[FFmpeg-devel] [PATCH] tools: add audio normalize script example.

[Clément Bœsch]

On Sun, Mar 24, 2013 at 12:40:40AM +0100, Stefano Sabatini wrote:
[...]
> > +ebumeta=$($analysis_cmd "amovie='$in',ebur128=metadata=1")
> 
> Note: this is broken in case $in contains filtergraph special chars
> ("," or ":"), using tools/ffescape to fix it may be a possibility.
> 

Calling tools/ffescape will cause some path problems depending on the
setup. I'd better leave it aside for now, or escape manually in the
script.

> > +[ $? -ne 0 ] && exit 1
> > +for i in $(echo "$ebumeta" | xargs); do
> > +    [ "$i" != "" ] && loudness=$i
> > +done
> > +adjust=$(echo "$ref-($loudness)"|bc)
> > +if [ "$adjust" = "0" ]; then
> > +    echo "No normalization needed for $in"
> > +else
> > +    echo "Adjust $in by ${adjust}dB"
> > +    set -x
> > +    ${FFPATH}ffmpeg -i "$in" -af volume=${adjust}dB $ffopt "$out"
> > +fi
> 
> The script would be nicer if written in Perl/Python/Equivalent, but
> don't consider this like a blocker.

Sure whatever; rewritten in Python.

-- 
Clément B.
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From 1b55312a028a56fcabc257c9a09b1d2c045198f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= <ubitux at gmail.com>
Date: Mon, 18 Mar 2013 04:02:51 +0100
Subject: [PATCH] tools: add audio normalize script example.

---
 tools/normalize.py | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100755 tools/normalize.py

diff --git a/tools/normalize.py b/tools/normalize.py
new file mode 100755
index 0000000..ef058bc
--- /dev/null
+++ b/tools/normalize.py
@@ -0,0 +1,33 @@
+#!/usr/bin/env python2
+
+import sys, subprocess
+
+if len(sys.argv) > 1:
+    ifile  = sys.argv[1]
+    encopt = sys.argv[2:-1]
+    ofile  = sys.argv[-1]
+else:
+    print 'usage: %s <input> [encode_options] <output>' % sys.argv[0]
+    sys.exit(1)
+
+analysis_cmd  = 'ffprobe -v error -of compact=p=0:nk=1 '
+analysis_cmd += '-show_entries frame=metadata:tags=lavfi.r128.I -f lavfi '
+analysis_cmd += "amovie='%s',ebur128=metadata=1" % ifile
+try:
+    probe_out = subprocess.check_output(analysis_cmd, shell=True)
+except subprocess.CalledProcessError, e:
+    sys.exit(e.returncode)
+loudness = ref = -23
+for line in probe_out.splitlines():
+    sline = line.rstrip()
+    if sline:
+        loudness = sline
+adjust = ref - float(loudness)
+if abs(adjust) < 0.0001:
+    print 'No normalization needed for ' + ifile
+else:
+    print "Adjust %s by %.1fdB" % (ifile, adjust)
+    norm_cmd  = ['ffmpeg', '-i', ifile, '-af', 'volume=%fdB' % adjust]
+    norm_cmd += encopt + [ofile]
+    print ' => %s' % ' '.join(norm_cmd)
+    subprocess.call(norm_cmd)
-- 
1.8.2

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