[FFmpeg-user] V360 stabilization

[Michael Koch]

Am 01.10.2020 um 22:11 schrieb Paul B Mahol:
> On Tue, Sep 29, 2020 at 10:54:54PM +0200, Michael Koch wrote:
>> Hello all,
>>
>> I've programmed a C# workaround for stabilization of 360° videos. The
>> procedure is as follows:
>>
>> 1. FFmpeg: From each frame of the equirectangular input video, extract two
>> small images which are 90° apart in the input video. I call them A and B
>> images.
>>
>> 2. C# code: Analyze the x and y image shift from subsequent A and B images.
>> Calculate how the equirectangular frames must be rotated (yaw, pitch, roll)
>> to compensate the image shifts. This part wasn't easy. Two rotation matrices
>> and one matrix multiplication are required. Write the results to a *.cmd
>> file.
>>
>> 3. FFmpeg: Read the *.cmd file and apply the rotations with the v360 filter.
>> The output video is stabilized.
>>
>> For details and source code please have a look at chapter 2.78 in my book:
>> http://www.astro-electronic.de/FFmpeg_Book.pdf
>>
>> If anyone wants to implement this in FFmpeg, please feel free to do it.
> Better upload DNG files that do not decode with FFmpeg.

In this message
http://ffmpeg.org/pipermail/ffmpeg-user/2020-August/049681.html
you find a link to many DNG images which FFmpeg can't decode correctly. 
There is no error message, but the result is much too dark with low 
saturation.

I did convert a RAW image from a Canon 6D to DNG with Adobe DNG 
Converter V12.4. FFmpeg is unable to decode this DNG image. See this 
message for details:
http://ffmpeg.org/pipermail/ffmpeg-user/2020-August/049738.html
You can download the DNG image here (I will delete it from my webspace 
in a few days):
www.astro-electronic.de/IMG_3459.dng

I did also try a RAW image from a Canon 5D-MK4 with the same negative 
result.

A friend gave me a DNG image that was written by his Pentax K5 camera. 
Same negative result.

Summary: I did try DNG images from 4 different sources and in 4 of 4 
cases FFmpeg failed.

Michael