OK ! I'll crop the images beforehand then !
Thanks,
All the best
Geoffroy
> Le 11 oct. 2016 à 23:24, Dan Dennedy <[email protected]> a écrit :
>
> Multiple instances of crop is simply not supported/possible.
>
> On Tue, Oct 11, 2016, 2:20 PM Geoffroy Montel <[email protected]>
> wrote:
> Dear Dan
>
> Many thanks for your quick answer. It makes perfectly sense !
>
> I've always used melt native crop, and it's great, but I'm facing a slight
> issue right now when chaining two native crops. That's why I was starting to
> test avfilter crop.
>
> Anyway, let's share my experiment with chaining two native crops :
>
> Let's say I have this picture :
> http://thepopmanifesto.com/issue09/images/content/kindness-2.jpg
> Image size is 642px x 800px
>
> 1. If I want to crop center this picture, the picture aspect ratio is
> preserved
>
> melt kindness-2.jpg in=0 out=100 -attach-track crop center=1 -profile
> hdv_720_25p -consumer avformat:kindness.mp4
>
> Good !
>
> 2. If I want to crop the source image from (0,0) to (300,300), the picture
> aspect ratio is preserved and I only get the top left section of the image,
> centered in the screen
>
> melt kindness-2.jpg in=0 out=100 -attach-clip crop left=0 top=0 right=342
> bottom=500 -profile hdv_720_25p -consumer avformat:kindness.mp4
>
> Good !
>
> 3. If I want to chain the two crops, which means I want to take the top left
> section of the image, then center crop it to remove black borders, it does
> not work
>
> melt kindness-2.jpg in=0 out=100 -attach-clip crop left=0 top=0 right=342
> bottom=500 -attach-track crop center=1 -profile hdv_720_25p -consumer
> avformat:kindness.mp4
>
> First, I don't see a portion of the top left corner of the image and second,
> the image aspect ratio is not preserved.
>
> Of course this example is oversimplified, I would not have to chain two
> crops, but only one crop with the right 16/9 ratio.
> It only makes sense when I'm also adding affine transitions between the
> left/top/right/bottom crop and the center crop.
>
> Let me know if I'm not taking the right approach !
>
> Thanks again for your time and patience, all the best
>
> Geoffroy
>
>
>
>
> 2016-10-11 8:21 GMT+02:00 Dan Dennedy <[email protected]>:
> Well, basically, many avfilters are simply incompatible, and we blacklist
> some, but we have not taken the time to audit all of them, and they are
> adding many all the time. In this case, the error occurs because the output
> width and height do not match the width and height that MLT needs - as
> expected for a crop. In MLT, at some point, all video frames need to conform
> in order to allow mixing or to give the output consumer what it requested in
> a consistent manner. For that MLT automatically adds normalization filters to
> deinterlace, change field order, scale, pad, resample audio, correct # audio
> channels, etc. MLT's native crop filter is special because it has two pars:
> one that is first in normalization and one the user adds that directs the
> first one. This allows the scaling and padding filters to apply to the output
> of the first part. In short, avfilter.crop cannot work in MLT, and you should
> use the MLT crop filter. In the context of all of this, crop has an
> interesting behavior that you can observe in shotcut or similar. You first
> need to figure out what resolution and aspect ratio you want as a result, use
> that as a MLT profile, and then crop. You cannot simply say take this input
> crop X from top and bottom, compute the result for me, and give it to me.
>
> On Mon, Oct 10, 2016 at 11:09 PM Geoffroy Montel
> <[email protected]> wrote:
> Dear list,
>
> I've been trying to use avfilter crop filter, but I'm getting some errors.
>
> melt crop.jpg in=0 out=100 -attach avfilter.crop av.x=0 av.y=0 av.out_w=300
> av.out_h=300 -progress -consumer avformat:crop.mp4
>
> returns
>
> [filter avfilter.crop] Unexpected return format
>
> and the image is not cropped.
>
> Am I doing something wrong ?
>
> Thanks in advance for your help, all the best
>
> geoffroy
>
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