Audio documents in the collections of memory institutions in context of long term preservation in Czech Republic. Feasibility study by National Library of Czech Republic about the possibility of long term preservation of digitized itemsi

Keywords: audio documents, digital preservation, long term preservation, digital formats, metadata

Mgr. Natalie Ostráková , Filip Šír, Dis. / Národní knihovna České republiky (The National Library of Czech Republic), Klementinum 190, 110 00 Praha 1, Česká republika, Národní muzeum (National Museum),Václavské nám. 68, 115 79 Praha 1, Česká republika

The National Library of Czech Republic (NK ČR) has a long-term digital repository for some years now – however this repository gathers digitalized periodicals and monographic documents only. In terms of advancing and developing its solutions for long-term preservation the NK ČR has launched cooperation with the Moravian National Library to also include the audio documents regarding long-term preservation. This article represents an initial analysis that was conducted to enable the creation of a standard for long-term reposition and access for audio documents. This analysis examines three areas – folder formats, metadata and tools for audio documents. The subject of the analysis is the examination of the current steps and initiatives of the selected memory institutions with regard to the long-term preservation and access of audio documents (recommended formats, metadata scheme and tools). The resulting outcome of the analysis shall be the methods utilized to define the national standard in terms of reposition and access of audio documents for Czech memory institutions. The archive package specification (AIP, Archival Information Package),in accordance with proven international standards, shall be the keystone of the audio documents standard. The next subsequent step will be the creation of SIP package specification (Submission Information Package) for data contributors. The SIP package specification for data contributors will enable the digitalization standardization of audio documents regarding their long-term preservation which will make it easier to transfer them into the AIP package in the NK ČR long-term repository.

Current situation of audio documents preservation in the Czech Republic

Prior to the introduction of the analysis it is necessary to describe the current situation of the memory institutions, or more precisely of the libraries in the Czech Republic, and their current state.

The National Audio Archive (an institution administering and handling audio documents as well as policy-setting role) does not exist in the Czech Republic. This is a given fact and must be factored in the decision-making process. Whereas in other countries sound recordings libraries - e.g. British Libraryⁱⁱ, Library of Congressⁱⁱⁱ, Bibliothèque nationale de France^iv - archives etc. are common, in the Czech Republic this has so far been an unattainable goal both for the past generations and for the current one. The non-existence of a national audio archive has a negative impact that influences various aspects. For example, it leads to the fact that institutions do not handle them in a way that would allow record-keeping, protection, digitalization and primarily access i.e. preservation for future generations. Another aspect is that audio documents, representing a smaller part of the heterogenous stock of libraries, archives, or museums, have not been a priority. They represent second-tier interest behind printed documents. It also must be noted that audio stocks have not been conceptually and reliably mapped, or more precisely organized, and therefore cannot be accessed. This has a negative impact on other processes which should lead to a conceptual solution in terms of digitalization itself, i.e. long-term preservation of audio documents. This is further enhanced by the fact that the abovementioned processes – cataloging, digitalization, access – are more sophisticated and therefore more challenging than those related to text and image processes (Horová, Novotná, Šír, 2016). The solution at hand is to assign one of the institution, set up by the Ministry of Culture of the Czech Republic (MK ČR), the task to begin conceptual coordination of the described processes, namely to methodologically guide the respective institutions and individuals step by step to successful fulfilment of the three key processes – record-keeping, digitalization, access.

The Moravian Library (MZK) in Brno has been assigned the methodological and coordination role by the MK ČR in 2015 regarding audio documents and Virtual National Sound Recordings Library development (Rozhodnutí ministra kultury, 2015). This is already reflected in the MZK Policy 2015-2020: “The Moravian Library in Brno will organize and coordinate the cooperation of respectable institutions and organizations that preserve the cultural audio heritage material with the aim to methodologically support cataloguing and digitalization of audio records in the Czech Republic and to create a Virtual National Audio Recordings Library as a gateway, allowing access to audio documents information and as a foundation-setting tool allowing for subsequent digitalization.“ (Koncepce Moravské zemské knihovny, 2015). Therefore, there is a dedicated institution in the Czech Republic with the mission to coordinate and methodologically facilitate concrete steps in the whole process of protection and accessibility of audio documents.

