FFMPEG Audio Volume Command

[Johnbil]

I’m still driving myself crazy trying to test & correct audio volume problems on AVI files. I have a number of videos (using MP3 audio) with either too low or too high an audio volume and I’m looking to normalize them.

Is there a command line for FFMPEG or some other program to compare a file to a Target ‘Normal’ of 89 DB? I would like it to give an indication of how many DB’s are necessary to bring it up or down to 89.

Thanks in advance,
John

[Selur]

it might be possible to archive something like this using sox, but it will require a lot of reading of the sox manual (http://sox.sourceforge.net/sox.html)

ffmpeg -y -analyzeduration 500000000 -v -10 -i "Path to file" -f sox - | sox --multi-threaded --buffer 524288 -S -t sox - -n stats

will return something like (here for a stereo source):

             Overall     Left      Right
DC offset   0.000001  0.000001  0.000000
Min level  -0.157471 -0.157471 -0.156433
Max level   0.119263  0.117676  0.119263
Pk lev dB     -16.06    -16.06    -16.11
RMS lev dB    -42.19    -42.15    -42.23
RMS Pk dB     -32.12    -32.12    -32.26
RMS Tr dB     -62.14    -62.14    -62.13
Crest factor       -     20.16     20.22
Flat factor     0.00      0.00      0.00
Pk count           2         2         2
Bit-depth      14/16     14/16     14/16
Num samples     824k
Length s      17.160
Scale max   1.000000
Window s       0.050

if you don't want the statistics per channel:

ffmpeg -y -analyzeduration 500000000 -threads 8 -v -10 -i "Path to file" -f sox - | sox --multi-threaded --buffer 524288 -S -t sox - -n stat

will return something like:

Samples read:           1647360
Length (seconds):     17.160000
Scaled by:         2147483647.0
Maximum amplitude:     0.119263
Minimum amplitude:    -0.157471
Midline amplitude:    -0.019104
Mean    norm:          0.003803
Mean    amplitude:     0.000001
RMS     amplitude:     0.007773
Maximum delta:         0.097717
Minimum delta:         0.000000
Mean    delta:         0.001382
RMS     delta:         0.002022
Rough   frequency:         1987
Volume adjustment:        6.350
Done.

based on these statistics it should be possible to calculate the amount in gain is needed to reach 89db,...

ffmpegs volumedetect:

ffmpeg -y -analyzeduration 500000000 -threads 8 -i "Path to input" -af volumedetect -f null -

returns something like:

[Parsed_volumedetect_0 @ 0000000000340b00] n_samples: 1647360
[Parsed_volumedetect_0 @ 0000000000340b00] mean_volume: -42.2 dB
[Parsed_volumedetect_0 @ 0000000000340b00] max_volume: -16.1 dB

if you do this for each file, you get the max volume for each file, which should allow you to calculate the amount of volume gain per file that you want,..

[Johnbil]

Thanks, Selur. Very helpful.

[V1de0Luvr]

For "normalizing" audio from my videos, I demux and convert to WAV, then use WaveGain to set the volume, then encode to AC3 and remux. I have BAT files to do all this for me, of course. WaveGain defaults to -3 decibels, I believe, but you can override that to get to your desired loudness. Download WaveGain 1.3.1 from - http://www.rarewares.org/others.php

[Selur]

I normally adjust everything I reencode through sox to 0dB, I normallly decoder with ffmpeg pipe to sox, filter with sox and then reencode with ffmpeg or whatever encoder I need.

(This might be interesting regarding sox and it's gain options.)

[hydra3333]

Time has moved on a bit with ffmpeg.
I am seeking to adjust loudness and convert to .mp2 via .bat files and ffmpeg (only).
The outputs from these look interesting:

".\ffmpeg.exe" -y -vn -nostats -threads 8 -i ".\test.mpg" -af volumedetect -f null - > vol.max.txt 2>&1
".\ffmpeg.exe" -y -vn -nostats -threads 8 -i ".\test.mpg" -filter_complex ebur128 -f null - > vol.ebur128.txt 2>&1

If I can somehow in DOS crack out the value from lines in those files into variables, eg

[Parsed_volumedetect_0 @ 049ae8a0] max_volume: -7.7 dB

in this case into VOLM=-7.7
and

I: -25.1 LUFS

in this case into VLUFS=-25.1

and then, in DOS, calculate
adjVOLM=min(abs(VOLI),16)
adjLUFS= min(abs(max(-23-VLUFS),0)),16)

