I’m using Windows 7x64, installed Audacity 2.1.0 from the .exe installer.
I need to convert the audio from blu-ray m2ts files to FLAC.
When I open an m2ts file directly with Audacity, it adds a (more or less) 50 seconds delay. If I demux the m2ts file first with TSMuxer, and open the demuxed audio file, there is no delay.
Weirdly, Audacity is able to open a m2ts file that contains TrueHD audio, but not when it has been demuxed. Demuxed files work well when the audio is DTS-HD only.
I’d like to avoid the extra demuxing step, which anyway does not work with TrueHD blu-rays.
Audacity doesn’t natively support Blu-Ray formats.
As you can see at https://www.ffmpeg.org/general.html FFmpeg only offers limited Blu-Ray support. If you try to decode the files to WAV with FFmpeg standalone (at the command-line) and you receive the same issues, then it is a limitation in FFmpeg and not Audacity.
If you only want to make simple trims to the audio you may be better off working directly with a Blu-Ray video editing app such as http://is.gd/BgRD46. Some might support bouncing the audio to other formats. Or try eac3to.