMP and some native date/time tags.  You need to write the video transformation matrices (QuickTime:MatrixStructure for the video track) to do this rotation.

- Phil
Title: Re: Changing the "Rotation" tag in a 3GP file
Post by: poihths on November 02, 2017, 11:05:52 AM
Thanks; good to know so I won't spend any more time trying to do what can't be done with this tool.

Are there other tools out there that can do the job? Some of these files have considerable sentimental value, so it would be nice to fix them.

Bob
Title: Re: Changing the "Rotation" tag in a 3GP file
Post by: Phil Harvey on November 02, 2017, 11:09:34 AM
ffmpeg can do just about anything with video files, but it is an incredibly complicated piece of software.  Or maybe AtomicParsely could do it.

- Phil
Title: Re: Changing the "Rotation" tag in a 3GP file
Post by: poihths on November 02, 2017, 11:50:57 AM
It turns out that you can rotate a video in Movie Maker on Windows. It's a recoding, however; you have to output the 3GP as MP4. For my purposes, that will do.

Thanks for your help!