To grasp the wide complexity pertaining to these processes it is necessary to bear in mind certain key principles related to audio and audiovisual document preservation. It is essential to point out technical digitalization standards of ARSC (Association for Recorded Sound Collections)^v or IASA (International Association of Sound and Audiovisual Archives)^vi which will be analyzed in detail in the following chapters. But most of all, it is crucial to analyze the document that should spearhead the realization of numerous projects, change the attitude of collection owners, or bolster the efforts of National Library of the Czech Republic and other memory institutions as well. Vancouver Declaration – international UNESCO/UBC document originated as a result of The Memory of the World in the Digital Age: Digitalization and Preservation conference – states that:

In the modern age digital information are dwindling due to the fact that its values are underestimated, based on the lack of legal and institutional frameworks, or because curators do not have the knowledge, skills, or financial means.

If we closely look at this sentence it becomes obvious that it is necessary to initiate conceptual work and to begin educating not only curators, librarians, museologists but also key management personnel administering these collections. Regarding audio documents, it is pertinent to understand all the aspects related to digitalization, but also to present a drafted solution for adequate description of all the metadata types. The results of this 2012 international conference are well known. Nevertheless, it is necessary to mention the key pillars that must be considered and applied regarding all ongoing or future projects taking place at various memory institutions in CZ. More than 500 members agreed that:

2. digitalization can protect precious analog documents from devaluation by minimizing manipulation. In the case of audiovisual documents, digitalization is the only measure how to ensure their survival and preservation;

However, this means that such applicable guidelines must be in place that will be applicable to all various institutions or can be used to educate information staff and specialists dealing with these documents.

6. educational programs for information professionals must be created and accessible to them in order to allow preparation and re-education for the purposes of digitalization process initiation and preservation of relevant materials, satisfying the needs of the various governments and their citizens.

Moravia Library in Brno - Audio documents incorporated in strategic and conceptual documents

The issue of audio documents represented a neglected part of our cultural heritage until 2015: it was not represented in any national strategic document nor was it conceptually deliberated at any of the national institutions. Only thanks to the active support of the Moravian Library in Brno, in the form of joining the international association IASA and opening the topic at the Central Librarian Council, was it possible to insert a separate chapter dealing with the issue into the National Cultural Implementation Plan 2015-2020 - – “3.3.2 Preservation of the national audio heritage “(Plán implementace Státní kulturní politiky, 2015, p. 47–48). A separate chapter containing the below-mentioned points is crucial in relation to this study and subsequent long-term preservation efforts:

„3.3.2 Preservation of national audio heritage

3.3.2.A: The protection and accessibility concept of audio documents as a significant part of the cultural heritage

3.3.2.B: The set-up of a methodological and digitalization center for audio preservation documents located at the Moravian Library in Brno in cooperation with National Museum (Czech Music Museum)

3.3.2.C: To ensure the creation of long-term repository for archival and access purposes for audio data in terms of LTP system at the Ministry of Culture

3.3.2.D: To operate and develop the Virtual National Recordings Library portal (role of the sector aggregator) ^vii“

It is well shown in 3.3.2.B and 3.3.2.C that methodology and digitalization is well anchored and dealt with. However, long-term repository – a crucial component as well- is described as well.

Long-term archival formats for audio documents

Data are stored on computers in a respective file format that determines its inner structure, rules, and procedures for their utilization. The respective formats differ in terms of compression, error resilience, existence, availability, and specification openness (e.g. standard), distribution among users etc. A wide variety of audio documents storage formats are in existence, however only some are appropriate for the memory institutions. Special attention must be paid to the choice of archival format (long-term reposition format). This format should ideally meet the following rules (Library of Congress, 2013; Rog, Wijk 2008):

1. open source format with publicly available and descriptive specification,

2. widely spread so that it is supported in the future and so that tools for its migration and validation are in place,

3. transparency – straightforward structure and the possibility to be analyzed by existing tools (i.e. not cyphered and ideally not compressed),

4. self-descriptive – i.e. the ability to insert metadata directly into the digital object (descriptive, technical…), easier object management,

5. robust, i.e. error resilience,

6. hardware, operational system, software independence.

