HDCD CDs and transcoding

[simoncn]

I don't see how the FFmpeg filter could know in advance whether or not HDCD information is present at some point in the audio that the filter hasn't read yet (so that it can only apply the -6dB reduction if HDCD information is present). In contrast, processing performed at the ripping stage can scan the whole file and identify whether the file is HDCD or not.

Forum discussions that I have seen suggest that the user can compensate for this -6dB reduction by adding album gain or track gain tags to non-HDCD files. This isn't ideal but is probably the best that can be achieved with the filtering approach.