time stretching audio distortion on 7.1 sources

[soapbox]

Dear Slysoft

I have a 50Hz screen, so I'm using reclock to speed-up 23.976/24p content to 25p; and then use time stretching to keep the sound at normal pitch. This all works very well, except when the audio is 7.1 (dtsma, truehd, or flac), in which case the audio output is distorted (especially noticeable on dialogue). I use best quality sinc processing setting in Reclock. No such distortions using 2.0/5.1 content or playing 7.1 without time stretch. Any ideas?

Many thanks

 

[soapbox]

Can you please also comment on this timestretching improvement solution posted in 2009:
http://touristinparadise.blogspot.co.nz/2009/04/phase-coherent-pitch-shifter-for.html

Has the default timestretching in reclock evolved past this in the last 5 years, or should I still use the above modified timestretching.dll to achieve better sound quality?

 

[soapbox]

Did some more experimenting yesterday, and I also experienced audible audio distortion on most 5.1 source tracks when using timestrecthing, not just 7.1, but it is less noticeable on 5.1 tracks.
Distortions are worst on louder dialogue.

Interestingly, if I use LAV Audio Filter to downmix these problematic 5.1/7.1 tracks down to simple stereo, then there is no distortion and audio sounds clean as a whistle - but too bad it's only stereo!

Any ideas how to get clean timestretched audio on 5.1/7.1?