Launchpad has imported 7 comments from the remote bug at http://bugzilla.audacityteam.org/show_bug.cgi?id=22.
If you reply to an imported comment from within Launchpad, your comment will be sent to the remote bug automatically. Read more about Launchpad's inter-bugtracker facilities at https://help.launchpad.net/InterBugTracking. ------------------------------------------------------------------------ On 2009-11-10T14:48:34+00:00 Richard Ash wrote: Steve: There has been an enquiry on the help forum http://audacityteam.org/forum/viewtopic.php?f=12&t=9429 and it appears that 16bit uncompressed files have dithering applied on import into Audacity (when dithering is selected in preferences for high quality conversion). Surely that should not be the case unless the imported audio is being resampled to a lower bit depth. If the default sample rate is set to 16 bit, and a 16 bit audio file is imported, then unless dither is switched off it can be seen that Audacity changes the sample values on import. Someone raised a similar issue on this list recently regarding dither being applied when a track is inverted. Martyn: One for the 'back burner' as far as 2.0 is concerned. Just found this in my inbox, sorry for the 6 month delay in responding! For the record: The dither is being applied on export (I can see that by exporting a generated 'true' silence and then looking at the wav file in a binary viewer). And no, that shouldn't be the case when a 16-bit internal representation is exported to a 16-bit file. From looking at the code, I broke this back on 17th Sept 2006 in revision 1.57 of Mix.cpp when I introduced all mixing in floats. The workaround of setting the dither pref to 'None' is good, the loss of the use of CopySamplesNoDither isn't (which did it automatically if formats matched). The subsequent gain of being able to apply -ve dB gain to a clipped mix is good however (I think this is a result of that change). The solution is not as simple as just reverting to using CopySamplesNoDither if the input and output formats are the same, since we'd have to re-introduce sensible clipping. Also, does float have as many bits of integer resolution as 24-bit int? On all platforms? If so we could keep the mixing at float and just clip and output in CopySamplesNoDither (rarely used). We have 'a' user who has gone on to a different app, and a sensible workaround. And the problem is inaudible to most (all?) of our users. But I'm not happy that I broke that and it does need addressing at some point. Richard: > One for the 'back burner' as far as 2.0 is concerned. +1 > Also, does float have as many bits of integer resolution as 24-bit int? A 32-bit or larger float does. > On all platforms? On all IEEE 754 compliant hardware, which means almost anything except a Cray supercomputer. I'm fairly certain that's anything Audacity runs on, given we don't have any 16-bit platforms. > If so we could keep the mixing at float and just clip and > output in CopySamplesNoDither (rarely used). Richard Reply at: https://bugs.launchpad.net/audacity/+bug/608964/comments/0 ------------------------------------------------------------------------ On 2009-12-04T17:17:37+00:00 Gale wrote: Same problem applies to MP3 (but not OGG). Reply at: https://bugs.launchpad.net/audacity/+bug/608964/comments/1 ------------------------------------------------------------------------ On 2010-01-29T13:48:42+00:00 James-k-crook wrote: No longer in wiki Release Checklist as of 29th Jan 2010. Reply at: https://bugs.launchpad.net/audacity/+bug/608964/comments/2 ------------------------------------------------------------------------ On 2010-01-29T20:37:19+00:00 Gale wrote: Misunderstanding - bug not fixed and still valid. Was never put on Checklist because we were at the time placing low priority bugs in "Bugzilla only" as an experiment. Reply at: https://bugs.launchpad.net/audacity/+bug/608964/comments/3 ------------------------------------------------------------------------ On 2010-03-16T23:42:02+00:00 Gale wrote: Gale: Promoted to P4 - A small minority of people do report this (I've seen four reports since the bug was raised). The noise is audible - especially in headphones- if you reimport the exported WAV and amplify it several times in the course of editing some very quiet classical piece. Reply at: https://bugs.launchpad.net/audacity/+bug/608964/comments/4 ------------------------------------------------------------------------ On 2010-07-31T04:44:30+00:00 Gale wrote: *** Bug 191 has been marked as a duplicate of this bug. *** Reply at: https://bugs.launchpad.net/audacity/+bug/608964/comments/8 ------------------------------------------------------------------------ On 2010-11-22T11:13:05+00:00 Gale wrote: Release Noting it - too many people are complaining. Reply at: https://bugs.launchpad.net/audacity/+bug/608964/comments/9 ** Changed in: audacity Status: Unknown => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/608964 Title: Select-all + Export Selected produces different .wav file -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
