ComputerFixed.co.uk Page: 1 Email: info@computerfixed.co.uk UNDERSTANDING MUSIC & VIDEO FORMATS Are you confused with all the different music and video formats available? Do you know the difference between Org and MP3 or AVI and MPG? Here at ComputerFixed we aim to keep our clients up to date with computer terminology. As there are a wide range of video and music formats, we have produced this fact sheet, to help you understand and make a educated decision on what format is best for you. Introduction to music formats Since the introduction of the Compact Disc in the 1980's, digitally encoded audio has become the most popular method of playing audio in history. Today digital compression audio is quickly changing the way the world buys, distributes, and listens to music. A CD holds music in what is known as the Pulse Code Modulation (PCM) format, which is a common method for digitizing analogue signals. PCM signals are uncompressed, which means that after the conversion, the resulting digital stream will take up a great deal of space. In fact, CDs stream data off the disc at a rate of 1.41 million bits per second. This means that 30 minutes of audio will take up approximately 318 Megabytes of space, which is simply too large to efficiently store in a computer, load into a portable, or send over the internet. Compression is the process of reducing the size of the digital signal, while still keeping the quality as close as possible to the original source. Throughout the 80's and much of the 90's, there was no great way to accomplish this task at home. Then it happened. The arrival of the MP3 format shook the world. Since its release, the ability to compress music into tiny sizes has created many benefits, and many problems at the same time. Also, the market has since been flooded with many different audio compression methods that have made the process much more complicated than it has ever been before. This article will focus on the most popular digital compression formats.
ComputerFixed.co.uk Page: 2 Email: info@computerfixed.co.uk The different music formats: Listed below are the most popular Windows computer music formats. MP3 (.mp3) The MPEG Layer-3 format is the most popular format for downloading and storing music. By eliminating portions of the audio file that are essentially inaudible, mp3 files are compressed to roughly one-tenth the size of an equivalent music file while maintaining good audio quality. We recommend the mp3 format for music storage. It is not that good for voice storage. WMA - Windows Media Audio (.wma) Short for Windows Media Audio, WMA is a Microsoft file format for encoding digital audio files similar to MP3 though can compress files at a higher rate than MP3. WMA files, which use the ".wma" file extension, can be of any size compressed to match many different connection speeds, or bandwidths. Designed with Digital Rights Management (DRM) abilities for copy protection. WAV (.wav) The standard audio file format used mainly in Windows PCs. Commonly used for storing uncompressed (PCM), CD-quality sound files, which means that they can be large in size - around 10MB per minute of music. WAV sound files end with a.wav extension and can be played by nearly all Windows applications that support sound. Real Audio (.ra.ram.rm) Real Audio is a proprietary format, and is used for streaming audio that enables you to play digital audio files in real-time. To use this type of file you must have RealPlayer (for Windows or Mac), which you can download for free. Real Audio was developed by RealNetworks. MIDI - Musical Instrument Digital Interface (.mid) Short for musical instrument digital interface, MIDI is a standard adopted by the electronic music industry for controlling devices, such as synthesizers and sound cards, that emit music. At minimum, a MIDI representation of a sound includes values for the note's pitch, length, and volume. It can also include additional characteristics, such as attack and delay time. Ogg (.ogg) OGG is the nickname for Ogg Vorbis, which is an open source, royalty free audio compression format. OGG has gained ground since its launch, mostly because it produces exceptional quality results, and is completely free for manufacturers to implement in their hardware and software players. OGG contains many of the same features that the major formats like MP3, WMA, and AAC contain, as well as a few unique features to itself. Though it's the most popular of the free formats, it has a long way to go before it becomes a widely compatible format. Most of the software players have a plug-in to support OGG, but few portables devices play OGG files natively.
