View source for BCSTM

[[Category:File formats]]
This document is about the format of CTR Streams (CSTM).

=== Overview ===

The structure is similar to that of a [[BCWAV]], with a few differences, such as its different INFO block format, the addition of a SEEK block, and the organization of the DATA block samples into blocks.

These files are either found in rom:\sound\stream\ or they can be inside of a CSAR.

=== Header ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 4 || Magic (CSTM)
|-
| 0x004 || 2 || Endianness (0xFEFF = little, 0xFFFE = big)
|-
| 0x006 || 2 || Header Size (0x40 due to [[#Info Block|Info Block]] alignment)
|-
| 0x008 || 4 || Version (0x02000000)
|-
| 0x00C || 4 || File Size
|-
| 0x010 || 2 || Number of Blocks (3)
|-
| 0x012 || 2 || Reserved
|-
| 0x014 || 12 || [[#Info Block|Info Block]] [[#Sized Reference|Sized Reference]] (Offset relative to start of file)
|-
| 0x020 || 12 || [[#Seek Block|Seek Block]] [[#Sized Reference|Sized Reference]] (Offset relative to start of file)
|-
| 0x02C || 12 || [[#Data Block|Data Block]] [[#Sized Reference|Sized Reference]] (Offset relative to start of file)
|}

=== Block Header ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 4 || Magic
|-
| 0x004 || 4 || Size
|}

==== Block Types ====

{| class="wikitable" border="1"
|-
! MAGIC !! TYPE
|-
| INFO || [[#Info Block|Info Block]]
|-
| SEEK || [[#Seek Block|Seek Block]]
|-
| DATA || [[#Data Block|Data Block]]
|}

=== Info Block ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 8 || [[#Block Header|Block Header]]
|-
| 0x008 || 8 || [[#Stream Info|Stream Info]] [[#Reference|Reference]] (Offset relative to this field)
|-
| 0x010 || 8 || [[#Track Info|Track Info]] [[#Reference Table|Reference Table]] [[#Reference|Reference]] (Offset relative to [[#Stream Info|Stream Info]] [[#Reference|Reference]] field)
|-
| 0x018 || 8 || [[#Channel Info|Channel Info]] [[#Reference Table|Reference Table]] [[#Reference|Reference]] (Offset relative to [[#Stream Info|Stream Info]] [[#Reference|Reference]] field)
|-
| 0x020 || 56 || [[#Stream Info|Stream Info]]
|-
| 0x058 || X || [[#Track Info|Track Info]] [[#Reference Table|Reference Table]]
|-
| X || X || [[#Channel Info|Channel Info]] [[#Reference Table|Reference Table]]
|-
| X || X || [[#Track Info|Track Info]] Entries
|-
| X || X || [[#Channel Info|Channel Info]] Entries
|}

If encoding is DSP ADPCM:

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| X || X || [[#DSP ADPCM Info|DSP ADPCM Info]] Entries
|}

If encoding is IMA ADPCM:

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| X || X || [[#IMA ADPCM Info|IMA ADPCM Info]] Entries
|}

The info block is aligned to 0x20 bytes.

==== Encoding ====

{| class="wikitable" border="1"
|-
! VALUE !! DESCRIPTION
|-
| 0 || PCM8
|-
| 1 || PCM16
|-
| 2 || DSP ADPCM
|-
| 3 || IMA ADPCM
|}

==== Stream Info ====

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 1 || [[#Encoding|Encoding]]
|-
| 0x001 || 1 || Loop (0 = don't loop, 1 = loop)
|-
| 0x002 || 1 || Channel Count
|-
| 0x003 || 1 || Padding
|-
| 0x004 || 4 || Sample Rate
|-
| 0x008 || 4 || Loop Start Frame
|-
| 0x00C || 4 || Loop End Frame
|-
| 0x010 || 4 || Sample Block Count
|-
| 0x014 || 4 || Sample Block Size
|-
| 0x018 || 4 || Sample Block Sample Count
|-
| 0x01C || 4 || Last Sample Block Size
|-
| 0x020 || 4 || Last Sample Block Sample Count
|-
| 0x024 || 4 || Last Sample Block Padded Size
|-
| 0x028 || 4 || Seek Data Size
|-
| 0x02C || 4 || Seek Interval Sample Count
|-
| 0x030 || 8 || Sample Data [[#Reference|Reference]] (Offset relative to [[#Data Block|Data Block]] Data field)
|}

