ejconlon / polyendtracker-formats

Collaborative documentation of the file formats used by the Polyend Tracker

polyendtracker-formats

Collaborative documentation of the file formats used by the Polyend Tracker

NOTE: This project is not associated with Polyend. This (mis)information is public domain and the authors can't be held responsible for anything, etc...

Status

This document is an incomplete understanding of the pti/mt/mtp file formats as of firmware version 1.6.0.

Questions are marked inline with QUESTION. Please submit PRs to resolve these if you know the answer!

All contributions are welcome.

Related work

Big thanks to @jaap3 and @DataGreed for their awesome work!

• pti-file-format
• polyendtracker-midi-export
• scrapti - [coming back soon]

Overview

The Tracker stores projects in the Projects folder at the root of the SD card. Each subdirectory there represents a single project. (QUESTION: Is there a limit to the number of projects?) The Tracker ignores folder hierarchies here. These project directories can be named according to the regex [[:alnum:]\-+@ ]+. (QUESTION: These are the keyboard keys - is actually more permissive?)

Inside a project folder there is a song file project.mt and two directories, instruments and patterns.

The instruments directory contains pti files that each specify instrument parameters and embed a PCM waveform. These instrument files are named [[:digit:]+ [[:alnum:]\-+@ ]+\.pti, where the digits denote the instrument number.

The patterns directory contains mtp files that specify pattern contents. These pattern files are named pattern_0?[[:digit:]]+.mtp, where the digits denote the pattern number.

The words in these formats are in little-endian order. Each format is framed with a file-type code and a 4 byte CRC32 code. The CRC is at the end of any fixed-length content (which means that it appears between the header and the sample data in a pti file).

*.mt song files

• Code MT at byte 0
• Fixed length of 1796 bytes
• CRC32 code of all preceding data at byte 1792

TODO - Summarize information from polyendtracker-midi-export project

DataGreed has an excellent diagram. His parser is also a good resource.

*.mtp pattern files

• Code KS as byte 0
• Fixed length of 6184 bytes
• CRC32 code of all preceding data at byte 6180

TODO - Summarize information from polyendtracker-midi-export project

Again, DataGreed has a parser for this.

*.pti instrument files

• Code TI as byte 0
• Dynamic length - header followed by sample data
• Fixed length header of 392 bytes
• CRC32 code of all preceding header data at byte 388
• Sample data as 16-bit Mono PCM waveform (sequence of Int16s) after CRC until end of file

NOTE In some cases the sample count header field is 0, but sample data is still present.

TODO - Summarize information from pti-file-format project

jaap3 has a great table of all of the fields.

Known changes from firmware version 1.5 to 1.6

• mt files increased in size
• Some unknown preamble changed in the pti header (probably version).