Bug 366059 - Audio-only (wav) exports extremely slow with GPU / Movit / GLSL enabled
Summary: Audio-only (wav) exports extremely slow with GPU / Movit / GLSL enabled
Status: RESOLVED DUPLICATE of bug 380019
Alias: None
Product: kdenlive
Classification: Applications
Component: Video Display & Export (show other bugs)
Version: 16.04.0
Platform: Gentoo Packages Linux
: NOR normal
Target Milestone: ---
Assignee: Jean-Baptiste Mardelle
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-07-24 21:09 UTC by Peter
Modified: 2018-11-10 14:22 UTC (History)
2 users (show)

See Also:
Latest Commit:
Version Fixed In:
snd.noise: MOVIT+


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Description Peter 2016-07-24 21:09:42 UTC
Audio-only (wav) exports / renders are extremely slow when GPU acceleration / movit / glsl are enabled, as soon as you turn them off the render speed of audio-only jumps up considerably.

A good way to prove this is to take a short video, generate a script for an audio only export, run the script, take the glsl.=1out of the script and re-run it. Note the change in running speed. The problem is also evident if you simply render a wave from inside kdenlive, and then do the same thing after disabliing gpu rendering.

Feels like melt is rendering the whole frame and then discarding the video rather than ignoring the video because its audio-only.

This also happened when I use flac audio-only (video_off=1 f=flac acodec=flac vn=1) - despite the explicit video_off and vn settings, the slowness was still apparent, once again as soon as I removed glsl.=1 from the generated script.

The bug exists both in 16.04 and the latest git version.

Reproducible: Always

Steps to Reproduce:
1. Drag a movie clip into a fresh project with movit enabled
2. Generate an audio-only (wav) script
3. Run the script

Actual Results:  
Very slow rendering, almost real-time.

Expected Results:  
Speedy audio-only render, much much faster than real-time.

Removing glsl.=1 from the generated script makes it run a gazillion times faster.
Comment 1 emohr 2018-11-10 14:22:18 UTC
Unfortunately MOVIT (GPU effects) is not stable and not ready for production use.

*** This bug has been marked as a duplicate of bug 380019 ***