Aliasing – a phenomenon resulting from the failure of a digital system to accurately reproduce at the output the signal that was put into it. It’s important for digital audio systems to faithfully reproduce the original sound that was put in. In this case if the sampling frequency is not adequate a completely different (alias) sound results. Also see Sampling Frequency, Analog to Digital Conversion.
Amplifier – an electronic audio device that increases the volume of the sound by adding power to that sound (or signal). Also see Signal.
Analog – an electrical signal that is continuous and unbroken and an electrical analogy of some real world phenomenon. In the case of sound the electrical analog is an audio signal and, in simple terms, the bigger the audio signal the louder the sound or the smaller the audio signal the quieter the sound. In practice audio signals are more complex and contain more information than this.See also Analog to Digital conversion, digital, Signal.
Analog to Digital Conversion – a method of ‘translating’ a continuous signal (i.e. analog) into binary digits for use in the digital domain (i.e. in computer) or, put simply, converting the analog signal into a language that computers can understand. Also see Aliasing, Digital, Digital to Analog conversion, Binary Digit, Sampling Frequency and Bit Depth.
Announcement Control – part of the BMasia player that allows the viewing of tracks and their programming, it forms a secondary playlist from which festival and theme night music is played (i.e. Xmas, Chinese New Year etc.). Also See Music Control and BMS.
Audio Over CAT5 – is a method of using inexpensive CAT5 cable in conjunction with Baluns boxes to balance an analog audio signal such as those from the output of a PCs sound-card. Put simply balancing the audio in this way means being able to send analog audio signals over very long distances (2500 Feet or 760 Meters) while maintaining the audio quality. Also See Balanced and Unbalanced Audio, Baluns Box.
Balanced and Unbalanced Audio – balanced audio is a way of connecting up audio equipment in such a manner that long cable runs can be used without any severe reduction in audio quality. An example of a balanced audio line would be XLR. Unbalanced audio lines such as RCA can be found on domestic audio equipment and are cheap, but cable lengths must short or audio quality will degrade very quickly.
Baluns Box – a small passive (non-powered) device used to balance an unbalanced analog audio signal in order to deliver these signals over CAT5 (network) cables. The advantage is that the cable distances can be very long; up to 2500 Feet without noticeable loss of quality. Also see Audio over CAT5, Balanced and Unbalanced Audio.
Bit Depth – the number of bits (binary Digits) used per sample. Bit Depth dictates the resolution or accuracy with which the digital conversion translates the original signal or sound. For audio CDs bit depth is 16 bits. Professional Digital Audio recording uses 24 Bits. Also see Analog to Digital Conversion, Binary Digit and Sampling.
Binary Digit – AKA a bit. In a computer system a bit is represented by the data signal being High (i.e. a 1) or a Low (i.e. a 0). We humans use the notations 0 or a 1 for convenience there are no 0s or 1s in computers only signal levels High or Low. Also see Bit Depth, Analog to Digital Conversion and Digital to Analog Conversion.
Buffer – specialized memory used to smooth out variations in arrival of data packets in media streaming (i.e. Video or Audio). Media data has to be continuous; any break caused by a late arrival of a data packet will cause an interruption (black hole or silence or stutter) in the media.
Centralized System – this refers to the configuration of your hotel’s audio system. A centralized system means simply that all music sources are kept in one location in the hotel (i.e. CCTV room IT Server etc…) and from here all these music sources are routed to each outlet location. The multiple sources are usually on one PC containing many music players. The PC’s music sources are connected to a routing box (DSP) from where audio is routed to the correct area. See Single Systems and COBRANET.
CODEC – a contraction of Coder and Decoder or Compressor and Decompressor. It is a hardware or software device that takes an analog input and converts it to Digital or a Digital input into analog or another digital format. It can also convert it back. It can take raw digital data and compresses it or decompress it.
COBRANET – audio over Ethernet. A collective solution comprising of Software, Hardware and Protocols designed to run non compressed multi-channel audio over a digital network. Advantages are control and flexibility. It does not suffer from the usual degradation problems found in analog audio delivery solutions. If your hotel music system is centralized, chances are the equipment is using COBRANET. See Centralized Systems.
Digital – a way of referring to systems that work in the digital domain or signals that convey information as binary data (i.e. on computers DVDs). Also see Binary Digit.
Digital to Analog Conversion – once the computer has finished with the digital audio or video signal you want to see or hear the result. In order to do this the binary digits have to be converted or translated back into an analog signal and then in this form can be run to speakers, TV screens, monitors, etc. This process is known as digital to analog conversion. Also see Digital and Analog to Digital Conversion.
Digital Data Compression – don’t get this confused with dynamic range compression. In this case it means simply reducing the number of bits in a digital data file (audio or video) to make it smaller. Also see MPEG, MP4 MP3.
