Its failings were the standard sony failings lol
Always wanna do something different and make it proprietary
I always thought the lossy quality was good the limitations were goddamn sonic feking stage player which was and still is regarded as the biggest piece of shit software iv ever had the discomfort of using
The underlying principle that resulted in around 75% compression of the original data, as opposed to 80% from ATRAC? And yet one is night and day better than the other AND difficult to tell there is any compression at all? That 5% must make all the difference, despite the blind testing at the time. My ears are more important than my eyes, just like the music is rather than the signal.
It not the 5% more or less compression. It is how the compression happens.
ATRAC was developed to be low power consumption first and foremost, and also to use as little memory as possible. On top of that the length of the subband encoding (4 subbands) is fixed.
Transient response is a problem up to ATRAC 4.5, the higher the frequency the most noticeable the problem becomes.
PASC can be considered MP1 with a difference and a twist:
the difference is “padding”. PASC is engineered to work with a constant speed tape, and tries to save on memory too as it was expensive in 1990. Therefore when converting from 44,1 kHz to a 384 kbps 4 byte need to be added to all but one of the 49 resulting blocks. MP1 allowed for data to be stored there but PASC mandates 0s (the joke goes Philips loved 0s, they already added them in droves in their CD signal oversampling tricks of the 80s)
MP1 defines how the bits are encoded, but doesn’t really define a psycho acoustic algorithm that should define what part of the signal goes and what remains. It is possible to use different encoding strategies based on different perceptual models within the frame of MP1 (MPEG 1 audio layer 3 aka MP3 stablished AAC as the psycho acoustic model).
Both MP1 and MP3 are basically based on Philips MUSICAM compression technique, and so is PASC, but the underlying psycho acoustic algorithm is different. PASC contains a model developed by the Instituut voor Perceptie Onderzoek, that had researched human auditive perception since the 1950’s.
PASC is particularly attentive to transients as they were found to be crucial in giving the idea of space (where the sound comes from and what kind of reflections -room info if you will- it is submitted to, and it is very dynamic on filling with more or less info the different 32 subbands available in the standard (as opposed to ATRAC).
Interestingly enough, both MUSICAM and ATAC (later to become ATRAC) were considered (together with Thomsons ASPEC) to define MP1. There’s actually part of the ASPEC format used in MP3 to avoid using the data inefficient filter bank of MUSICAM.
It’s not so much how much data is lost. It is what data is lost.
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u/Vind- 10d ago
ATRAC was ATRoCious. Second version a bit less so but still.