[FFmpeg-devel] [PATCH] avfilter: add showfreqs filter

[Lou Logan]

On Mon, 10 Aug 2015 15:51:24 +0200, Paul B Mahol wrote:

[...]

> + at section showfreqs
> +
> +Convert input audio to video output, representing the audio power spectrum.

You can remove that comma.

> +Audio amplitude is on Y-axis while frequencies are on X-axis.

Audio amplitude is on Y-axis while frequency is on X-axis.

> +The filter accepts the following options:
> +
> + at table @option
> + at item size, s
> +Specify size of video.

For the syntax of this option, check the @ref{video size syntax,,"Video
size" section in the ffmpeg-utils manual,ffmpeg-utils}. Default is
@code{1024x512}.

> + at item mode
> +Set display mode.
> +
> +It accepts the following values:
> + at table @samp
> + at item line
> + at item bar
> + at item dot
> +
> +Specify how each frequency bin will be represented.

The above line seems to be misplaced.

> + at end table

Default is @code{bar}.

> + at item ascale
> +Set amplitude scale.
> +
> +It accepts the following values:
> + at table @samp
> + at item lin
> +Linear scale.
> +
> + at item sqrt
> +Square root scale.
> +
> + at item cbrt
> +Cubic root scale.
> +
> + at item log
> +Logarithmic scale.
> + at end table

Default is @code{log}.

> + at item fscale
> +Set frequency scale.
> +
> +It accepts the following values:
> + at table @samp
> + at item lin
> +Linear scale.
> +
> + at item log
> +Logarithmic scale.
> + at end table

Default is @code{linear}.

> + at item win_size
> +Set window size.
> +
> +It accepts the following values:
> + at table @samp
> + at item w16
> + at item w32
> + at item w64
> + at item w128
> + at item w256
> + at item w512
> + at item w1024
> + at item w2048
> + at item w4096
> + at item w8192
> + at item w16384
> + at item w32768
> + at item w65536
> + at end table

Default is @code{w2048}.

> + at item win_func
> +Set windowing function.
> +
> +It accepts the following values:
> + at table @samp
> + at item rect
> + at item bartlett
> + at item hanning
> + at item hamming
> + at item blackman
> + at item welch
> + at item flattop
> + at item bharris
> + at item bnuttall
> + at item bhann
> + at item sine
> + at item nuttall
> + at end table

Default is @code{hanning}.

> + at item overlap
> +Set window overlap. In range @code{[0, 1]}. Default is 1, which means optimal overlap
> +for selected window function will be picked.
> +
> + at item averaging
> +Set time averaging. Setting this to 0 will display current maximal peaks.

Default is 1.

> + at item color
> +Specify list of colors separated by space or by '|' which will be used to draw channel
> +frequencies. Unrecognized or missing colors will be replaced by white.
> + at end table

Can you list the acceptable colors? Would it be too annoying to allow
usage of the colors listed in ffmpeg-utils?

Please check that I got the defaults correct.