The above-mentioned description for audio documents archival format is best met by audio signal coded by the pulse coded modulation (PCM) and by container formats WAVE^viii, BWF^ix, AIFF^x. The PCM is a method designed for analog- digital audio signal transfer. The key coding parameters are the sampling frequency and bit depth. These parameters effect the authenticity of the recorded sound (i.e. the resulting sound quality). These values are currently recommended for long-term preservation: 24bit (and greater) depth and so-called sampling frequency of at least 48 kHz, ideally 96 kHz and higher. (International Association of Sound and Audiovisual Archives, 2009; Brylawski, 2015). These values ,well above human hearing capacity, enable information storage that cannot be detected by human ear, however the audio document stores them^xi (CDP Digital audio working group, 2006). These higher values should also enable the listeners to perceive the space, depth, and other sound qualities better. (Consortium of Academic and Research Libraries in Illinois, 2014).

However, in certain cases lower values are permissible, such as:

1. Medium CD, DAT^xii etc., which entail 44,1 kHz and 16bit audio data values. 96/24 value digitalization would not have impact on the resulting audio quality and would only enlarge the file.

2. Certain sources state that lower sampling frequency^xiii is sufficient for spoken words. Consortium of Academic and Research Libraries in Illinois recommends the 48 kHz frequency for spoken word digitalization - without background music or other e.g. animal background sounds (Consortium of Academic and Research Libraries in Illinois, 2014).

The established practices of the relevant institutions may wary. For example, audiocassettes and tapes digitalized at the J. Willard Marriot Library in Utah use 44,1 kHz sampling frequency and 24 bit depth (J. Willard Marriot Library, 2015). Higher values are preferred at the University Library in York – ideally 32 bit depth (24 minimum) and sampling frequency of 96 kHz (48 kHz minimum) (York, University Libraries, 201?).

WAVE, BWF and AIFF formats are container formats which means that they can carry other objects such as metadata. Audio data coded via the PCM^xiv are most commonly carried by these containers (Florida center for library automation, c2008).

WAVE format (Waveform Audio File Format) was created in 1991 by Microsoft and IBM. It has a simple structure and is one of the simplest formats for audio storage (Remo Software, 2015), which makes it suitable for long-term storage. Also, it is compatible with Windows, OS X and Linux operational systems. The format is widely used in the music and broadcasting industry, which results in high application and hardware support. Therefore, future support of the format is likely.

By modifying the WAVE format (adding a separate space specifically for metadata entry) the European Broadcasting Union has created the BWF (Broadcast Wave Format) format in 1997. This format became the standard for broadcasting institutions and its use is considered as a ´bulletproof´ procedure for digital audio storage (Whibley, 2016). It is open-source, widely spread, transparent, self documenting, independent of any hardware and software and is not limited by any patents.

In 2008 Florida Voices initiative, as part of Florida Center for Library Automation, stated that WAVE and BWF formats are the most widely utilized formats in the United States of America (Florida center for library automation, 2008). It is apparent that the situation is the same in 2016 – WAVE and BWF formats are the most widely spread formats for long-term repository according to the Digital Preservation Team at the British Library (Whibley, 2016). BWF format is also recommended by three significant organizations – International Association of Sound and Audiovisual Archives (IASA) (International Association of Sound and Audiovisual Archives, 2009), Library of Congress (Library of Congress, 2016) and the ARSC association (Association for Recorded Sound Collections) (Brylawski, 2015). Recommendations presented by the IASA in its publication “TC-04 Guidelines on the Production and Preservation of Digital Audio Objects “(International Association of Sound and Audiovisual Archives, 2009) seem to be the most utilized in terms of long-term audio documents storage. WAVE and BWF ,serving as archival formats, are currently accepted and recommended for example by: British Library, British Broadcasting Corporation (BBC) (Whibley, 2016), Moravia National Library (Šír, Žabička, 2013), Library and Archives Canada, 2015^xv, DataShare digital repository at University of Edinburgh^xvi, Colorado State University digital repository (Colorado State University, 2015) (however WAVE is preferred)^xvii, J. Willard Marriott Library at Utah University^xviii, University of Minnesota institutional repository^xix (University of Minnesota, c2014) etc.

AIFF format developed by Apple Computers in 1988 is widely spread among the Macintosh computer users, however it is not as staunchly supported as the WAVE format. Most OS Windows users utilize WAVE. (Library of Congress, 2014) The AIFF format is represented less in the format guidelines of the various memory institutions than WAVE ^xx (Rimkus et al., 2014). The AIFF is cited as a preferred format (along with WAVE) by the State Library New South Wales (State Library New South Wales, 2015).

