Behaviour of Keep Original Vs Downmix to Stereo
Consider for example playing an mkv containing h264 and aac5.1 on a renderer that plays these streams but only in m2ts. The device profile will feature a transcode line to remux the container, but the audio stream will be copied not re-encoded. Currently the command line that's being fed to FFmpeg is to downmix which, in the case of aac5.1 > aac 2 channel will fail (due to an FFmpeg problem). Since I'm serving from a NAS I wouldn't really want it set on preserve original, because this seems to break DTS remuxing (another FFmpeg limitation) but it would also cost a lot of additional CPU power for those occasions that I really am transcoding audio.
Are there really renderers that can't downmix themselves (i.e. that would need everything forcing to 2 channel)?
Serviio 2.1 package for Synology NAS - with limited hardware transcoding support!