DSP (Digital Signal Processor) – is a device used for treating digital signals. This could mean filtering, the addition audio effects, signal routing and sometimes all of them. In the context of an Hotel Audio system a DSP refers to the central audio router in a centralized audio system. Its main function is to route audio to its correct location. However it is also able to carry out engineering processing functions such as compression, limiting, preamplification, filtering and gain control. See Centralized System, COBRANET, Dynamic Range Compression, and Gain.
Dynamic Range Compression – simply put this is a method that ensures that the volume levels are held steady i.e. that the audio does not become too quiet or too loud. Devices that carry out this task can be implemented in hardware or software. The BMasia players contain a software compressor which is set up by BMAsia on installation. Also see Dynamic Range.
Dynamic Range – the difference between the quietest sound and the loudest. If the difference is great, it is said to have a Wide Dynamic Range. A common example of this would be a Movie or DVD where someone talking maybe barely perceptible and then a door slamming in the next instant is extremely loud. This can be undesirable since you might have to turn the volume up to hear the speech and then back down for noisy action sequences. Compression reduces the Dynamic range of the audio signal. Also see Dynamic Range Compression and BMAsia Guide to Dynamic Range Compression.
Equalizer – an audio device that can be hardware or software based that is designed to selectively change the bass, treble (high/low) and other frequency components of the audio signal to improve the quality and clarity of the sound. The BMasia player contains a basic equalizer which simply controls bass and treble levels (basic equalization). Care needs to used when setting these devices up as they can contribute to issues such as variable level audio.
FAT (File Allocation Table) – a part of the hard disk that contains the locations of ALL files stored on the Hard Disk. It’s an index or look up table. This is setup when the disk is formatted. All clusters (i.e. contiguous chunks or storage) are registered in the table. They are either free for use or used by a file and the table keeps a record of which clusters are used for every file you store on the disk. There are many variants, FAT16, FAT32, exFAT, etc some of which are completely obsolete. FAT32 and exFAT are still in use for SD cards and USB flash drives,etc. exFAT is a Microsoft version of FAT32 and simply extends some of the FAT32 functionality, i.e. the range of cluster sizes that can be used. Also see Hard Disk Drives and NTFS.
Firewire – is Apple’s name for the IEEE 1394 High Speed Serial Bus that allows extremely fast bit rates for media applications such as audio. Like USB it is a serial interface, i.e. data is transferred one bit at a time. Also see USB.
FLAC (Free Lossless Audio Codec) – similar to MP3 except that it uses lossless compression and the audio quality is therefore higher. File size is much larger than MP3.
Frequency – the regularity with which a signal repeats itself. In audio the higher the frequency the higher the pitch, the lower the frequency the lower the pitch; bass refers to low frequencies, treble refers to high frequencies. So a violin has higher frequency sound than say a double bass or bass guitar. Frequency is measured in cycles or signal repeats per seconds or Hz (Hertz). Also See Signal.
Gain – the measure of a device such as an amplifier to increase the power of a signal between the input and the output. Gain is measured in DB or decibels. Also See Amplifier and Signal.
Hard Disk Drive – part of a computer that stores Data (files) and the computers operating system (i.e. Windows or Linux). It consists of a number of disks or platters in a container each of which has a read/write head on an actuator arm. Data is read from the disks as required by the system and written to when something needs to be stored. Also see FAT and NTFS.
IP Address – all computers on a network need one of these. IP means Internet Protocol. The address has to be unique for that PC on that network. It is a bit like the number of your house in your street and is used to identify a PC on a network for communication and data transfer purposes. Also see MAC Address, Subnet Mask.
LAN (Local Area Network) – is a computer network that your computer is directly connected to via its LAN port or WiFi connection. It is not the internet but may allow access to it. Also See VLAN.
Linux – a computer operating system developed in the early 1990s that was built on the earlier UNIX operating system developed in the 1960/70s. Not as user friendly as Windows but is considered as more reliable, secure and flexible with the added advantage that it is free. Google’s Android Operating System is a much modified version of Linux. Also See Operating System
MAC Address – media Access Control. Sometimes referred to as a hardware address. This is the absolute address hardwired into every LAN device. It cannot be changed, is unique and is absolute unlike an IP address which can easily be altered in Windows. An example would be 00-30-1B-BB-25-A8. Also see IP Address.
MP3 – refers to MPEG 2 (or MPEG 1) audio layer III (hence the 3) compression for data rate reduction. It’s a way of making audio files or tracks smaller according to a specific set of computational tools. This means they are quicker to copy and take up less storage space. iPods and similar devices play MP3 audio.
MP4 – the ‘successor’ to MP3 and refers to MPEG 4 compression standard which part of the Advanced Audio Codec standard. Strictly speaking it should be referred to as M4a if its an audio only file. MP4 or M4a produces smaller files sizes and improved audio quality. iPods and similar devices play M4A and MP4 video files.
MPEG (Motion Pictures Experts Group) – a crafty bunch of engineers who came up with MPEG I, MPEG2, MPEG4 standards and all the other data compression stuff. See MP3, MP4 and Data Compression.
Music Control – part of the player that allows the viewing of tracks and their programming information and constitutes the main playlist of the player. Also See Announcement Control.
