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Sound font 2 parsing library and utilities

Project description

Sf2Utils is a soundfont 2 parsing library and companion utility. It is meant for developers aiming to use soundfont 2 file as input, typically for converting to another format.

Installation

Sf2Utils is installable from PyPI with a single pip command:

pip install sf2utils

Alternatively, Sf2utils can be run directly from sources after a git pull:

git clone https://gitlab.com/zeograd/sf2utils.git
cd sf2utils && python setup.py install

Companion script

sf2parse is a command line utility used to parse a sound font 2 file. It is meant as debug companion for the sf2utils parser library as it shows what is understood from its parser.

usage: sf2parse [-h] [-d] sf2_filename

LGPL v3+ 2016-2017 Olivier Jolly

positional arguments:
  sf2_filename  input file in SoundFont2 format

optional arguments:
  -h, --help    show this help message and exit
  -d, --debug   debug parsing [default: False]

Parse sf2 file and display info about it

Library use

sf2utils can be used as a library for parsing SoundFont2 files. There are 2 API levels, a low level and high level one. They both open SoundFont2 file the same way:

from sf2utils.sf2parse import Sf2File
with open('file.sf2', 'rb') as as sf2_file:
    sf2 = Sf2File(sf2_file)

Note that opening the file is up to the library user because samples data are lazy loaded. Accessing sample data will seek and read data. You shouldn’t access sample data outside of the content in which the file is opened, as it will fail.

Low level library API

Once sf2 is a valid Sf2File, all metadata are available via the property raw, which has fields for the various sections in a SoundFont2 file.

  • sf2.raw.info is a dictionary with all info in the info block of the SoundFont2 file with keys as binary strings.
  • sf2.raw.smpl_offset is the offset in the original file where the sample data are located.
  • sf2.raw.sm24_offset is the offset in the original file where the complementary 8bits of sample data are located.
  • sf2.raw.pdta is the main metadata structure, a dictionary with tuples named after the specification and indexed using specification structure names :
    • Pbag -> ‘gen’, ‘mod’
    • Igen -> ‘oper’, ‘amount’
    • Imod -> ‘src_oper’, ‘dest_oper’, ‘amount’, ‘amount_src_oper’, ‘trans_oper’
    • Pmod -> ‘src_oper’, ‘dest_oper’, ‘amount’, ‘amount_src_oper’, ‘trans_oper’
    • Pgen -> ‘oper’, ‘amount’
    • Shdr -> ‘sample_name’, ‘start’, ‘end’, ‘start_loop’, ‘end_loop’, ‘sample_rate’, ‘original_pitch’, ‘pitch_correction’, ‘sample_link’, ‘sample_type’
    • Phdr -> ‘name’, ‘preset’, ‘bank’, ‘bag’, ‘library’, ‘genre’, ‘morphology’
    • Ibag -> ‘gen’, ‘mod’
    • Inst -> ‘name’, ‘bag’

With this API, field interpretation remains up to the library user.

High level library API

With this API, info are available via the info property, which is a pretty printable tuple where every field comes from the info block in the SoundFont2 file.

Samples are accessible via the samples property, which is a list of Sf2Sample from which you can retrieve loop information and raw data.

Presets are in the presets property, which is a list of Sf2Preset from which you can list generators, modulators, instruments and bags.

Instruments are in the instruments property, which is a list of Sf2Instrument from which you can list bags of generators, modulators.

Bags are of class Sf2Bag and offer a wide range of property returning various high level info (about loop, tuning, filters, envelopes, instruments, samples, …) or None when no generator was found.

All those classes have a pretty_print returning a pretty printed string, recursing over subelements.

Project details


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