Audio data can be compressed, with no incurred loss, in case the organization is limited by its storage capacity. The no-loss FLAC format/codec can be used. The FLAC codec compresses audio data without any loss and the resulting sound has the same quality as WAVE format during sound quality tests. WAVE and BWF format conversion into FLAC format is hypothetically reversible, without losses, at any time. (Xiph.org Foundation,2014) The FLAC format has certain advantages in comparison to BFW and WAVE. It can reduce file size up to two thirds of its original size. In addition, every FLAC file has a BWF/WAVE original file control total-sum mechanism (algorithm MD5) in its file heading, which allows easier data integration control. This control is not then dependent on external file with control total-sum mechanisms. (Rice, 2013)

The FLAC format along with BWF is the preferred archival format of the U.S. National Archives and Records Administration that keeps and safeguards US government and historical records (The U.S. National Archives and Records Administration, 2014). Other organizations such as Bentley historical Library (Bentley historical Library, 2016), University of Edinburgh DataShare digital repository (University of Edinburgh, 2015), York University Libraries (York University Libraries, 2015), UK Data Archive (UK Data Archive, 2016), Tasmanian Archive and Heritage Office (Tasmanian Archive and Heritage Office, 2015), Binghampton University Libraries (Binghampton University Libraries, c2016) accept and recommend the FLAC format alongside WAVE, BWF and/or AIFF. BBC uses the WAVE format for larger files but do not exclude the use of FLAC format (Whibley, 2016). National Archives of Australia are now considering FLAC format as its second archival format^xxi which will serve as a normalization medium for input formats (Crowe, 2016). The Dutch National Library is now deciding between WAVE and FLAC formats (Knijff, 2017).

Formats designed for audio documents accessibility

Access formats are not subject to such high standards as long-term repository formats. Compressed formats are used (for the purposes of accessibility) which enable multiple reduction in size, compared to the original file, and therefore allow for a smoother and faster transfer via network/local network. The selection process of the given format is influenced by the format compression efficiency and depends on the community user-friendly interface (i.e. browser support, app support etc.). MP3 and AAC, belonging to the MPEG segment, are suitable formats.

MP3 – or namely the MPEG-1 or MPEG-2 Audio Layer III – is one of the most widespread compressed formats today. It is used for audio documents transfer via the internet and for music players. Transfer speed that codes the file is set during the coding process (bitrate). This allows to manage and influence the resulting file size and sound quality. The higher the bitrate, the bigger the resulting size and the higher sound quality. The 128 kbps bitrate for monophony sound and 256 kbps bitrate for stereophonic sound are most common bitrates. However, some organizations choose higher bitrate to achieve higher sound quality. For example, Stanford University utilizes MP3 files with 160 kbps bitrate (mono) and 320 kbps bitrate (stereo) (Stanford University, 201?).

The AAC (Advanced Audio Coding) is the newest MPEG standard, allowing broader sampling frequency, bitrate scope and supports more channels than MP3. In addition, it has a more efficient compression than MP3 – it achieves higher quality sound at same compressed file size. In comparison to MP3 it also has at least one disadvantage. Both standards have patent protection, however software licenses for AAC are more expensive and patent owners are allegedly more diligent in license policy supervision (Fries, c2005). The AAC access format is currently used by Indiana University (Hardesty, 2016). Since 2003 this format is used by Apple Computers for online music sales purposes (Truesdell, 2007 s. 516).

There are other available formats that have a more efficient compression and are not patent protected (WMA, Ogg Vorbis etc.), however lack widespread dissemination. Fries (c2005, s. 210) states that MP3 has become the so-called format wars winner. It is based on an open-source standard that has been made available to hardware and software developers sooner then another format documentation. This format became quickly supported by a whole-range of devices, and users became accustomed to it. MP3 sound quality is sufficient and storage capacity prices are plummeting.

The WAVE and BWF formats (long-term repository) along with the MP3 format (access) are the front-runner candidates for the National Library of Czech Republic. The above-mentioned chapters of this analysis prove that the respective formats are the most widely used ones. Other sound formats such as FLAC, AAC or Ogg Vorbis will be continuously monitored and evaluated by the NK ČR. Audiovisual archivist Dave Rice comments on the continuous BWF/WAVE format supremacy – the current best practices do not have to correspond to the actual state of the technological progress, therefore instead of using the term “best practices” he uses “good-enough-for now practices “(Rice, 2013).

