On Mon, Aug 16, 2021 at 6:38 AM Spielmops <spielm...@posteo.de> wrote:
> I want to use an audio-filter with Kdenlive. So I put the treble-filter > onto my audio and see the effects parameter. No clue, what these parameters > want. A frequency-parameter "a.frequency" with a range up to 1 Mio.? And > another one "a.f" with the same range? I try to gather information. > I do not use or develop Kdenlive. I figured out that "Mio" is German for "million," and I suspect it is somehow based on the maximum reported here: https://mltframework.org/plugins/FilterAvfilter-treble/ That comes from FFmpeg/libavformat's treble filter. MLT provides bridges to many other libraries in addition to some of its own effects. That is the limit as reported by the library. > I call > https://www.mltframework.org/plugins/PluginsFilters/ > > I find the filter "sox.treble", click on it and get: > https://www.mltframework.org/plugins/FilterSox-treble/ > > At the bottom there is the line, I#m looking for: the parameters. I click > onto this lik and get: > - 404 File not found > I fixed this broken link. The docs are generated into markdown and then into HTML. This parameter value unexpectedly included a markdown character sequence to denote a link, and I had to escape it in the docs generator. > > Where to look now? It's a SoX-filter, so I look for SoX: > http://sox.sourceforge.net/sox.html > > Now, that should it be. I look for treble and get a description but no > parameters. But a line that gives me hope: > - The filters are described in detail in [1]. > > Ok, I goto [1] and read: > - [1] R. Bristow-Johnson, Cookbook formulae for audio EQ biquad filter > coefficients, http://musicdsp.org/files/Audio-EQ-Cookbook.txt > > So, now the last step, I call > http://musicdsp.org/files/Audio-EQ-Cookbook.txt > > And get: > > SORRY / > \ / > \ This page does / > ] not exist yet. > > We are not responsible for SoX's docs, and again MLT is reporting what the library is giving us. > How would you proceed? > > SoX is primarily a command line tool where the typical source of documentation is the `man` command. Doing a Google search on "man sox" revelead this page that explains a lot about this effect's parameters: http://sox.sourceforge.net/sox.html#EFFECTS MLT is primarily a developer tool. I recommend that you help Kdenlive improve its UIs and docs in this area. MLT is not going to manually tweak the information coming from the other libraries. Generating things like these docs and parameters make sense for our very small developer project, but that approach may not make as much sense for an end user-facing tool such as Kdenlive.
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