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| College Work: Music Production: Audio In Multimedia | |||
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Audio In Multimedia Kieran McAtamney-Sanders Brief: Discuss the importance of quality audio within future multimedia authoring and web developments. Discuss the skills that you think are transferable from the traditional music producer to a multimedia author. Also explore future possibilities and expectations of audio over the web. Deliverables • An essay of 2,000 words exploring the issues surrounding Audio in Multimedia Chapter 1: Introduction Audio In Multimedia Today: In this essay, I will be exploring the issues surrounding the various delivery formats available for audio in multimedia and the Web, and their impact on sound design ethos and practice, as well as the implications of possible future developments. In its current state, sound design for multimedia is often basic, to say the least- audio is often the last consideration, when it is considered at all. In the vast majority of cases, audio is not are integral part design process. The There are a variety of reasons for this, both technological and social. The technological factors largely arise from the limitations on the effectiveness of today’s delivery formats; these technologically applied restrictions will disappear in time as the technology advances. However, at least as important are the social restrictions placed on audio in multimedia. The designers of multimedia products are usually more focused on the visual area of the field, professional sound designers / producers are rarely involved. These issues will also be resolved in time (indeed the very course for which I am writing this essay is evidence that this change is already in progress). As technological limitations become less important, multimedia design will hopefully become more integrated process with audio no longer regarded as something to be ‘bolted-on’ at the last minute, but an integral part of the whole product. The state of audio on the Web is similar to that in the rest of multimedia, though somewhat exaggerated due to the far harsher technical restrictions imposed by connection speeds. Technical Limitations: In Chapter 2, I will examine the various delivery formats for audio in multimedia, and look at the advantages and disadvantages of each , and the implications to designer of their use. First however, I will examine the common limitations on audio delivery, since almost all of the formats I will be examining have been specifically designed to overcome these limitations. There are two basic characteristics of audio which can be limited when preparing it for use in multimedia; its data rate, and its total file size. These two are obviously related, it is important to keep both in mind when preparing audio. Data Rate: The data rate is usually restricted either in an attempt to keep the overall file size down or because of special considerations such as streaming. If audio is to be streamed, especially over the Internet, it is vital that the data rate be low enough to allow the user to play it with as little interruption as possible. This usually means keeping the data rate below the effective maximum speed of a 56 K modem, somewhere in the region of 4-5kb/sec. This can be achieved by simply lowering the sample rate and resolution, though the damage to the quality of the audio usually means that some kind of compression algorithm is preferred. File Size: File size can be restricted for two reasons; limitations on available storage space (for example on a CD ROM), or in an attempt to keep download times manageable. Again, for the Internet it is necessary to consider that many users still only have a 56 K modem. Thus, a one megabyte file (about six seconds of CD-quality audio) will take between one and two minutes to download! File size can be reduced by reducing the data rate, or by actually shortening the duration of the audio clip. As with data rate, thouth some results can be achieved by lowering the sample rate and resolution, again, various forms of compression are usually preferred. Compression: The most popular methods for audio delivery involve file compression to reduce the overall file size. Today’s popular compression formats, including AC3 and MP3, all make use of Lossy Compression, which means that using them permanently reduces the quality of the audio. Today’s compression formats make use of psycho-acoustic theory such as audio masking, allowing file size to be reduced by stripping out frequencies which will not be noticed by the casual user, and by removing stereo data for bass frequencies which have too long a wavelength to be recognisably detectable in smaller rooms, though the difference is still noticable to the trained ear. The sophistication of compression algorithms is constantly increasing, so that the quality becomes closer and closer to that of uncompressed audio, though any compression at all is still ultimately to the detriment of sound quality. Chapter 2: Delivery Formats MP3: By far the most popular format for audio delivery on the Web, and other multimedia applications, is the MP3 format. Originally intended as a complete audio/video codec, MPEG-3 has since become widely adopted as a format for the distribution of audio. Using lossy compression, MP3 intelligently strips out data which would be largely inaudible to the casual listener (such as stereo information for bass frequencies). When creating an MP3 file, the user selects the final data rate, ranging from 192kb/s, which is usually sufficient for the delivery of music at something sounding reasonably close to CD quality, to as low as 32kb/s for low quality sound effects/speech. The quality of MP3 compression is to a large extent dependant on the encoding software used- an MP3 created at 192kb/s two or three years ago will sound significantly worse than one created at the same data rate using the latest compression algorithms. MP3 Has become the dominant format for music distribution on the Web, largely due to the success of the Napster service, and despite attempts by various companies including Microsoft to introduce new formats, remains by far the most popular. Realaudio: Despite the popularity of MP3, Realaudio has maintained something of a niche in the Web audio market. Despite its low quality, Realaudio remains the most popular option for streaming audio on the Web, used for Internet radio and live Webcasts. The quality of real audio files is relatively low, necessarily so, to allow effective streaming even over a 56k dial-up connection. However, as uptake of broadband services such as ADSL increases, it is likely that MP3 or its descendant, MP4, will come to dominate this section of the market as well. Chapter 3: Copyright Concerns The development of effective audio compression formats, particularly MP3, has caused a great deal of concern for record companies as to how to best protect their Copyright. Although the famous Napster file sharing system has now been brought to heel by legal action, a number of peer-to-peer file sharing applications are still out there on the Web (the more popular of these include Bearshare and Audiogalaxy.). This raises continued concern over music piracy. There exists no easy solution for record companies. For every new technology introduced to curtail unauthorised duplication, a number of cracks and work-arounds seem to emerge almost immediately. In the short term there is little that can be done to prevent this, though in the longer term I foresee record-companies introducing some form of pay-per-listen system, similar to that currently used for pay-per-view movies and sporting events via digital TV. At present however, record companies seem to be placing their faith in the relative complexity of file sharing technology keeping it beyond the reach of the majority of their customers. Chapter 4: Conclusions With ever increasing Internet connection speeds, and higher capacity portable media (DVD and the upcoming three-dimensional optical storage systems) it seems likely to me that in the not-too-distant future there will come a time when audio compression becomes unnecessary, as connections and media capacities will be able to cope with uncompressed CD-quality audio. In the meantime, increasing connection speed and media capacity will make integration of high-quality audio into multimedia applications increasingly feasible. As the technical limitations on using audio diminish, it is likely that audio will become a more integral part of the multimedia world, perhaps reaching the point where employing a sound engineer will become a necessity for Web design and multimedia firms. It is also worth noting that the use of multimedia content is becoming more and more widespread in the music industry, with the introduction of enhanced CDs. There will perhaps come a day when multimedia content on an artist’s CD becomes as much a prerequisite of a successful release as the music video has become in recent years. |
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