Delivery formats – to compress or not compress

Screenshot of software encoding a file to MP3 used at the Great Bear

After we have migrated your analogue or digital tape to a digital file, we offer a range of delivery formats.

For audio visual these include Apple Quicktime /MOV in any codec, 10 bit uncompressed (recommended), AVI in any codec; any MacOS, Windows or GNU/Linux filesystem (HFS+, NTFS or EXT3); DVCAM / miniDV and DVD.

For audio we offer Broadcast WAV (B-WAV) files on hard drive or optical media (CD) at 16 bit/44.1 KHz (commonly used for CDs) or 24 bit/96 KHz (which is the minimum recommended archival standard) and anything up to 24 bit / 192 Khz. We can also deliver access copies on CD or MP3 (that you could upload to the internet, or listen to on an ipod, for example).

Why are there so many digital file types and what distinguishes them from each other?

The main difference that is important to grasp is between an uncompressed digital file and a compressed one.

On the JISC Digital Media website, they describe uncompressed audio files as follows:

‘Uncompressed audio files are the most accurate digital representation of a soundwave, but can also be the   most resource-intensive method of recording and storing digital audio, both in terms of storage and management. Their accuracy makes them suitable for archiving and delivering audio at high resolution, and working with audio at a professional level, and they are the “master” audio format of choice.’

Why uncompressed?

As a Greatbear client you may wonder why you need a large, uncompressed digital file if you only want to listen to your old analogue and digital tapes again. The simple answer is: we live in an age where information is dynamic rather static. An uncompressed digital recording captured at a high bit and kHz rate is the most stable media format you can store your data on. Technology is always changing and evolving, and not all types of digital files that are common today are safe from obsolescence.

It is important to consider questions of accessibility not only for the present moment, but also for the future. There may come a time when your digitised audio or video file needs to be migrated again, so that it can be played back on whatever device has become ‘the latest thing’ in a market driven by perpetual innovation. It is essential that you have access to the best quality digital file possible, should you need to transport your data in ten, fifteen or twenty years from now.

Compression and compromise?

Uncompressed digital files are sound and vision captured in their purest, ‘most accurate’ form. Parts of the original recording are not lost when the file is converted or saved. When a digital file is saved to a compressed, lossy format, some of its information is lost. Lossy compression eliminates ‘unnecessary’ bits of information, tailoring the file so that it is smaller. You can’t get the original file back after it has been compressed so you can’t use this sort of compression for anything that needs to be reproduced exactly. However it is possible to compress files to a lossless format, which does enable you to recreate the original file exactly.

In our day to day lives however we encounter far more compressed digital information than uncompressed.

There would be no HD TV, no satellite TV channels and no ipods/ MP3 players without compressed digital files. The main point of compression is to make these services affordable. It would be incredibly expensive, and it would take up so much data space, if the digital files that were streamed to televisions were uncompressed.

While compression is great for portability, it can result in a compromise on quality. As Simon Reynolds writes in his book Retromania: Pop Culture’s Addiction to its Own Past about MP3 files:

‘Every so often I’ll get the proper CD version of an album I’ve fallen in love with as a download, and I’ll get a rude shock when confronted by the sense of dimension and spatiality in the music’s layers, the sculpted force of the drums, the sheer vividness of the sound. The difference between CD and MP3 is similar to that between “not from concentrate” orange juice and juice that’s been reconstituted from concentrate. (In this analogy vinyl would be ‘freshly squeezed, perhaps). Converting music to MP3 is a bit like the concentration process, and its done for much the same reason: it’s much cheaper to transport concentrate because without the water it takes up a lot loss volume and it weighs a lot less. But we can all taste the difference.’

As a society we are slowly coming to terms with the double challenge of hyper consumption and conservation thrown up by the mainstreaming of digital technology. Part of that challenge is to understand what happens to the digital data we use when we click ‘save as,’ or knowing what decisions need to be made about data we want to keep because it is important to us as individuals, or to wider society.

At Greatbear we can deliver digital files in compressed and uncompressed formats, and are happy to offer a free consultation should you need it to decide what to do with your tape based digital and analogue media.

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