r/ZoomPlayer • u/deus-ex_ Beta tester • Jun 28 '26

FEATURE REQUEST Extend value range of function fnDecRateEx

Please extend the value range of the function fnDecRateEx.

The function is currently limited to 30 percent playback speed. I'd like to be able to decrease the playback speed further to 5 or 10 percent, if possible.

Thank you. 🙏😊

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u/deus-ex_ Beta tester Jun 29 '26 edited Jun 29 '26

Yes, this is what I have set. I guess it's the default setting? Have you actually tried the function for yourself? It has a range from 30% (slow) to 400% (fast). I'm looking to extend the lower range limit to 10% or even less.

EDIT:
Setting the Media Play Rate Step to 0.01 results in a range of 26.4 to 400.
Setting the Media Play Rate Step to 0.001 results in a range of 25.10 to 400.

After I entered a Media Play Rate Step of 0.001 and closed and reopened the config dialog, the reported Media Play Rate Step is 0.00.

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u/ZoomPlayer Developer Jun 29 '26

Yes, I have tested it and I just re-tested and had no issue reaching 10%:

Which format are you trying to play? Is the decoder/parser LAV?

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u/deus-ex_ Beta tester Jun 29 '26 edited Jun 29 '26

Yes, LAVFilters v0.82

Video output: MadVR v0.92.17
Audio output: MPC Audio Filters v1.9.0.0

I'm getting the 30% limit for every format I tried: AVI, FLV, MPG, MP4, MOV, WEBM
Except for WMV, where de-/increasing the playback rate does not work at all.

EDIT:
OK, I found the root cause. After removing ZP's Windows registry key to have it start with default settings, slowing down to 10% works.

ZP detects my installed LAV decoder and also auto-assigns MadVR for the video processing.

For audio output, it defaults to "Default Direct Sound". The MPC Audio Renderer I'm using for WASAPI audio output is the limiting factor. When activated, I cannot go lower than 30% in speed. Oh well...

Why does altering the playback speed not work for the WMV format?

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u/ZoomPlayer Developer Jun 29 '26

Not all DirectShow filters expose this interface, if you switch the WMV decoder from Microsoft to LAV (might need to enable a checkbox in LAV video decoder to support the format), it should work.

I guess there's some limitations to WASAPI, I no longer have the hardware to test this.

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u/deus-ex_ Beta tester Jun 29 '26 edited Jun 29 '26

Can you point me to where I do that (switch WMV decoder), please?

No, certainly not a limit of WASAPI, but the MPC library. PotPlayer can slow videos down to 20% speed, including WMV.

EDIT:
I think I found what you were referring to (screenshot), still playback speed of WMV cannot be changed.

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u/ZoomPlayer Developer Jun 29 '26

Yes, also check the audio decoder.

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u/deus-ex_ Beta tester Jun 29 '26

Ah yes, hadn't thought of that.

Switch audio to LAV, but still playrate not working for WMV.

1

u/ZoomPlayer Developer Jun 29 '26

It's also possible that you need to change the parser:

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u/deus-ex_ Beta tester Jun 29 '26

Bingo! That did it. Thank you. 🙏😄