Pass extra video filters to takeScreenshots

[hdn8]

Sometimes for example a video has a rotation value, if it was recorded on a mobile for example, and the screenshot will come out rotated according to the "metadata.stream.tags.rotation" field. Consider either passing a 'correctRotation' option to takeScreenshots (or do it automatically).

For correcting rotation I use code such as:

                var rotation = null;
                for (var i=0;i<metadata.streams.length;i++){
                    if (metadata.streams[i].tags.rotate){
                        rotation = metadata.streams[i].tags.rotate;
                    }
                }                    

                if (rotation == '180'){
                    extra_vf = 'scale=iw*sar:ih,hflip,vflip';
                } else if (rotation == '90') {
                    extra_vf = 'scale=iw*sar:ih,transpose=1';
                } else if (rotation == '270') {
                    extra_vf = 'scale=iw*sar:ih,transpose=1';
                } else {
                    extra_vf = 'scale=iw*sar:ih';
                }

metadata comes from ffprobe, could of course just have a simple option input and the user do the first part i.e.:

                     .takeScreenshots({
                            count: 1,
                            timemarks: ['50%'],
                            rotation: '180'
                            size: '?x480'
                    }

extra_vf then could be added to the filter_complex and voila!

[jpwilliams]

Having this exact issue right now. Are you saying it IS possible to rotate the thumbnails?

[njoyard]

Yeah, I've been looking for a way for takeScreenshots to work with filters already set on the command.

[hdn8]

Nope, a suggestion for improvement only, and adding extra filters to the command manually conflicts with the filters in the takeScreenshots command I think. I think it'd make more sense incorporating an auto-correct for orientation by default, I cant think of a scenario where a rotated screenshot would be preferable.

[njoyard]

Your remark is valid for rotation, but we should enable filters with screenshots anyway. There are other filters that may be useful.

[hdn8]

True, would be useful to be able to apply other filters.

[friday]

FFMPEG now auto rotate video based on metadata by default, so if you run 2.7, nightly or build from the git master branch you don't actually need the filters for this purpose. https://trac.ffmpeg.org/ticket/515#comment:12

[njoyard]

Thanks for the information @friday

[hdn8]

Good to know, thanks

On Thu, 18 Jun 2015 at 08:24 Nicolas Joyard notifications@github.com
wrote:

Thanks for the information @friday https://github.com/friday

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