how to "sharpen audio" ?

[hydra3333]

Hello,

Some old moves, eg black and white ones, tend to have what appears to be somewhat soft or muffled audio.

I currently use ffmpeg to detect volume levels and adjust ... however I wonder if there is such a thing as "sharpening audio" in an equivalent way to sharpening video ? Dialogue, not music. I'm not even sure of what terminology to use.

I asked here http://forum.videohelp.com/threads/381309-not-sure-how-to-frame-question-sharpen-old-audio with a few suggestions arising. eg
1. use a gui program like audacity (I have a cli based workflow so that wouldn't work for me)
2. use an "exciter" per https://en.wikipedia.org/wiki/Exciter_(effect) however I'm not sure if ffmpeg or SOX has one
3. There is Crystality (spectral band replication) filter in ffdshow - the ffmpeg doco doesn't sound the same: "Simple algorithm to expand audio dynamic range" although it might be
4. maybe ffmpeg audio filters such as
https://www.ffmpeg.org/ffmpeg-all.html#equalizer
https://www.ffmpeg.org/ffmpeg-all.html#anequalizer
https://www.ffmpeg.org/ffmpeg-all.html#dynaudnorm

After a goggle, I have tried these in a .bat file
"%ffmpegexex64%" -i "%fINPUT%" -vn -filter:a crystalizer=i=2:c=1 -c:a pcm_s32le -f wav -y "%fOUTPUT1%"
"%ffmpegexex64%" -i "%fINPUT%" -vn -filter:a equalizer=f=31.5:width_type=o:width=1:g=-12,equalizer=f=63:width_type=o:width=1:g=-6,equalizer=f=125:width_type=o:width=1:g=-3,equalizer=f=250:width_type=o:width=1:g=-1.5,equalizer=f=500:width_type=o:width=1:g=-0.7,equalizer=f=1000:width_type=o:width=1:g=-0.25,equalizer=f=8000:width_type=o:width=3:g=1 -c:a pcm_s32le -f wav -y "%fOUTPUT2%"
which didn't seem to make a huge amount of difference for the crummy old sources.

Suggestions and advice would be appreciated.

[Ghitulescu]

I believe "exciter" is the term you're looking for.

[hydra3333]

Thank you. I was hoping for advice on something to use and how.

I noticed this https://sourceforge.net/projects/crystality/ where its readme says
Crystality audio DSP Plugin README file
Plugin for realtime 'remastering' sound leaned by lossy compression
Bandwidth Extender (aka Exciter), Harmonic Booster and 3D Echo.

I wonder, would this be the same as ffmpeg's Crystalizer - the ffmpeg doco doesn't sound the same: "Simple algorithm to expand audio dynamic range" ?
https://ffmpeg.org/ffmpeg-all.html#crystalizer

[raffriff42]

lines breaks added for clarity:
"%ffmpegexex64%" -i "%fINPUT%" -vn
-filter:a
equalizer=f=31.5:width_type=o:width=1:g=-12,
equalizer=f=63:width_type=o:width=1:g=-6,
equalizer=f=125:width_type=o:width=1:g=-3,
equalizer=f=250:width_type=o:width=1:g=-1.5,
equalizer=f=500:width_type=o:width=1:g=-0.7,
equalizer=f=1000:width_type=o:width=1:g=-0.25,
equalizer=f=8000:width_type=o:width=3:g=10
-c:a pcm_s32le -f wav -y "%fOUTPUT2%"
which didn't seem to make a huge amount of difference for the crummy old sources.try gain=10 @ 8000 Hz; that should make a difference - if there is any high frequency information to recover. To see if there is, use Audacity plot spectrum (http://manual.audacityteam.org/man/plot_spectrum.html).