Sustainability of Digital Formats: Planning for Library of Congress Collections

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Downloadable Sounds Format, Version 1.1b

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name Downloadable Sounds Format

Format usually associated with MIDI data that features segments of waveform audio and "articulation parameters." This description is about the format specified as version 1.1b (2004), a trivial revision of version 1.1a (1999). The specification defines what are called "levels," with the functionality of Level 1.1 (the aforementioned specifications) being surpassed by later versions like Levels 2.1 (2000-01) and 2.2 (2006). The specification states that waveform-articulation pairs are "needed to create one or more 'instruments,'" i.e., each pair provides data that supports the production of sounds (p.35). The waveform elements consist of 8- or 16-bit PCM samples, described as "WAVE format," apparently meaning structured as if in a WAVE-LPCM file (pp. 63-5).

The difference between version 1.1a and 1.1b is described as follows in the preface to 1.1b: "Version 1.1b contains only one change from 1.1.a, which is the removal of “Expression” from the list of controllers that are not reset when RAC = “0”. This is an editorial correction, since all known implementations already worked this way." The additional changes made in later versions of the specification are outlined on the MIDI DownLoadable Sounds page ( This link no longer worked when checked in July 2021, and the above information may no longer be available on the website. The webpage containing the DownLoadable Sounds specifications is

Production phase May be used by composers or arrangers for initial-state activities, in middle-state exchange of data or archiving, or for final-state, end-user delivery.
Relationship to other formats
    Subtype of RIFF, Resource Interchange File Format for Windows 3.1
    Has earlier version DLS Level 1 Specification, Version 1.1a (January 1999), not documented at this Web site.
    Has extension DLS Level 1 Specification, Version 2.1 (January 2000), not documented at this Web site. Since the publication date precedes that for version 1.1b, this version is classified as an extension.
    Has extension DLS Level 2 Specification, Version 2.2 (April 2006), not documented at this Web site.
    Used by XMF_1_0, XMF, eXtensible Music File Format, Version 1.0
    Used by RMID, RIFF-based MIDI File Format
    Used by Other file or wrapper formats, not documented at this time

Local use Explanation of format description terms

LC experience or existing holdings None
LC preference None established at this time.

Sustainability factors Explanation of format description terms

Disclosure Fully documented. Developed by the MIDI Manufacturers Association (MMA;
    Documentation The specifications for Downloadable Sounds Level 1, Version 1.1b (2004) and and Level 2 are available from the Midi Association's DownLoadable Sounds page.
Adoption Not known to the compiler of this document.
    Licensing and patents None.
Transparency Relatively transparent, including the included waveform data. See also RIFF and WAVE-PCM.
Self-documentation See RIFF.
External dependencies Playback requires sequencers and/or synthesizers (which may be in software or hardware) to produce the actual sound.
Technical protection considerations None

Quality and functionality factors Explanation of format description terms

Normal rendering See external dependencies, above.
Fidelity (high audio resolution) Not applicable; fidelity depends upon the performance of external hardware and software.
Multiple channels Not inherent to this format. DLS works with MIDI, which features as many as 16 channels.
Support for user-defined sounds, samples, and patches DLS is a downloadable sound element for use in MIDI and [possibly] other contexts.
Functionality beyond normal rendering Not investigated at this time.

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension dls
From The File Extension Source. In 2004, this source added this note: "Interactive Music Architecture. A Roland GS MIDI sound set file. This format has been licensed by Microsoft and Apple for use in their products."
Internet Media Type Not found.  Comments welcome.  No Internet Media Type listing found at
Magic numbers Hex: 52 49 46 46
From The File Extension Source; the magic numbers for all RIFF subtypes begin with this string.
RIFF form type DLS

Notes Explanation of format description terms


From the specification for Version 1.1b: "Downloadable sound collections are stored in a RIFF file with a form type of 'DLS'. The subchunks . . . are the 'vers', 'dlid', 'colh', 'ptbl', and 'LIST' chunks. There are three top-level LIST chunks: the <INFO-list> chunk contains textual informative details about the instrument collection, the <lins-list> instrument list chunk contains <ins-list> instrument subchunks, and <wvpl-list> wave pool chunk contains <wave-list> subchunks (similar to wave files). The optional top-level <dlid-list> chunk specifies a globally unique identifier for the entire collection. The <colh-list> chunk defines the number of instruments in the collection. The optional <vers-ck> chunk specifies the version of the file. The <ptbl-ck> chunk contains a list of reference entries to digital audio data. The <ins-list> subchunks within the <lins-list> chunk are the actual instruments stored in this collection. Additional <dlid-ck> chunks may be used to specify globally unique identifiers for each <ins-list> instrument and <wave-list> wave file chunk." (p. 36)

DLS "enables the author to completely define an instrument by combining a recorded waveform with articulation information. An instrument defined this way can be downloaded into any hardware device that supports the standard and then played like any standard MIDI synthesizer. Together with MIDI, it delivers . . . . a common playback experience, unlike GM [General MIDI]; an unlimited sound palette for both instruments and sound effects, unlike GM; true audio interactivity, unlike digital audio . . . ." (p. 1)

From an article by Jennifer Hruska: "So what do you do when you've tired of your sound card's ROM presets or you can't stomach another General MIDI violin? You might find the answer in downloadable sounds. These give you access to hundreds or even thousands of new sounds that you can use in your sound card, in a hardware sampler, or even in a software sampler running on your computer. Unlike with most sound-card presets, you can tweak, twist, and fine-tune downloadable sounds to your liking." (This article was no longer available when checked in July 2021, and the link now redirects to


The specification reports that DLS was developed in the early 1990s under the auspices of the Interactive Audio Special Interest Group's Downloadable Sounds Working Group (IASIG DSWG), who sometimes met as the Downloadable Sounds Device Architecture Working Group (DSDAWG) and the Downloadable Sounds API and File Format Working Group (DSAFFWG).

Meanwhile, until the Sonic Spot website was abandoned around 2013, an undated note at reported: "The Downloadable Sounds Format (DLS) is closely related to the [E-mu Systems] Sound Font format." And: "E-mu Systems' Sound Font format (SF2) is relatively new, but is quickly becoming the most widely supported patch file format. The original SoundFont Bank 1.0 format (SBK) was supported by the Create Labs Sound Blaster AWE32 which had the EMU8000 wavetable synthesizer (by E-mu Systems). It then was improved and the specification was made available to the public allowing software developers to more easily support this format. This format is currently being pushed by E-mu and Creative Labs in hopes of gaining even more support with free sound font give-aways and other promotional activities."

Format specifications Explanation of format description terms

Useful references


Last Updated: 08/10/2021