Then I can choose which to use for ffmpeg volume adjustment
eg

ffmpeg  ...volume=volume=%myvariabe%dB:precision=float  ...

per https://forum.videohelp.com/threads/352067-normalizing-audio-volume-using-new-ffmpeg-op...=1#post2209591
and
http://ffmpeg.mplayerhq.hu/ffmpeg-filters.html#volume

I'm not really sure whether to use the LUFS number or the max loudness number from "-af volumedetect"

Suggestions sought on a simpler way to do it, or pointers on how to
(a) read and crack out the values from the text files, using DOS
(b) do the calculations in DOS

Meanwhile, I'll continue googling...

[hydra3333]

Alright, brute force and a lot of ignorance then.
Looking forward to a slimline suggestion from someone smarter

@echo off
@setlocal ENABLEDELAYEDEXPANSION

@echo on
SET volFile=.\max.vol.vol.txt
".\ffmpeg.exe" -y -vn -nostats -threads 8 -i ".\test.mpg" -af volumedetect -f null - > %volFile% 2>&1
SET vbsf_vol=".\000-f1.vol.vbs"
REM @echo off
ECHO ' read vol from ffmpeg file and return the Maximum Volume value only > %vbsf_vol%
ECHO Const ForReading = 1 >> %vbsf_vol%
ECHO Dim objStdOut, objFSO , objFile, line, e, s, v, adj, er  >> %vbsf_vol%
ECHO 'Set objStdOut = WScript.StdOut  >> %vbsf_vol%
ECHO Set objFSO = CreateObject("Scripting.FileSystemObject") >> %vbsf_vol%
ECHO Set objFile = objFSO.OpenTextFile("!volFile!", ForReading) >> %vbsf_vol%
ECHO er = 1 >> %vbsf_vol%
ECHO v = 0 >> %vbsf_vol%
ECHO adj = 0 >> %vbsf_vol%
ECHO Do Until objFile.AtEndOfStream >> %vbsf_vol%
ECHO    line = lcase(objFile.ReadLine) >> %vbsf_vol%
ECHO    if instr(line,lcase("max_volume:")) > 0 then >> %vbsf_vol%
ECHO       s = instr(line,lcase("max_volume:")) + 11 >> %vbsf_vol%
ECHO       e = instr(line,lcase("dB")) - 1 >> %vbsf_vol%
ECHO       'WScript.StdOut.WriteLine "line=" ^& line >> %vbsf_vol%
ECHO       'WScript.StdOut.WriteLine s ^& " " ^& e  >> %vbsf_vol%
ECHO       if s^<=0 or e^<=0 then  >> %vbsf_vol%
ECHO          exit do >> %vbsf_vol%
ECHO       end if >> %vbsf_vol%
ECHO       v = trim(mid(line,s,e-s+1)) >> %vbsf_vol%
ECHO       'WScript.StdOut.WriteLine "string v=" ^& v >> %vbsf_vol%
ECHO       v = cdbl(v) >> %vbsf_vol%
ECHO       'WScript.StdOut.WriteLine "cdbl v=" ^& v >> %vbsf_vol%
ECHO       adj = min(abs(v),16) >> "%vbsf_vol%"
ECHO       adj = max(adj-1,0) >> "%vbsf_vol%"
ECHO       'WScript.StdOut.WriteLine "adj=" ^& adj >> %vbsf_vol%
ECHO       er = 0 >> %vbsf_vol%
ECHO       exit do >> %vbsf_vol%
ECHO    end if >> %vbsf_vol%
ECHO Loop >> %vbsf_vol%
ECHO WScript.StdOut.WriteLine adj >> %vbsf_vol%
ECHO objFile.Close >> %vbsf_vol%
ECHO set objFile = nothing >> %vbsf_vol%
ECHO set objFSO = nothing >> %vbsf_vol%
ECHO wscript.quit(er) ' 1=error. 0=ok >> %vbsf_vol%
ECHO function Max(a,b) >> %vbsf_vol%
ECHO     Max = a >> %vbsf_vol%
ECHO     If b ^> a then Max = b >> %vbsf_vol%
ECHO end function >> %vbsf_vol%
ECHO function Min(a,b) >> %vbsf_vol%
ECHO     Min = a >> %vbsf_vol%
ECHO     If b ^< a then Min = b >> %vbsf_vol%
ECHO end function  >> %vbsf_vol%
for /f "tokens=*" %%i in ('cscript //B //NOLOGO %vbsf_vol%') do set adjVOL=%%i
ECHO The value adjVOL=!adjVOL!

