How to use GstVideoAffineTransformationMe
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How to use GstVideoAffineTransformationMe
 
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Re: How to use GstVideoAffineTransformationMe
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On So, 2016-05-15 at 16:57 -0700, Grégoire Gentil wrote:
> Hello, > > I'm interested to use GstVideoAffineTransformationMeta in > gstglimagesink, especially in gst_glimage_sink_on_draw: > > https://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/ext/gl/gstglimagesink.c#n2028 > > I have a pad probe installed in my pipeline in which I do: > > static GstPadProbeReturn cb_have_data(GstPad *pad, GstPadProbeInfo > *info, CustomData *data) { > > GstBuffer *buffer = gst_pad_probe_info_get_buffer (info); > > GstVideoAffineTransformationMeta *meta = > gst_buffer_add_video_affine_transformation_meta (buffer); something like info->data = gst_mini_object_make_writable (info->data); and then get the buffer. Apart from that what you're doing there should work. -- Sebastian Dröge, Centricular Ltd · http://www.centricular.com _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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Re: How to use GstVideoAffineTransformationMe
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Re: How to use GstVideoAffineTransformationMe
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In reply to this post by Gregoire Gentil
On 16/05/16 01:57, Grégoire Gentil wrote:
> Hello, > > I'm interested to use GstVideoAffineTransformationMeta in > gstglimagesink, especially in gst_glimage_sink_on_draw: > > https://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/ext/gl/gstglimagesink.c#n2028 > > > I have a pad probe installed in my pipeline in which I do: > > static GstPadProbeReturn cb_have_data(GstPad *pad, GstPadProbeInfo > *info, CustomData *data) { > > GstBuffer *buffer = gst_pad_probe_info_get_buffer (info); > > GstVideoAffineTransformationMeta *meta = > gst_buffer_add_video_affine_transformation_meta (buffer); > > //To be modified > const gfloat matrix[16] = { > 0.1f, 0.0f, 0.0f, 0.0f, > 0.0f, 1.0f, 0.0f, 0.0f, > 0.0f, 0.0f, 1.0f, 0.0f, > 0.0f, 0.0f, 0.0f, 1.0f, > }; > > gst_video_affine_transformation_meta_apply_matrix (meta, matrix); > > > But when the code reaches gst_glimage_sink_on_draw, af_meta = > gst_buffer_get_video_affine_transformation_meta > (gl_sink->stored_buffer[0]); is NULL. > > Any idea how I could use GstVideoAffineTransformationMeta to have my > own transform matrix? element that will add the GstVideoAffineTransformation so that's to be expected. With the latest master of gst-plugins-bad, you can use gltransformation which will build the GstVideoAffineTransformation for you and glimagesink/glvideomixer will use that instead of gltransformation performing a render pass. Cheers -Matt > Thanks in advance, > > Grégoire > _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: How to use GstVideoAffineTransformationMe
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Re: How to use GstVideoAffineTransformationMe
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On 17/05/16 19:10, Grégoire Gentil wrote:
> > > On 05/17/2016 10:02 AM, Matthew Waters wrote: >> On 16/05/16 01:57, Grégoire Gentil wrote: >>> Hello, >>> >>> I'm interested to use GstVideoAffineTransformationMeta in >>> gstglimagesink, especially in gst_glimage_sink_on_draw: >>> >>> https://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/ext/gl/gstglimagesink.c#n2028 >>> >>> >>> >>> I have a pad probe installed in my pipeline in which I do: >>> >>> static GstPadProbeReturn cb_have_data(GstPad *pad, GstPadProbeInfo >>> *info, CustomData *data) { >>> >>> GstBuffer *buffer = gst_pad_probe_info_get_buffer (info); >>> >>> GstVideoAffineTransformationMeta *meta = >>> gst_buffer_add_video_affine_transformation_meta (buffer); >>> >>> //To be modified >>> const gfloat matrix[16] = { >>> 0.1f, 0.0f, 0.0f, 0.0f, >>> 0.0f, 1.0f, 0.0f, 0.0f, >>> 0.0f, 0.0f, 1.0f, 0.0f, >>> 0.0f, 0.0f, 0.0f, 1.0f, >>> }; >>> >>> gst_video_affine_transformation_meta_apply_matrix (meta, matrix); >>> >>> >>> But when the code reaches gst_glimage_sink_on_draw, af_meta = >>> gst_buffer_get_video_affine_transformation_meta >>> (gl_sink->stored_buffer[0]); is NULL. >>> >>> Any idea how I could use GstVideoAffineTransformationMeta to have my >>> own transform matrix? >> >> Most likely, you're using a pipeline that does not have an upstream >> element that will add the GstVideoAffineTransformation so that's to be >> expected. >> >> With the latest master of gst-plugins-bad, you can use gltransformation >> which will build the GstVideoAffineTransformation for you and >> glimagesink/glvideomixer will use that instead of gltransformation >> performing a render pass. > > Thanks for the clarification. This is interesting and I recall having > read gltransformation code but it doesn't do what I want, aka. having > a specific transformation matrix. My ultimate goal is to crop the > video. Can I do it with the existing property of gltransformation? GstVideoAffineTransformation when combined with other transformations (rotate, perspective, etc). What you can do to get a close-enough effect for small crops with a transformation matrix is scale and translate (using the scale-x, scale-y, translation-x and translation-y properties) so that you only show the cropped area however this may perform a non-uniform scale which will cause the aspect ratio to be changed and degrade the video. What needs to happen for this is that glimagesink needs to be able to understand the GstVideoCropMeta and then one can use the videocrop element to crop in GL. Cheers -Matt > Grégoir _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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