** Description changed: - Totem plays ALAC (Apple Lossless encoding format) sound files at double speed and with distorted. - However the same input file decodes fine using alac-decoder (the generated .wav file plays normally). + (description edited) - The ALAC file (in .m4a format) was produced by ffmpeg 4:0.6-2ubuntu6. + ALAC (Apple Lossless Audeo Codec) sound files created with "ffmpeg -acodec alac" play + at double speed using totem, if the original input .wav file was monophonic. + The problem does not occur with stereo files. - It is not clear whether the bug is in totem's decoder (which is apparently not the same as alac-decoder), - or with the encoding done by ffmpeg... + The resulting mono .m4a file plays wrong on an iPOD classic, and on Linux using totem. + The same mono .m4a decodes on linux using alac-decoder to produce a *stereo* .wav file which plays at normal speed (I'm guessing that whatever the problem is with the mono ALAC .m4a file is "fixed" by duplicating the mono track). - Attached is an archive containing a test file, script, and results from my system. - - TO DEMO: - Unpack the attached archive. - Run "totem ALAC_PROBLEM_TEST.dir/output_from_Ubuntu_10.04/test.m4a" + Since the iPOD matches totem's behavior, it is extremely likely that + ffmpeg needs to be changed to generate mono ALAC files which play + correctly (OTOH, Apple might have a bug in its decoders with mono + files). + + Note: ALAC is not documented by Apple, so the only standards are Apple's + close-source implementations. + + I will attach a second demo archive. This time there are two small .wav + files, one stereo and the other mono. The mono file was created from + the stereo file using Audacity's Tracks->Stereo Track to Mono feature. ProblemType: Bug DistroRelease: Ubuntu 10.10 Package: libgstreamer0.10-0 0.10.30-1build2 ProcVersionSignature: Ubuntu 2.6.35-22.34-generic 2.6.35.4 Uname: Linux 2.6.35-22-generic x86_64 Architecture: amd64 Date: Sat Oct 16 14:48:38 2010 InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release Candidate amd64 (20100928) ProcEnviron: - PATH=(custom, user) - LANG=en_US.utf8 - SHELL=/bin/bash + PATH=(custom, user) + LANG=en_US.utf8 + SHELL=/bin/bash SourcePackage: gstreamer0.10
** Summary changed: - ALAC .m4a sound files played double speed and distorted + ffmpeg generates mono ALAC .m4a sound files which play double speed ** Attachment added: "New demo, with small stereo & mono .wav files" https://bugs.launchpad.net/ubuntu/+source/gstreamer0.10/+bug/661922/+attachment/1697242/+files/ALAC_MONO_PROBLEM.zip -- ffmpeg generates mono ALAC .m4a sound files which play double speed https://bugs.launchpad.net/bugs/661922 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