==== Track Info ====

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 1 || Volume
|-
| 0x001 || 1 || Pan
|-
| 0x002 || 2 || Padding
|-
| 0x004 || 8 || Channel Index [[#Byte Table|Byte Table]] [[#Reference|Reference]] (Offset relative to Volume field)
|-
| 0x00C || X || Channel Index [[#Byte Table|Byte Table]] (Padded to 4 bytes)
|}

===== Byte Table =====

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 4 || Count
|-
| 0x004 || Count || Elements
|}

==== Channel Info ====

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 8 || ADPCM Info [[#Reference|Reference]]  (Offset relative to this field)
|}

===== DSP ADPCM Info =====

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 32 || [[#DSP ADPCM Param|Param]]
|-
| 0x020 || 6 || [[#DSP ADPCM Context|Context]]
|-
| 0x026 || 6 || Loop [[#DSP ADPCM Context|Context]]
|-
| 0x02C || 2 || Padding
|}

====== DSP ADPCM Param ======

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 32 || 16-bit Coefficients
|}

====== DSP ADPCM Context ======

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 1 || 4-bit Predictor + 4-bit Scale
|-
| 0x001 || 1 || Reserved
|-
| 0x002 || 2 || Previous Sample
|-
| 0x004 || 2 || Second Previous Sample
|}

===== IMA ADPCM Info =====

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 4 || [[#IMA ADPCM Context|Context]]
|-
| 0x004 || 4 || Loop [[#IMA ADPCM Context|Context]]
|}

====== IMA ADPCM Context ======

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 2 || Data
|-
| 0x002 || 1 || Table Index
|-
| 0x003 || 1 || Padding
|}

=== Seek Block ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 8 || [[#Block Header|Block Header]]
|-
| 0x008 || [[#Block Header|Block Header]] Size Value - 8 || Data
|}

The seek block is aligned to 0x20 bytes.

=== Data Block ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 8 || [[#Block Header|Block Header]]
|-
| 0x008 || [[#Block Header|Block Header]] Size Value - 8 || Data
|}

The data block is aligned to 0x20 bytes, as well as the data field's actual sample data.

=== Reference Table ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 4 || Count
|-
| 0x004 || Count * 8 || [[#Reference|References]] (Offsets relative to Count field)
|}

=== Sized Reference ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 8 || [[#Reference|Reference]]
|-
| 0x008 || 4 || Size
|}

=== Reference ===

{| class="wikitable" border="1"
|-
! OFFSET !! SIZE !!  DESCRIPTION
|-
| 0x000 || 2 || Type ID
|-
| 0x002 || 2 || Padding
|-
| 0x004 || 4 || Offset ("null" = 0xFFFFFFFF)
|}

==== Reference Types ====

{| class="wikitable" border="1"
|-
! ID !! TYPE
|-
| 0x0100 || [[#Byte Table|Byte Table]]
|-
| 0x0101 || [[#Reference Table|Reference Table]]
|-
| 0x0300 || [[#DSP ADPCM Info|DSP ADPCM Info]]
|-
| 0x0301 || [[#IMA ADPCM Info|IMA ADPCM Info]]
|-
| 0x1F00 || [[#Data_Block|Sample Data]]
|-
| 0x4000 || [[#Info Block|Info Block]]
|-
| 0x4001 || [[#Seek Block|Seek Block]]
|-
| 0x4002 || [[#Data Block|Data Block]]
|-
| 0x4100 || [[#Stream Info|Stream Info]]
|-
| 0x4101 || [[#Track Info|Track Info]]
|-
| 0x4102 || [[#Channel Info|Channel Info]]
|}


==Tools==
The following tools can play BCSTMs and convert them to other formats:
* [https://gota7.github.io/Citric-Composer/ Isabelle Sound Editor]
* vgmstream
* Every File Explorer