Roland "Wave and SuperNATURAL Expansion" : compressed and 16-bit linear formats
On March 16th Roland presented the new Synth/Workstation
Fantom06/07/08 which, due to the 256 MByte User Memory Flash, asked a whole
series of questions on the real capacity of this memory that shares and can host
the "Wave Expansion ”(EXZ001-EXZ015), the“ SuperNATURAL Expansion ”(EXSN01-03)
and the User samples and multisamples that can be used within the Zen-Core
synthesis.
The main doubt arises from the fact that the new Fantom0 are
sold with the three expansions SuperNATURAL Acoustic Piano1 - SuperNATURAL
Acoustic Piano2 and SuperNATURAL Electric Piano 1: these expansions, which among
other things can also be canceled, occupy 120 MByte (46 % of the total capacity)
leaving a free space equal to 136 MByte which is what you get when you buy the
Synth.
What has created considerable perplexity is that in these
136 MBytes it is possible to load as many as 4 EXZ expansions, despite the fact
that each of these is a file with a size between 96 and 128 MBytes. How is it
possible to upload files larger than 400 MByte, in a flash space of 136 MByte?
Thanks to the possibility of canceling the 3 SuperNATURAL expansions, it is
possible to completely free the 256 MByte of the Flash and then load up to 8 EXZ
expansions, despite the overall capacity of the files (downloaded from
RolandCloud with the RC Manager) is about 900 MByte, more than three times
higher than the available Flash. Another question to answer: how is it possible
that the files of the three SuperNATURAL expansions, which occupy a total of 440
Mega, can only occupy 120 Mega when loaded into the flash??
The answer is very simple: from the files downloaded via RCM
(Roland Cloud Manager) and loaded into Fantom0 via USB, only a small portion of
the data present in the files is transferred to the Flash. Same thing
happens for other Roland synths such as RD-88, AX Edge and Jupiter X/XM.
To understand better, it is necessary to take a small step
back in time and go back to the years 1988-1990 in which Roland presents the
family of Modules / Synth U-110 / U-220 and U-20, D-70: it is the first step of
Roland in the use of Multisamples which are stored in ROMs and Expansion Cards.
To save available space, Roland uses a compression technique
called RS-PCM, most likely an acronym for "Reduced Size PCM". This coding,
probably not particularly efficient, is immediately abandoned.
It is a first step towards the engineering of a new compression codec called
FCE-DPCM which for the first time is used in the Flash of the JD-800 (it is
1991): all subsequent Roland synths, from the JV and XV family of the years 90,
passing to the various GM/GS modules, up to the very recent Integra-7 (2012),
FA-06/8 (2014) use this compression coding.
Roland has never
disclosed the characteristics of this codec for obvious copyright reasons, but
has given the possibility to users "geeks" to browse about this format thanks to
the fact that it is used for example in the various expansions freely
downloadable on
axial.roland.com or on the SD card
inside Integra-7.
To date, the only user who declared that he
was able to decode this codec was the WebMaster of the
dtech.lv site which among other things, to
test its capabilities, made available, a few years ago, the precious content of
the FlashROM of the samples of the JD800 in the original version (3 MByte
compressed in the FCE-DPCM format) and in the corresponding clear format at 16
linear bit (size just under 6 MByte).
Regarding the quality
of this codec, it is known that it has a variable compression ratio that reduces
the size by a factor between 1: 2 and 1: 3 and that depends on the type of
source samples (we will see it shortly): the author who decoded it describes it
as highly optimized, so much so that it has a dynamics comparable to that of a
linear 24-bit sample with small artifacts evident only in the fastest attacks.
In 2019 the Fantom arrives and for the first time the
multisamples used for the external expansions are in the linear 16 bit format:
the download of the Wave Expansion expansions (EXZ001-EXZ015) could always be
done via http://axial.roland.com / as there was no Zenology PRO yet, which
debuts the following year (May 12, 2020) as part of the Roland Cloud package.
These EXZ files, now unusable with the new Fantom firmware, have a reduced size
compared to those that can be downloaded today through RCM as they contain only
this version with samples encoded at 16 linear bit and therefore not compressed.
