HDCD CDs and transcoding

[simoncn]

I tried this on a couple of non-HDCD files and there is a volume reduction of approximately -6dB when using -af hdcd. From a bit of web searching, it seems this volume reduction is expected. I presume the FFmpeg hdcd filter does this to allow for a +6dB boost if/when this is signalled by an HDCD marker in the audio data (if any such markers are found). With a non-HDCD file, no markers are found and the whole file plays with a reduced volume level.

When you apply HDCD decoding as part of the ripping process, do you activate this selectively for albums that you know to be HDCD-encoded?