ComputerFixed.co.uk Page: 3 Email: info@computerfixed.co.uk What audio format will I choose? The formats explained here are only the most popular. There are plenty of other audio formats to pick from if you are looking for the best sounding one to you. Choosing a format ultimately depends on personal preferences. An important consideration is to find the best format that is compatible with the hardware you own. On a computer, you have the ability to playback all formats, but your portable music device will probably only be compatible with a few of them. MP3 is currently the most compatible of formats, but the sound quality of newer compression schemes might make them a better choice for you. The different video formats Listed below are the most popular video formats on a Windows computer..swf The Shockwave format was developed by Macromedia. The Shockwave format requires an extra component to play. This component comes preinstalled with the latest versions of Netscape and Internet Explorer. Videos stored in the Shockwave format have the extension.swf. AVI The AVI (Audio Video Interleave) format was developed by Microsoft. The AVI format is supported by all computers running Windows, and by all the most popular web browsers. It is a very common format on the Internet, but not always possible to play on non-windows computers. Videos stored in the AVI format have the extension.avi..mov The QuickTime format is developed by Apple. QuickTime is a common format on the Internet, but QuickTime movies cannot be played on a Windows computer without an extra (free) component installed. Videos stored in the QuickTime format have the extension.mov..rm or RAM The RealVideo format was developed for the Internet by Real Media. The format allows streaming of video (on-line video, Internet TV) with low bandwidths. Because of the low bandwidth priority, quality is often reduced. Videos stored in the RealVideo format have the extension.rm or.ram.
ComputerFixed.co.uk Page: 4 Email: info@computerfixed.co.uk.mpeg The MPEG (Moving Pictures Expert Group) format is the most popular format on the Internet. It is cross-platform, and supported by all the most popular web browsers. Videos stored in the MPEG format have the extension.mpg or.mpeg..wmv The Windows Media format is developed by Microsoft. Windows Media is a common format on the Internet, but Windows Media movies cannot be played on non-windows computer without an extra (free) component installed. Some later Windows Media movies cannot play at all on non-windows computers because no player is available. Videos stored in the Windows Media format have the extension.wmv. Important Terminology BIT RATE A song s bit rate is a measurement of the amount of data being transmitted or processed. As a song is played back or recorded, there is a transfer of data, measured in kbps (kilobits per second; a kilobit is one thousand bits). As the bit rate increases so does the quality of the song. For example, although 128kbps is considered to be the standard for MP3s in terms of quality versus file size, an MP3 file encoded at 192kbps may sound noticeably better. CODEC An acronym for compression/decompression. Codecs are components - either hardware or software - which compress the size of a media file during saving and decompress the file during playback. DRM Also known as digital rights management, these copy-protection schemes are used by music distributors such as Apple s itunes Music Store to restrict their songs from being played on other computers or digital-music devices. FAIRPLAY Apple s form of DRM, which prevents unauthorized computers and non-ipod digital music players from playing songs bought from the itunes Music Store.
ComputerFixed.co.uk Page: 5 Email: info@computerfixed.co.uk ID3 TAG In MP3 files, the ID3 tag allows song information such as the title, artist, album, track number, and so on to be stored in the file itself. LOSSLESS COMPRESSION This type of codec allows file compression while keeping all of the file s original quality. Some examples are the Apple Lossless Encoder, FLAC, and the common file-compression format known as ZIP. LOSSY COMPRESSION This type of codec discards some data in order to make songs small - usually, however, the drop in quality due to the discarded data is not noticeable except to the most discerning ear. MP3, JPEG, and Ogg Vorbis are all lossy-compression formats. MONO Short for monophonic, a mono audio system pumps all the sound through only one channel - even if you have multiple speakers connected to your audio source, you ll hear the same sound from each of your speakers. PLAYSFORSURE Microsoft's form of DRM. ipods and itunes cannot play music encoded with Microsoft's DRM. SAMPLE RATE A digital audio file s sample rate indicates how many times the signal was measured when it was converted from an analog signal to a digital one. Sample rates are measured in Hz, and as the sampling rate increases so does the audio quality. Also note that to maintain sound quality, the sampling rate must be twice the original audio s highest frequency. The standard CD and MP3 sample rate is 44.100kHz. STEREO Short for stereophonic, a stereo audio system distributes sound through two separate channels, left and right. The amount of the same sound coming from the two speakers determines where that sound appears to be coming from in the stereo field; a sound coming from only the left speaker, for example, sounds as if it s coming from - you guessed it - only the left, while an equal amount of a sound coming from both speakers appears to be emanating from the middle of the stereo field. SURROUND SOUND Sound distribution that involves multiple channels (ranging from three to ten) to create a sense of realism. For example, some DVD movies have audio tracks that can use five different channels.