[FFmpeg-user] V360 stabilization

[Michael Koch]

Am 02.10.2020 um 10:10 schrieb Paul B Mahol:
> On Thu, Oct 01, 2020 at 11:40:57PM +0200, Michael Koch wrote:
>> 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.
> Use correct player like mpv, which does not ignore color_trc.

A player? The output is a jpg image and it's too dark.

ffmpeg -i input.dng output.jpg


>> 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
> In my testcases, 30 out of 30 DNGs decoded just fine.

Did any of your 30 DNGs come from Adobe DNG converter V12.4, or from a 
Pentax K5 camera?

Michael