In KDENLiVE, why is the amount of time to encode VP8 WEBM 850% more than H264 MPEG-4?

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1

Why does KDenLive take ⪆ 2 min to encode H264 MPEG-4, but ⪆ 19 min to encode VP8 WEBM?

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2

Perhaps, hardware encodement isn’t operative: [1]

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I considered whether discuss.kde.org/t/12221/2 might work, but sudo dnf5 install movit returns:

Package “movit-1.7.1-6.fc42.x86_64” is already installed.

If so, this appears more complex than I expected it to be:

  1. discuss.pixls.us/t/27599/3 ↩︎

3

HW encoding is supported by using the appropriate encoding profile like NVENC for nvidia cards and VAAPI for AMD cards.

HW-supported playback is not available because of not yet fixed issues with the movit library (that’s the reason why the option for GPU playback support is greyed out in the Settings).

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4

@berndmj, thanks. In retrospect, conflating rendering and playback was stupid on my part. However, I don’t see a HW-accelerated WEBM preset: :frowning:

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…if that’s what you mean.

5

You can create one yourself. For example, use the webm/V9 preset, click on the Save current preset as new custom preset, make sure the container is still webm, and then use the V8_VAAPI encoder in case you have an AMD GPU. For an nvidia card, try the HEVC_NVENC encoder.

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@berndmj, if it’s so simple, I’m surprised that one doesn’t come with KDENLiVE by default. Is there a potential downside you know of?

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@berndmj, perhaps, it’s less simple than we expected:

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…actually caused the encoder to crash, [1] after stating:

[vp8_vaapi @ 0x7fb1240019c0] No usable encoding profile found.

If of use, my GPU is an AMD Radeon RX 5700. [2]

  1. bugzilla.redhat.com/show_bug.cgi?id=2364080#c0 ↩︎

  2. kinfo states:

    Graphics Processor 1: AMD Radeon RX 5700
Graphics Processor 2: AMD Radeon Graphics
    ↩︎
8

Anyone can create a new render profile and even share it with the community via KDE Store to which Kdenlive has a connection for direct download. See this section for examples.

I don’t know who created the defaults available in Kdenlive and decided the formats and encoders etc. I can imagine if there is one in the KDE Store that is downloaded a lot it could be made a default profile. But this is very low on the list of priorities rn

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9

Thanks for trying it out and reporting the results. Too bad it didn’t work.

Looks like a bit more research about what ffmpeg can do and what is a reasonable and working combination of rendering parameters (like container and codec) is needed :person_shrugging:

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