Problem with --standard, up to --quality 10
2003-08-07 16:22:38
Bored by some recent discussion about the relevance of high settings with musepack encoder, I tried to prove to myself and to other people that: - finding slight problems samples for mpc –quality 5 isn’t too difficult (even if it needed a lot of concentration to ABX problem) - these small problems will disappear with a higher bitrate. I suspect since a long time that mpc isn’t clear with cymbals. I have a lot of metal music encoded with –standard, and I often perceive some suspicious distortions with this instrument. Unfortunately, I haven’t the original for ABX test. I tested some long times ago on some cymbals sample I founded myself, but conclusions were clean for mpc. Today, I decided to try again, more seriously, and therefore I searched for a good cymbal sample in my entire library. A name quickly came into my mind : Richard Wagner… I found some sharp cymbals in his famous hit, popularized by Francis Ford Coppola. I cut some seconds, and encode them with both 1.14 and 1.15r (I’m not convinced that 1.15r is better than 1.14, and I also suspected 1.14 to be stronger on most ‘regular’ samples than 1.15r). –xlevel encoding was always enabled, to avoid clipping distortion. First, I ABXed –standard encodings. On the first cymbal attack, I was disappointed. Though I didn’t listen very carefully, I expected a more obvious difference. I jumped few seconds, and ABXed another part of the file (cymbals too) : from second 10.00 to 11.5. Results are here : STANDARD (first trial) 1.14 : 4.2 - 12/16 1.15r : 4.5 - 12/16 1.14 vs 1.15r : 9/16 (second trial) 1.14 : 4.2 - 13/16 1.15r : 4.5* - 12/16 (* mixed up original and encoded) 1.14 vs 1.15r : 2/7 Though I rated two times 1.14 at a higher level than 1.15r, I wasn’t able to distinguish them on a direct opposition. Most important thing : --standard profile is ABXable on this small part/high cymbal attack. Let see if –extreme will correct the problem : EXTREME 1.14 : 4.8 - 8/16 1.15r : 4.3 - 16/16 1.14 vs 1.15r : 13/16 (pval = 0.011) I didn’t perform a second test at this setting. Result were obvious, confirmed by the good ABX score I had with 1.15r (16/16 !) and with direct opposition (13/16). 1.15r was significantly worse, due to an annoying whistle I heard with evidence. On the other side, 1.14 was near transparent. On my quick test, I couldn’t ABXed it. I was happy, and decided to perform a last test at –insane…
Wavpack Hybrid: one encoder, one encoding for all scenarios WavPack -c4.5hx6 (44100Hz & 48000Hz) ≈ 390 kbps + correction file WavPack -c4hx6 (96000Hz) ≈ 768 kbps + correction file WavPack -h (SACD & DSD) ≈ 2400 kbps at 2.8224 MHz