[FFmpeg-devel] [PATCH v4] avfilter/avf_aphasemeter: Add out-of-phase and mono detection

Michael Niedermayer michael at niedermayer.cc
Fri Jul 5 17:42:12 EEST 2019


On Wed, Jul 03, 2019 at 03:33:46PM +0200, Romane Lafon wrote:
> I've added documentation for the extension of aphasemeter filter.
> Also, I'm not sure that "phasing" is the right word to describe the
> detection.

>  doc/filters.texi              |   32 ++++++++++
>  libavfilter/avf_aphasemeter.c |  127 ++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 155 insertions(+), 4 deletions(-)
> d7ceb2e8f553300c6ba9058bd292244bc072173f  0001-avfilter-avf_aphasemeter-Add-out-of-phase-and_v4.patch
> From 1e356929e878a2081add102b77a9560647232ef8 Mon Sep 17 00:00:00 2001
> From: Romane Lafon <romane at nomalab.com>
> Date: Wed, 3 Jul 2019 15:15:16 +0200
> Subject: [PATCH] avfilter/avf_aphasemeter: Add out of phase and mono detection
> 
> Signed-off-by: Romane Lafon <romane at nomalab.com>
> ---
>  doc/filters.texi              |  32 +++++++++++
>  libavfilter/avf_aphasemeter.c | 127 ++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 155 insertions(+), 4 deletions(-)
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 700a76f239..ec8c73d558 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -20656,6 +20656,38 @@ Set color which will be used for drawing median phase. If color is
>  Enable video output. Default is enabled.
>  @end table
>  
> + at subsection phasing detection
> +
> +The filter also detects out of phase and mono sequences in stereo streams.
> +It logs the sequence start, end and duration when it lasts longer or as long as the minimum set.
> +
> +The filter accepts the following options for this detection:
> +
> + at table @option
> + at item phasing
> +Enable mono and out of phase detection. Default is disabled.
> +
> + at item tolerance
> +Set phase tolerance for mono detection, in amplitude ratio. Default is @code{0}.
> +Allowed range is @code{[0, 1]}.
> +
> + at item angle
> +Set angle threshold for out of phase detection, in degree. Default is @code{170}.
> +Allowed range is @code{[0, 180]}.
> +
> + at item duration
> +Set mono or out of phase duration until notification, expressed in seconds. Default is @code{2}.
> +
> + at subsection Examples
> +
> + at itemize
> + at item
> +Complete example with @command{ffmpeg} to detect 1 second of mono with 0.001 phase tolerance:
> + at example
> +ffmpeg -i stereo.wav -af aphasemeter=video=0:phasing=1:duration=1:tolerance=0.001 -f null -
> + at end example
> + at end itemize
> +
>  @section avectorscope
>  
>  Convert input audio to a video output, representing the audio vector

this breaks building docs

HTML	doc/ffmpeg-all.html
doc/filters.texi:20681: @subsection seen before @end table
make: *** [doc/ffmpeg-all.html] Error 1

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The worst form of inequality is to try to make unequal things equal.
-- Aristotle
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