I was trying to capture a single window using ximagesrc. Encoding it to png and saving it gives black bordes around the image. This was the command i used.
gst-launch-1.0 ximagesrc remote=1 num-buffers=1 xid=<windowid> ! videoconvert ! pngenc ! filesink location=screenshot.png
and this is the result I've got
is there any way to remove that borders or to decrease border's alpha?
Related
I'm using GStreamer to process videos in my project. The input videos can have various formats (both resolutions and aspect-ratio). It can be for example 400x300, 1080p, 4K, 2000x1000, etc.
I would like to downscale videos automatically which are larger than 1080p. So if video is in 4K it should be downscaled to 1080p but if it is in 400x300 format it should be kept in original format.
I've found videoscale pipeline plugin but it does not work as I would like. It is changing scale up and down without any distinctions. Also it is not changing sizes proportionally when only width or height is provided.
Do you know any straightforward way in GStreamer to downscale resolutions automatically to desired size?
GStreamer's caps allow ranges. So I believe you are looking for something like this:
video/x-raw,width=[1,1920],height=[1,1080],pixel-aspect-ratio=1/1
This will keep the same aspect ratio but scales down in case it is required to fit into 1920x1080.
E.g.
gst-launch-1.0 videotestsrc ! video/x-raw,width=4000,height=2000 ! videoscale ! video/x-raw,width=[1,1920],height=[1,1080],pixel-aspect-ratio=1/1 ! autovideosink
Will be scaled down to 1920x960.
And:
gst-launch-1.0 videotestsrc ! video/x-raw,width=400,height=200 ! videoscale ! video/x-raw,width=[1,1920],height=[1,1080],pixel-aspect-ratio=1/1 ! autovideosink
Will stay at 400x200.
When I rotate a test pattern 90 degrees:
gst-launch-1.0 -v videotestsrc ! video/x-raw,width=1280,height=720 ! videoflip method=clockwise ! videoconvert ! ximagesink
I have two problems:
The output window is distorted unless I maximize it
The output video window, when maximized, falls outside of my 1920*1080 monitor, so that I only see the upper half of the testsrc pattern
It could be due to ximagesink? If I remember correctly there is some additional application logic required to match window dimensions and buffer dimensions. Usually xvimagesink or glimagesink yield in better results.
I'm launching a gst-launch-1.0 that captures camera images with nvgstcamera. The images are encoded to VP9 video. The video is tee'd to a filesink that saves the video in a webm container and to a VP9 decoder that pipes the images into an appsink.
Later, I want to extract frames from the saved video and run them through the application again. It is important that the frames are absolutely identical to the ones that were piped into the appsink during video capture.
Unfortunately, the decoded frames look slightly different, depending on how you extract them.
A minimal working example:
Recording:
$ gst-launch-1.0 nvcamerasrc ! "video/x-raw(memory:NVMM), format=NV12" ! omxvp9enc ! tee name=splitter \
splitter. ! queue ! webmmux ! filesink location="record.webm" \
splitter. ! queue ! omxvp9dec ! nvvidconv ! "video/x-raw,format=RGBA" ! pngenc ! multifilesink location="direct_%d.png"
Replaying with nvvidconv element:
$ gst-launch-1.0 filesrc location=record.webm ! matroskademux ! omxvp9dec \
! nvvidconv ! pngenc ! multifilesink location="extracted_nvvidconv_%d.png"
Replaying with videoconvert element:
$ gst-launch-1.0 filesrc location=record.webm ! matroskademux ! omxvp9dec \
! videoconvert ! pngenc ! multifilesink location="extracted_videoconvert_%d.png"
Testing image differences:
$ compare -metric rmse direct_25.png extracted_nvvidconv_25.png null
0
$ compare -metric rmse direct_25.png extracted_videoconvert_25.png null
688.634 (0.0105079)
nvvidconv:
videoconvert:
My guess is that this has to do with the I420 to RGB conversion. So videoconvert seems to use a different color conversion than nvvidconv.
Launching the pipeline with gst-launch -v shows that the element capabilities are basically the same for both replay pipelines, the only difference is that videoconvert uses RGB by default, while nvvidconv uses RGBA. Adding the caps string "video/x-raw,format=RGBA" behind videoconvert makes however no difference in color conversion.
Note that this is on an Nvidia Jetson TX2 and I would like to use hardware accelerated gstreamer plugins during recording (omxvp9enc, nvvidconv), but not during replay on another machine.
How can I extract images from the video that are identical to the images running through the pipeline during recording, but without the use of Nvidia's Jetson-specific plugins?
Check for colorimetry information - https://developer.gnome.org/gst-plugins-libs/stable/gst-plugins-base-libs-gstvideo.html#GstVideoColorimetry
Videoconvert for example take these into account when converting images. Depending on the caps found at input and output.
You probably have to check what the Tegra is doing here. Most likely there is a difference if the signal is interpreted as full range or tv range. Or the matrices differ from 601 and 709.
Depending on precision there may still be some loss during the conversion. For metrics at video codecs it may make sense to stay at YUV color space and use only RGB for display if you must.
I wrote a video player based on gstreamer. Now I need to display status images on top of playing video when some event is occurred. I tried following pipeline for testing purposes
gst-launch-1.0 videotestsrc ! videomixer name=mix ! videoconvert ! autovideosink filesrc location=pic.jpg ! jpegdec ! videoconvert ! imagefreeze ! mix.
to display image (implemented in C). To hide image I set pipeline to GST_STATE_READY, unlink and remove location, jpegdec, videoconvert and imagefreeze and set pipeline back to playing state but that doesn't work (video is not playing anymore).
Could someone suggest the right way of showing and hiding images on top of playing video?
Myself trying to play a yuv file(IP_Traffic_12820x720_32QP.yuv) wth gstreamer.I am only possible to see the file in yuv file player by setting the width and height as 1280 and 720 respectively.How can I set this resolution in gstreamer pipeline to view the image.
Please help
You can set the resolution of your raw video using a capsfilter. Try something like this from the command line:
gst-launch-0.10 filesrc location=input.yuv ! video/x-raw-yuv,width=1280,height=720,framerate=30/1 ! ffmpegcolorspace ! autovideosink
From code, you need to create a capsfilter element and then set it's caps property. (see: http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-plugins/html/gstreamer-plugins-capsfilter.html)
Note: for gstreamer-1.0 you would use video/x-raw instead of video/x-raw-yuv, and videoconvert instead of ffmpegcolorspace.