pause

@echo on
set ebur128File=max.vol.ebur128.txt
".\ffmpeg.exe" -y -vn -nostats -threads 8 -i ".\test.mpg" -filter_complex ebur128 -f null - > %ebur128File% 2>&1 
SET vbsf_ebur128=".\000-f1.ebur128.vbs"
@echo off
ECHO ' read ebur128 from ffmpeg file and return the Integrated Loudness I value only > %vbsf_ebur128%
ECHO Const ForReading = 1 >> %vbsf_ebur128%
ECHO Dim objStdOut, objFSO , objFile, line, e, s, v, adj, er  >> %vbsf_ebur128%
ECHO 'Set objStdOut = WScript.StdOut  >> %vbsf_ebur128%
ECHO Set objFSO = CreateObject("Scripting.FileSystemObject") >> %vbsf_ebur128%
ECHO Set objFile = objFSO.OpenTextFile("!ebur128File!", ForReading) >> %vbsf_ebur128%
ECHO er = 1 >> %vbsf_ebur128%
ECHO v = 0 >> %vbsf_ebur128%
ECHO adj = 0 >> %vbsf_ebur128%
ECHO Do Until objFile.AtEndOfStream >> %vbsf_ebur128%
ECHO    line = lcase(objFile.ReadLine) >> %vbsf_ebur128%
ECHO    if instr(line,lcase("Integrated loudness:")) > 0 then >> %vbsf_ebur128%
ECHO       line = lcase(objFile.ReadLine) >> %vbsf_ebur128%
ECHO       s = instr(line,lcase("I:")) + 2 >> %vbsf_ebur128%
ECHO       e = instr(line,lcase("LUFS")) - 1 >> %vbsf_ebur128%
ECHO       'WScript.StdOut.WriteLine "line=" ^& line >> %vbsf_ebur128%
ECHO       'WScript.StdOut.WriteLine s ^& " " ^& e  >> %vbsf_ebur128%
ECHO       if s^<=0 or e^<=0 then  >> %vbsf_ebur128%
ECHO          exit do >> %vbsf_ebur128%
ECHO       end if >> %vbsf_ebur128%
ECHO       v = trim(mid(line,s,e-s+1)) >> %vbsf_ebur128%
ECHO       'WScript.StdOut.WriteLine "string v=" ^& v >> %vbsf_ebur128%
ECHO       v = cdbl(v) >> %vbsf_ebur128%
ECHO       'WScript.StdOut.WriteLine "cdbl v=" ^& v >> %vbsf_ebur128%
ECHO       v = -23 - v >> %vbsf_ebur128%
ECHO       'WScript.StdOut.WriteLine "-23-v v=" ^& v >> %vbsf_ebur128%
ECHO       adj = min(abs(max(v,0)),16) >> %vbsf_ebur128%
ECHO       'WScript.StdOut.WriteLine "adj=" ^& adj >> %vbsf_ebur128%
ECHO       er = 0 >> %vbsf_ebur128%
ECHO       exit do >> %vbsf_ebur128%
ECHO    end if >> %vbsf_ebur128%
ECHO Loop >> %vbsf_ebur128%
ECHO WScript.StdOut.WriteLine adj >> %vbsf_ebur128%
ECHO objFile.Close >> %vbsf_ebur128%
ECHO set objFile = nothing >> %vbsf_ebur128%
ECHO set objFSO = nothing >> %vbsf_ebur128%
ECHO wscript.quit(er) ' 1=error. 0=ok >> %vbsf_ebur128%
ECHO function Max(a,b) >> %vbsf_ebur128%
ECHO     Max = a >> %vbsf_ebur128%
ECHO     If b ^> a then Max = b >> %vbsf_ebur128%
ECHO end function >> %vbsf_ebur128%
ECHO function Min(a,b) >> %vbsf_ebur128%
ECHO     Min = a >> %vbsf_ebur128%
ECHO     If b ^< a then Min = b >> %vbsf_ebur128%
ECHO end function  >> %vbsf_ebur128%
for /f "tokens=*" %%i in ('cscript //B //NOLOGO %vbsf_ebur128%') do set adjLUFS=%%i
ECHO The value adjLUFS=!adjLUFS!

pause
exit