Metadata

It is essential to incorporate metadata into the digital files i.e. with descriptive information such as origin, traits, structure, integrity, rules of conduct, intellectual property rights and accompanying restriction etc., for the purposes of access and long-term repository. It is possible to divide metadata into three categories: descriptive metadata, administrative metadata and structural metadata (Lazinger, 2001). It is suitable to ensure metadata entry based on metadata schemes (standards), which determine usable elements (metadata units) and rules for record/entry (Caplan, 2003, s. 5). Utilization of these standards enables smoother data systems transfer, their conversion, and efficient metadata creation.

Descriptive metadata describe and identify information sources, and are a crucial component in terms of searching activities. A variety of metadata schemes for descriptive metadata are in existence – universal descriptive schemes for various document description along with schemes designed for audio and audiovisual documents. It is possible to utilize the universal Dublin Core^xxii scheme that is simple yet efficient, and allows the description of a wide variety of objects – ranging from classical printed documents (books, magazines etc.) to web pages, audio documents and 3D objects. However, in certain cases the Dublin Core is too brief. The IASA recommends supplementing the Dublin Core scheme or to replace it entirely with MODS^xxiii (International Association of Sound and Audiovisual Archives, 2009, s. 24) metadata scheme. The MODS scheme allows for a more detailed object description than Dublin Core, in addition with multi-layer description (collection, vinyl record side, trail) and can be used for description of various documents (like Dublin Core).

Further, it is possible to use PBCore^xxiv metadata scheme for audio documents description. This scheme was specifically designed for audio/audiovisual documents description, allowing for better illustration of specifics of these documents. ^xxv This scheme was primarily designed for broadcasting and television stations. Today, the American Archive of Public Broadcasting organization is managing the PBCore scheme – using it for its document description since 2013. PBCore is based on the Dublin Core scheme and is expressed in XML language. (Brylawski, 2015, s. 84). Should the need for a more detailed description arise, than other XML schemes can be incorporated into PBCore – such as PREMIS^xxvi and AES57^xxvii schemes. The main advantage of PBCore is its simplicity and transparency for anyone who has little or no metadata experience at all. It is sufficiently complex for the broadcasting and television stations. The memory institutions do not currently widely use this scheme.

The combination of Dublin Core and MODS schemes is currently part of the metadata specification for visual data at the National Digital Library (NDK), and will probably be used for audio documents storage as well – as recommended by the IASA directive (International Association of Sound and Audiovisual Archives, 2009). These descriptive schemes are seemingly the most utilized ones at the various memory institutions, which will allow for possible future systems swap and another format conversion. MODS scheme is sufficiently complex and the Dublin Core scheme will likely have a robust support in various software systems. The other reason for this decision is the catalog practice. When digital documents are already inscribed in MARC format in the library systems, then it is easier to transfer these into MODS scheme rather than into PBCore scheme.

Administrative metadata serve to allow for digital data management. They contain data origin information, their digital lifecycle, rights, technical document properties etc. Further, it is possible to divide the administrative metadata into technical metadata, archival metadata and metadata describing intellectual property rights.

Technical metadata contain information reflecting on the technical properties of the respective digital objects, software and hardware environment in which they were created or adjusted etc. This set of information then allows for document search, based on their technical properties. Should a discrepancy between these properties and current practice occur, then protective measures are undertaken (e.g. obsolete format migration and update) (Hutař, 2012, p. 80-81).

In terms of audio documents technical metadata record entry, a set of metadata standards can be used, that were specifically created for audio documents. AudioMD metadata scheme, created by the Congress Library in 2001-2003, is one of them. It was originally intended only for temporary use. Until 2011, when a new scheme was releases, the AudioMD scheme was allegedly the best scheme regarding technical properties description (DeRidder, 2015). Today this scheme is used for example by the National Digital Library of Finland (Kansallinen digitaalinen kirjasto, 2016) and by the University of Texas Libraries (University of Texas Libraries, 2012; Cofield, 2016). University of Texas Libraries are ready to evaluate scheme AES57. (Cofield, 2016)

In 2011 Audio Engineering Society (AES) organization issued AES57 metadata standard, which should replace the AudioMD scheme in the upcoming years (Technical metadata, c2016). This scheme allows for a detailed digital object and original source description (from all the presented technical schemes this one enables the most detailed document description). AES57 scheme is being used by e.g. Harvard University and University of Alabama Libraries (DeRidder, 2015).

