[vtkusers] vtkAVIWriter with renderer gradient background shows distinct lines

[Andras Lasso]

In 3D Slicer we use VP9 codec with MKV container and it works well. VP9 is not as widely used as H264 but it is completely royalty-free and offers good compression ratio and acceptable speed even with lossless settings.

We build required libraries (VP9, libwbm, yasm) using CMake superbuild on Windows/Linux/Mac. Container file reading/writing implementation is here: https://github.com/IGSIO/IGSIO/blob/master/Source/VideoIO/MKV/vtkMKVWriter.cxx, and VP9 codec is here: https://github.com/IGSIO/SlicerIGSIO/blob/master/VideoIO/Codecs/vtkVP9VolumeCodec.cxx.

Andras

From: vtkusers <vtkusers-bounces at public.kitware.com> On Behalf Of Cory Quammen
Sent: Tuesday, November 27, 2018 10:11 AM
To: santosh <scbiradar at gmail.com>
Cc: vtkusers <vtkusers at vtk.org>
Subject: Re: [vtkusers] vtkAVIWriter with renderer gradient background shows distinct lines

I'm afraid I don't have a lot of experience with the AVI compression options. You might experiment with vtkAVIWriter::SetCompressorFourCC() to see if you can find a compressor that gives more satisfactory results.

Personally I prefer to dump animation frames and assemble them with outside video software.

Cory

On Tue, Nov 27, 2018 at 9:26 AM Santosh Biradar <scbiradar at gmail.com<mailto:scbiradar at gmail.com>> wrote:
Thanks for the quick response Cory.
I tried setting quality to 0,1,2. The quality of the movie was best for 2 and worst for 0 but the background remained the same in each case.
The quality of the output of the  filter (in this case, a vtkContourFilter) reduces with reduction in SetQuality but the background remains of the same quality.
There is no difference in the quality of the background.

I also get the same behavior in Paraview's Save Animation feature (version 5.5 on windows)

Thanks,
Santosh


On Tue, Nov 27, 2018 at 7:29 PM Cory Quammen <cory.quammen at kitware.com<mailto:cory.quammen at kitware.com>> wrote:
Sounds like quantization/compression artifacts. You can try changing the quality setting to reduce compression via vtkAVIWriter::SetQuality().

HTH,
Cory

On Tue, Nov 27, 2018 at 8:55 AM Santosh Biradar <scbiradar at gmail.com<mailto:scbiradar at gmail.com>> wrote:
I am trying to create a movie of an animation using vtkAVIWriter.
The renderer has a gradient background. The .avi file created has distinct lines/bands in the background because of the gradient. Is it possible to get rid of these lines. I notice that if I use a vtkBMPWriter and write an image, the image seems fine without any such lines/bands.

A code snippet of what I am doing:


window_to_image = vtk.vtkWindowToImageFilter()
window_to_image.SetInput(renWin.GetRenderWindow())
window_to_image.SetInputBufferTypeToRGB()
window_to_image.ReadFrontBufferOff()

writer = vtk.vtkAVIWriter()
writer.SetInputConnection(window_to_image.GetOutputPort())

I am running python wrapper of VTK-6.3.0 on windows



Thanks,

Santosh


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--
Cory Quammen
Staff R&D Engineer
Kitware, Inc.


--
Cory Quammen
Staff R&D Engineer
Kitware, Inc.
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