On 23-03-2019 04:40 PM, Michael Koch wrote:
Am 23.03.2019 um 12:00 schrieb Rex East:
On Sat, Mar 23, 2019 at 7:46 PM Michael Koch
<astroelectro...@t-online.de> wrote:
As far as I know, rotating without re-encoding isn't possible. Try
this:
ffmpeg -i input.webm -vf rotate=PI/2 output.webm
Thank you Michael for the reply and information.
However, that command resulted in the video being cropped to a square
(original video is in portrait mode), and there is still significant
quality loss...
then you could pad the video before applying the rotate filter, and
crop it after the rotate filter:
-vf pad=iw:iw:-1:-1,rotate=PI/2,crop=xxx:ih
where xxx is the height of the input video
rotate has options for output size and can accommodate the rotated
output, see https://ffmpeg.org/ffmpeg-filters.html#toc-rotate
*
*But if re-encoding is acceptable, then transpose is the suitable
filter. If streamcopying is required, then the appropriate side-data
element has to be generated and stored. For Matroska family files, I
don't see a specific element available for display orientation. I do see
a 3D projection mapping tag element which could conceivably used by
setting projection type to rectangular and a non-zero roll value (yaw,
pitch = 0). However, ffmpeg does not write the side-data for this
purpose, nor does it read it as such. Not to mention I don't know if
other consumers (players, editors) look at it either.
Gyan
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