PBCore metadata scheme can encapsulate digital audio technical capabilities as well. In comparison to AES57 and AudioMD, it is easier to understand, but it is less detailed and structured. Therefore, it would be suitable to add the AES57 scheme.

The future of the AudioMD scheme seems uncertain. This is underlined and illustrated by the fact that AudioMD scheme is absent from the ARSC organization guideline, jointly collaborated with the Library of Congress^xxviii. This technical metadata guideline presents only AES57 and PBCore schemes. PBCore scheme does not allow for a sufficiently detailed technical description. At the moment the AES57 metadata scheme seems to be the most suitable scheme for metadata description – broad and robust, fulfilling the National Digital Library current practice of maximum information storage.

Technical metadata will be partially filled by the JHOVE or FITS metadata extractors.

The archival metadata contain information necessary for long-term document storage. Their goal is to support the future longevity, usage, authenticity, and comprehensibility. (PREMIS Editorial Committee, 2015, p. 1) They represent information documenting the circumstances of the creation of such document, information regarding undertaken action with relation to stored files, and internal and external relationship between objects´ information metadata etc. The National Digital Library uses the PREMIS metadata scheme in terms of visual documents archival metadata entry. This scheme will also be used for audio documents and will be expanded with additional necessary features. This is because audio documents do not have a scheme at the moment, that would allow metadata entry related to digital audio document origin^xxix. This entails information pertaining to used devices (scanner, player, preamplifier…) and their configuration. ^xxx

Digital objects are often composed of multiple same-type/different type files – multiple audio file versions, metadata, visual data (e.g. cover, record, booklet) etc. Structural metadata illustrate the relationship and interconvertibility of each of the objects, and as such allow for a meaningful document illustration. METS scheme and its structural maps can be used to express the document structure – and probably will be used for the audio documents as well. METS scheme will also be used as a metadata scheme container for selected metadata due to transparency and simplicity purposes.

Visual documents, accompanying audio documents and their metadata, will be part of the stored data – e.g. cover, booklet, picture of the physical music document (vinyl record etc.). These visual data will be created according to the current visual data specifications inscribed in the National Digital Library project. Images will be in JPEG2000 format and most likely in two versions (archival and quality access). MIX standard will be used for their technical properties description.

File format validation and technical metadata extraction

The decision regarding the file archival format is influenced by the existence of tools that can identify, validate, and characterize it. Several tools have been tested. DROID^xxxi, Siegfried^xxxii and FIDO^xxxiii tools were tested in relation to the identification process. All three use the PRONOM^xxxiv register for identification. The FIDO tool did not recognize one of the WAV subversions (i.e. marked it as other version), therefore we do not consider its use in our processes. DROID and Siegfried tools matched in all cases – one of them will likely be chosen for identification purposes^xxxv.

JHOVE^xxxvi tool can be used for validation – its WAVE-hul module recognizes BWF and WAVE formats and their individual versions (WAVEFORMATEX, PCMWAVEFORMATEX etc.).

A slew of tools exists for metadata extraction. JHOVE, MediaInfo^xxxvii, FITS^xxxviii, Apache Tika^xxxix, Exiftool^xl and fairly new PET^xli tool were tested. JHOVE exhibited the best results with detailed and precise^xlii properties listing. Compared to other tools, it also provides a validation result report (along with extracted metadata). FITS tool, containing DROID, JHOVE and MediaInfo, can be used as well. It has been found during the study that e.g. University of Alabama uses FITS for validation, characterization, and identification. AES57 scheme has been mapped on its outputs and now they can automatically fill technical metadata and identify and validate the format at the same time. (DeRidder, 2015)

Conclusion

As well as printed documents, audio documents are an integral historical part of any country, mapping and documenting its development. The protection and preservation of these documents has been a worldwide topic over the last 10 years. Foreign experience and methods accumulated over this period can serve as an invaluable source of information. Selective stock-taking is currently taking place in the Czech Republic and it is expected that digitalization will commence soon. Therefore, our audio cultural heritage will be available to users (to a certain extent) in the near term and preserved for future generations. The preparation of archival standard, as well as long-term protection formats, is a necessary component on this endeavor. This study summarized the utilized archival and access standards (for data formats and for metadata as well) and proposes suitable next steps in terms of spearheading a preparation of a national standard, based on methods and practices used and adopted by the global community.

