discogs link
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input: 20 sec pink noise (WN trought 6pole 'pink' filter, simple pseudo-random
numbers generation, extended with XOR)
limiter: voxengo elephant2, default settings, 4x os, roof -0.2db, test dependant
input gain.
decoding: outputs decodeded with reaper 2.55
meter: SSL X-ISM
### test 1 -12db rms:
output wav (-12db_rms_24bit.wav): 24bit, 44100hz, no dither
* result: no ISP & no clipping
output mp3 (-12db_rms_320kbps.mp3): lame 3.98, CBR 320kbps, normal q
* result: no ISP & no clipping on decode
output mp3 (-12db_rms_96kbps.mp3): lame 3.98, CBR 96kbps, normal q
* result: no ISP & no clipping on decode
output flac (-12db_rms_q8.flac): flac 1.2.1, 24bit, q8
* result: no ISP & no clipping on decode
output flac (-12db_rms_q0.flac): flac 1.2.1, 24bit, q0
* result: no ISP & no clipping on decode
### test 2 -6db rms:
output wav (-6db_rms_24bit.wav): 24bit, 44100hz, no dither
* result: no ISP & no clipping
output mp3 (-6db_rms_320kbps.mp3): lame 3.98, CBR 320kbps, normal q
* result: ISP present & clipping on decode
output mp3 (-6db_rms_96kbps.mp3): lame 3.98, CBR 96kbps, normal q
* result: ISP present & clipping on decode
output flac (-6db_rms_q8.flac): flac 1.2.1, 24bit, q8
* result: ISP present & no clipping on decode
output flac (-6db_rms_q0.flac): flac 1.2.1, 24bit, q0
* result: no ISP & no clipping on decode
### Tests summary:
Lower RMS levels for both MP3 and FLAC decode with no clipping and ISP.
Decoding of mp3 streams with higher RMS level introduce clipping,
but when normalized, ISPs are not present. Higher RMS level flac q8 does
not clip, but strangly ISP are present. Lower compression q0 for FLAC preforms
very well for higher RMS values.
The tested compressors deal much better with lower RMS values.
lame -b 320 --clipdetect [file]
...
WARNING: clipping occurs at the current gain. Set your decoder to decrease
the gain by at least 0.1dB or encode again using --scale [arg]
(For a suggestion on the optimal value of [arg] encode
with --scale 1 first)