For the second time in a year I've had to reacquire about 1,500 24-bit* files in their original FLAC format and reconvert them to ALAC using a 3rd party conversion tool because
24-bit ALAC conversions I had created with MC25/26 (straight conversion, no DSP) were encoded at a much higher volume than the original source FLAC, hard coding occasional clipping 'tick' sounds during peak passages into some of the files.
Basis for claim:
--If I compare MC's audio analysis results of source FLACs where the average R128 L/R peak might be around -5dB, the resulting ALAC conversion in MC produces files which typically analyze higher than 0dB, e.g., around +3dB.
--If I compare MC's audio analysis results of ALACs produced from the same source FLACs using 3rd party tools, the analysis numbers are either identical or occasionally only very slightly different.
--If I watch the DSP Studio peak level percentage readout while playing the ALACs produced by MC (no DSP/normalization), peak passages often hit and stop at 100%; it's during those periods that I can hear the characteristic clipping-related 'ticks'; the original source FLACs and ALACs produced by 3rd party tools do not, or virtually never, hit 100%.
--I can play all three test files in any other player application; the same locations in the MC-produced ALACs exhibit the 'occasional clipping ticks' whereas the 3rd party-produced ALACs do not.
So, the
clipping is definitely being hard coded into the files by MC.
--A simple listening test -- all other things the same -- also demonstrates that the MC-produced ALACs sound 'louder'.
--Playback tests can be at any reasonable actual/acoustic volume; distortion heard is not a byproduct of playback equipment.)
*I also have many tens of thousands of 16-bit files which were once FLAC, and which I once converted to ALAC with MC. Many of those show substantially greater than 0dB (e.g., > +4dB) in the R128 peak results. However, I have not ever noticed the 'clipping tick' sounds occurring in the 16-bit to 16bit conversions. I've hunted for it in such files, playing through peak solo piano passages which would definitely exhibit the artifact. So, perhaps this problem only arises with 24 bit files? Something to do with the larger dynamic range of 24 bit?Try it yourself:
1) Get a fresh 24-bit FLAC, not produced by MC.
2) Convert it to ALAC with MC (use no DSP/normalization).
3) Convert it to ALAC separately with any other tool, without any DSP/normalization turned on (e.g. dBpoweramp, EZ-CD).
4) Compare both ALACs using
any player, without any DSP/normalization turned on.
-->The MC-produced ALAC will sound louder.
5) Compare the audio analysis results of all three in MC.
-->The MC-produced ALAC will show substantially higher peak level numbers whereas the other will not.
This is a restatement and update of a similar call to attention which I posted in the MC25 forum a while back, here:
https://yabb.jriver.com/interact/index.php/topic,120734.msg834765.html#msg834765