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ⁱ Made possible thanks to institutional research conducted by the National Library of the Czech Republic financed by the Ministry of Culture of the Czech Republic in accord with the Long-term Conceptual Development of Research Organizations.

ⁱⁱ http://sounds.bl.uk/

ⁱⁱⁱ http://www.loc.gov/jukebox/

^iv http://gallica.bnf.fr/

^v http://www.arsc-audio.org/

^vi http://www.iasa-web.org/

^vii https://www.narodnifonoteka.cz/

^viii Waveform Audio File Format, also WAAVE or WAV, http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Docs/riffmci.pdf, p. 56–65.

^ix Broadcast Wave Format, also BWF, https://tech.ebu.ch/docs/tech/tech3285.pdf

^x Audio Interchange File Format, also AIFF, http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/Docs/AIFF-1.3.pdf

^xi E.G. certain animal and electronic instruments sounds that emit 22,05 kHz frequency or higher i.e. beyond human sound capability.

^xii DAT = Digital audio tape, digital sound stored on tape medium.

^xiii HAMILTON COLLEGE LIBRARY.Creating/Submitting Digital Audio. Digital Collections-Hamilton College Library [online]. Clinton, NY, 2013 [cit. 2016-12-02]. Available at: http://elib.hamilton.edu/digital-audio

^xiv However, can also entail compressed MP3 data, and have a .wav ending instead of .mp3.

^xv http://www.bac-lac.gc.ca/eng/services/government-information-resources/guidelines/Pages/guidelines-file-formats-transferring-information-resources-enduring-value.aspx#p

^xvi http://www.ed.ac.uk/files/atoms/files/recommended_file_formats-apr2015.pdf

^xvii http://lib.colostate.edu/repository/csu-digital-repository-preservation-format-support-policy

^xviii http://www.lib.utah.edu/collections/digital/best-practices.php

^xix https://conservancy.umn.edu/pages/policies/

^xx Research of 118 format policies of North American institutions between 2012-2013 states that the WAVE format was the preferred format 80 times and format AIFF 59 times.

^xxi Currently archived by the WAVE format

^xxii http://dublincore.org/

^xxiii http://www.loc.gov/standards/mods/

^xxiv http://pbcore.org/

^xxv Audio recordings description serves as a description that is stored on multiple mediums or TV series episode description etc. (ARSC, p.85)

^xxvi http://www.loc.gov/standards/premis/

^xxvii http://www.aes.org/publications/standards/search.cfm?docID=84, http://www.aes.org/standards/schemas/aes57-2011-08-27.xsd

^xxviii ARSC Guide to Audio Preservation, https://www.clir.org/pubs/reports/pub164/pub164.pdf

^xxix Regarding visual documents, the respective information could be entered into MIX scheme which serves for technical metadata entry.

^xxx This type of information can be important e.g. when used devices´ corrupted functionality emerges (scanner, codec). They can search out documents that were created by this respective device.

^xxxi DROID, Digital Record Object Identification, http://www.nationalarchives.gov.uk/information-management/manage-information/policy-process/digital-continuity/file-profiling-tool-droid/

^xxxii Siegfried, http://www.itforarchivists.com/siegfried

^xxxiii FIDO, Format Identification for Digital Objects, http://coptr.digipres.org/FIDO_(Format_Identification_for_Digital_Objects)

^xxxiv UK´s National Archive operates PRONOM format library, containing file format information including the so-called signature files which serve format identification via identification tools such as DROID, FIDO and Siegfried.

^xxxv DROID will be selected as the preferred identification tool unless further tests indicate otherwise – DROID is managed by reputable long-term storage organization (The National Archives).

^xxxvi JHOVE, JSTOR/Harvard Object Validation Environment, http://jhove.openpreservation.org/

^xxxvii MediaInfo, https://mediaarea.net/cs/MediaInfo

^xxxviii FITS, File Information Tool Set, http://projects.iq.harvard.edu/fits/home

^xxxix Apache Tika, https://tika.apache.org/

^xl Exiftool http://www.sno.phy.queensu.ca/~phil/exiftool/

^xli PET, PERICLES Extraction Tool, http://coptr.digipres.org/PERICLES_Extraction_Tool_(PET)

^xlii MediaInfo tool rounded up the recording´s duration during our test.