melt fails to apply movit.blur from tractor.xml but works with command-line arguments

[shellljx]

Hi, When using melt with a tractor.xml file, filters such as movit.blur cannot be applied in the same way as with command-line arguments.

Details

1. Loading tractor.xml directly

Running:

melt /path/to/tractor.xml

produces the following error:

[filter avcolor_space] Invalid format glsl

2. Using command-line arguments

Running:

melt /path/to/test.mp4 -track /path/to/test2.mp4 -transition composite -attach movit.blur radius=25 -consumer sdl2

works correctly and applies the movit.blur effect to both video tracks.

Question

How should I modify my tractor.xml so that it behaves like the command-line version and successfully applies movit.blur to the tractor?

<?xml version="1.0" encoding="utf-8"?>
<mlt>
  <producer id="video">
    <property name="resource">/path/to/test.mp4</property>
  </producer>

  <producer id="video2">
    <property name="resource">/path/to/test2.mp4</property>
  </producer>

  <tractor>
    <multitrack>
      <track producer="video2"/>
      <track producer="video"/>
    </multitrack>
    <transition in="0" out="150">
      <property name="mlt_service">composite</property>
      <property name="a_track">1</property>
      <property name="b_track">0</property>
      <property name="halign">centre</property>
      <property name="valign">centre</property>
    </transition>
    <filter>
      <property name="mlt_service">movit.blur</property>
      <property name="radius">25</property>
    </filter>
  </tractor>
  <consumer>
    <property name="mlt_service">sdl2</property>
</consumer>
</mlt>

• OS: [Mac]
• MLT/melt version: CLion running the master branch of MLT

[bmatherly]

Did you know that melt can create an XML file from your command line?

Run this command:
melt /path/to/test.mp4 -track /path/to/test2.mp4 -transition composite -attach movit.blur radius=25 -consumer xml:test.mlt
Then, compare test.mlt to your xml file.

[shellljx]

Thanks, with your method I was able to generate an XML file. However, when I load it with melt, it still reports the error [filter avcolor_space] Invalid format glsl. It seems that the tractor in the XML can only use CPU effects and does not support GPU effects.

[ddennedy]

I can confirm it is not supported. In Shotcut, we disallow GPU filters on the Timeline > Output for this reason. It does work to add GPU filters to a <playlist>. You can submit a PR to add that (tractor) if you want.

[Cgun-art]

Okay so oi oi oi