Bug#498802: audacity: introduces noise in every audio file
Package: audacity
Version: 1.3.5-2
Severity: normal
Even the most trivial operations cause noise in the resulting audio. Here are some examples. This is after a fresh install, except that I switched to 16-bit PCM samples at 44100 Hz just to make sure that isn't the reason.
* Generate one second of silence (!!!), and export it as an uncompressed 16-bit PCM .wav file. Then take a look at the file in a hex editor, or reopen it in audacity, amplify it, and zoom in vertically. The samples range from -6 to 6!
* Open a 16-bit uncompressed .wav file, then immediately export it to the same format. The samples in the exported file are different.
* Generate a tone, export it to a .wav file, then look at the difference between two consecutive samples. Here is an example of the sample values, their differences, and the differences of those:
-7
1651 +1658
3270 +1619 -39
4908 +1638 +19
6500 +1592 -46
8085 +1585 -7
9629 +1544 -41
11137 +1508 -36
12604 +1467 -41
14018 +1414 -53
15378 +1360 -54
16677 +1299 -61
17913 +1236 -63
19075 +1162 -74
20167 +1092 -70
21174 +1007 -85
22102 +928 -79
22940 +838 -90
23692 +752 -86
24345 +653 -99
24911 +566 -87
25370 +459 -107
25735 +365 -94
As you can see, this is nowhere near a smooth curve. (This is from the default setting of 440 Hz.)
* Import the same audio file as two tracks in a single project, invert one of them, merge the two tracks, and amplify the result.
As much as I like Audacity, this behavior makes it practically useless for me. I would also really like to know where this noise comes from.
Thanks,
Sebastian Reichelt
-- System Information:
Debian Release: lenny/sid
APT prefers testing
APT policy: (500, 'testing')
Architecture: i386 (i686)
Kernel: Linux 2.6.22sreichelt
Locale: LANG=C, LC_CTYPE=de_DE (charmap=ISO-8859-1)
Shell: /bin/sh linked to /bin/dash
Versions of packages audacity depends on:
ii libasound2 1.0.16-2 ALSA library
ii libc6 2.7-13 GNU C Library: Shared libraries
ii libexpat1 2.0.1-4 XML parsing C library - runtime li
ii libflac++6 1.2.1-1.2 Free Lossless Audio Codec - C++ ru
ii libflac8 1.2.1-1.2 Free Lossless Audio Codec - runtim
ii libgcc1 1:4.3.1-9 GCC support library
ii libglib2.0-0 2.16.5-1 The GLib library of C routines
ii libgtk2.0-0 2.12.11-3 The GTK+ graphical user interface
ii libid3tag0 0.15.1b-10 ID3 tag reading library from the M
ii libjack0 0.109.2-3 JACK Audio Connection Kit (librari
ii libmad0 0.15.1b-3 MPEG audio decoder library
ii libogg0 1.1.3-4 Ogg Bitstream Library
ii libsndfile1 1.0.17-4 Library for reading/writing audio
ii libsoundtouch1c2 1.3.1-2 sound stretching library
ii libstdc++6 4.3.1-9 The GNU Standard C++ Library v3
ii libvorbis0a 1.2.0.dfsg-3.1 The Vorbis General Audio Compressi
ii libvorbisenc2 1.2.0.dfsg-3.1 The Vorbis General Audio Compressi
ii libvorbisfile3 1.2.0.dfsg-3.1 The Vorbis General Audio Compressi
ii libwxbase2.6-0 2.6.3.2.2-2 wxBase library (runtime) - non-GUI
ii libwxgtk2.6-0 2.6.3.2.2-2 wxWidgets Cross-platform C++ GUI t
audacity recommends no packages.
Versions of packages audacity suggests:
ii blop [ladspa-plugin] 0.2.8-5 Bandlimited wavetable-based oscill
ii cmt [ladspa-plugin] 1.15-3.1 Computer Music Toolkit (cmt) a col
ii omins [ladspa-plugin] 0.2.0-5 a collection of LADSPA plugins aim
ii swh-plugins [ladspa-plugin] 0.4.15-0.2 Steve Harris's LADSPA plugins
ii tap-plugins [ladspa-plugin] 0.7.0-2 Tom's Audio Processing LADSPA plug
-- no debconf information
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