With the advent of Zenology, Roland adds two new features: the first is the
insertion of license information (48 Bytes) within the Wave Expansion that make
the EXZ files downloaded from Roland Cloud unique for a handful of bytes and
associated with the account that created them; the second novelty is the
inclusion in these files of the version of the multisamples compressed in the
FCE-DPCM format.
The double format is also present in the “SuperNATURAL Expansion”..
Here is a shot showing, for example, the EXZ009 - EXZ Symphonique Strings
expansion in the version of the Axial site (multisamples in 16 linear bits) and
in the one downloadable with RCM. The compressed part has the same size as the
one present in the old expansions for FA-06/08.
The presence in the EXZ files of multisamples in double
format (compressed and 16 bit linear) and the insertion of the 48 bytes of
license, guarantees Roland a whole series of advantages:
- loading of the versions compressed in Fantom0 (user flash 256 MByte),
AX Edge, RD-88 and JupiterX / XM (they have free flash just over 64 MByte) and
loading of the linear 16 bit versions in Fantom
- loading of the licensed versions (perpetual or subscription) in Zenology
- distinction, thanks to the 48 bytes of license, of the free versions for
Fantom and Fantom0 and the paid ones for AX Edge, JupiterX / XM and RD-88
Regarding the three "SuperNATURAL Expansion" (EXSN01-03) the structure is
identical, with the only difference that,
at least for now, it is possible to use these expansions
only with Fantom and Fantom0
Below are some shots showing the
size of the two versions in the files, the empty space (a series of bytes equal
to zero) and the compression ratio between the compressed version and the linear
16-bit version.
By analyzing the dimensions, the questions posed at the
beginning are clearly answered.
A few brief observations.
The first is that the compressed multisamples present in the
EXZ files all have a size equal to 32 MByte: this is consistent with the fact
that they derive from the SRX expansion cards, all with a maximum capacity of 32
MB and compatible with the old series of Fantom, the XV family (5080, 5050,
3080, 2020) and JV (1080-2080).
The second observation is that the compression ratio of the
FCE-DPCM codec, as seen in the table, is not fixed: this is typical of lossless
codecs and codecs that introduce only small approximations in the compression
phase.
The compression that can be obtained is strictly linked to the characteristic of
the source file.
The last observation concerns the sound quality: how much
does a Fantom0 that reads multisamples compressed with the FCE-DPCM codec sound
“worse” than the Fantom that reads 16-bit linear files (obviously we exclude the
impact of converters)?
I would not assume that for the 15 EXZ, there is a deterioration in quality
because it has to be shown that Roland with Fantom has restarted from the
original uncompressed samples (material from the 90s) and inserted them into the
EXZ directly: it could be that the choice to use linear 16 bit encoding is due
to the Fantom architecture which is very complex as can be seen from the
following diagram and therefore obliges the BMC to work with necessarily
uncompressed samples.
In fact, in Fantom, all the usable
samples (internal, expansions and user) are stored in a 4 GByte eMMC memory and
when switched on they are entirely transferred to RAM (also 4 Gbyte): while the
sounds are synthesized , the necessary data is distributed to the small RAM (32
MB) associated with each of the 4 BMCs, through 2 FPGAs Altera Cyclone V.
AX Edge, JupiterX and presumably Fantom0 instead have a more classic
architecture where the samples always remain in the Flash and are loaded, when
necessary, in the small 32 MByte memory that accompanies each BMC.
Therefore, it cannot be excluded that Roland, for the conversions of the old SRX
cards in EXZ, in Fantom has simply converted the compressed files into 16 linear
bits, obviously without being able to improve their quality, "forced" only by HW
architecture reasons.
Regarding the most recent sounds (see
for example the SN AcPiano2 and the first 4 EXZ expansions that do not derive
from the old SRX cards) certainly the uncompressed nature of the samples
guarantees in Fantom a slightly better quality than that of Fantom0 which is
forced to use the compressed version. The excellent quality of the FCE-DPCM
codec is, however, a guarantee of an almost imperceptible difference.
I conclude with a video I made a few months ago of a
"Teardown" of my Roland AX-Edge with images and hardware details: regarding the
part relating to the sound generation, the mainboard audio contains a single
Roland BMC SoC, 48 MByte of RAM and 256 of flash that contains up to 2 EXZ
expansions and about 150 MByte of firmware and ZenCore samples: in addition
there is a second smaller and slower Flash (48 MByte) probably used for storing
tones and performances.
