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csr-file-structure.md

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File Structure

--- HEADER ---

@ 0x0
  14 bytes
  file signature
  "SP5FPX-130  "

@ 0xc
  2 bytes, little endian
  file size
  appear again @ 0x118
  need to add 0x114 to get the total file size
  0x114 is the size of the header block

@ 0x10
  260 bytes
  all 0's

--- END OF HEADER ---

--- START "CMLF" BLOCK ---

@ 0x114
  4 bytes
  "CMLF"

@ 0x118
  2 bytes, little endian
  size of CMLF block
  need to add 0x114 to get the total file size
  0x114 is the offset of the start of the CMLF block

@ 0x11c
  4 bytes
  "0001"

@ 0x120
  46 bytes
  ???

@ 0x14e
  2 bytes, little endian
  remaining bytes until EOF (starting from 0x14e)

@ 0x150
  20 bytes
  ???
  
@ 0x164
  2 bytes, BIG ENDIAN
  base tone (instrument)
  0x0 - variation grand piano
  0x1 - classic grand piano
  0x2 - modern grand piano (default for PX-130)
  0x400 - elec piano
  ...

@ 0x166
  2 bytes, BIG ENDIAN
  layered tone (instrument)

@ 0x168
  2 bytes
  something with tone layering...
  0x1000 = regular layering?
  0x2000 = bass layering???

@ 0x169
  5 bytes
  ???

@ 0x16e
  1 byte
  something with tone layering...

@ 0x16f
  1 byte
  metronome bpm
  appears again @ 0x198

@ 0x170
  40 bytes
  ???

@ 0x198
  1 byte
  metronome bpm (see @ 0x16f)

@ 0x199
  87 bytes
  ???

@ 0x1f0
  128 bytes
  ???
  it's like each "row" is an addition equation...

@ 0x270
  8 bytes
  ???

@ 0x278
  variable length (3k-1 bytes for k commands)
  recording section

  For PX-130, this block starts with a "start marker" of 36 bytes:
  b"\xf1\x80\x00" * 12

--- START "CMLF" BLOCK ---

--- EOF ---

Recording section

The recording section of the CSR file is a series of

<command + value> (2 bytes)
<delay> (1 bytes)
<command + value> (2 bytes)
<delay> (1 bytes)
.
.
.
<command + value> (2 bytes)

The total size is 3k-1 bytes for k commands.

Delay

The delay is given "ticks", where each tick is 1/96 of a beat. For example, a delay of 1/4 beat will be 24 ticks, or 0x18. The delay is 1 byte, so the maximum delay between commands is 0xff ticks, or 255/96 of a beat. The 0xff command is used to add more dealy.

Commands

The known commands are:

0x15-0x6c = press or release key The command is the key to press or release, where 0x3c is middle C. The value following is the velocity with which the key was pressed, or 0 if the key was released.

0xb1 = press or release damper pedal value = 0x7f for pressing value = 0x0 for releasing

0xf1 = ??? This appears 12 times in a row at the start of the first track, with value 128. It's used by csr2midi as the marker for the start of the recording area.

0xf2 = ??? This appears twice at the start of the first track (after 0xf1), with value 66 and then with value 82.

0xfc = next track The first CSR file starts on the first track (track 0), and each 0xfc command moves to the next track. The value is always 0x0. There is no "previous track" command. The PX-130 has 2 recording tracks, L and R. In the CSR file they are track 0 and track 15. This means that for PX-130 there will be 15 "next track" commands in a row.

0xff = delay Used to extend the delay until the next command. The number of ticks to delay is the value times 0x100. For example, if the value is 2 then need to add a delay of 0x200 = 512 ticks.

Other commands are not known.