NTFS (New Technology File System) – the successor to FAT32, and is used in most computers to organise and manage files on a HDD. Also see FAT and HDD.
Operating System – a specialised software suite that runs on a computer and manages it for you and makes it easy for you to operate it. It deals with complex technical tasks so you don’t have to. Examples are WinXP, Win7, Win8, Linux, iOS, Android. Also see HDD.
PCI (Peripheral Component Interconnect) – a PC bus standard, your PCs motherboard may contain (usually) white slots into which an expansion card will fit. Examples of such cards are Audio Interfaces, VGA cards and LAN cards. This is an old standard and is being gradually phased out on newer motherboards. PCI has been superseded by the much newer PCIe. See Audio Interfaces, PCIe.
PCIe or PCI Express – the successor to the much older PCI standard. It features many improvements over PCI, among them faster maximum data throughput, lower pin count and therefore smaller slot sizes, improved error detection and handling.
Programming – this refers to the processes of adding scheduling information to the tracks playing in the BMS, i.e. what time of the day, what day of the week etc. (also see RAF files).
Protocol – a set of rules that allow two devices to communicate and transfer data. Also see UDP, TCP, IP Address and Cobranet.
Quantisation – the final part of the Analog to Digital Conversion process. Each sample height is measure against a kind of ruler marked in binary numbers. This binary number is then used to represent the value of that sample in the digital domain. Also see Analog to Digital Conversion, Binary Digit and Sampling Frequency.
RAM (Random Access Memory) – is a solid-state data storage device, i.e. a chip that can be directly accessed in any random order. Other types of storage such as Hard Disk Drives, Tape Drives, CDs, DVDs etc. store data in a predetermined order. RAM is usually volatile, that is to say it will lose any data stored in it if the power to the device is turned off.
RAF File – in BMasia system each MP3 track has its own RAF file which contains programming or scheduling information such as the time of the day and or day of the week that the track is supposed to play. Also see Programming.
RCA connector – also known as a phono-connector and is an audio connector that is commonly found on domestic CDs, DVDs and music centers. It can also be used to connect composite and component video. Audio connectors are usually white or red (audio left and audio right) yellow is usually analog composite video. Also see Balanced and Unbalanced audio.
Sampling Frequency – or Sampling Rate. Not to be confused with Bit Rate although it is related. Sampling is part of the process of translating a signal into digits. Sampling takes a periodic ‘snapshot’ of the analog signal. The number of snapshots or samples per second is the sampling frequency. The sampling rate for CDs is 44.1kHz. Also see Analog to Digital Conversion, Binary Digit.
Signal – an engineering term that refers to information in an electrical system that conveys important detail about real world phenomenon, ie. light = video signal how bright, how dark, sound = audio signal how loud, how quiet etc. Signals can also convey information about heat and pressure and so on. In the case of Analog signals the louder the sound or brighter the image the larger the voltage of the signal. Signals can be analog or digital. Also see Analog and Digital.
Single System – this refers to a type of configuration in a hotel audio system. A single system means simply that each outlet has its own independent and separate amplifier and speakers. See Centralized System and COBRANET .
Sound-card – sometimes referred to as an audio interface. In its most simple form it gets the audio stored digitally on the computer out into the real world where you can hear it (playback) and also back in again (recording). These devices usually have their own memory and processors on them to relieve the computers CPU from having to deal with some of the more computationally intensive tasks such as signal processing i.e. compression, equalisation, and conversion from digital to analog. In some cases it will come with its own internal mixing and routing functions to allow multiple channels of audio into and out of the computer. This kind of sound-card is referred to as a Multi-Channel Sound-card.
Streaming – a way of delivering multimedia (Video and Audio) to PCs over a network. The main advantage is that Media can be played almost immediately without waiting for the whole file to download. Also the file does not need to be stored on the receiving PC thus keeping the media safe at the sending end.
Subnet Mask – simply put a subnet mask is used to separate the network part of an IP address from the host (PC) part. This is so that the system knows which sub-network to go to find the host and then which host on that subnet to go to. A typical subnet mask is 255.255.255.0 for class C networks. The first three numbers are for the network, the last digit is for the host address. The subnet mask is used in a binary arithmetical calculation with the IP address in order to resolve the two parts. Also see IP Address.
TRS Connector – TRS stands for Tip Ring Sleeve and refers to parts of the connector; tip = stereo left, ring (middle) = stereo right and sleeve = ground. TRS can refer to the mini jack connectors found on the earphones of iPods or the 1/4 inch and larger version that can be seen on some amplifiers and audio mixers.
UPS (Uninterrupted Power Supply) – a device that is used to supply essential equipment with power during interruptions to the mains power supply.
URL (Uniform Resource Locator) – a web address or a character string that represents the location on the internet of the webpage you wish to download to your browser.
USB (Universal Serial Bus) – is an easy way of connecting external devices such as flash storage drives and multimedia devices without complex operational procedures to get them going i.e. it is plug and play (more or less!) Like Firewire it is a serial interface where data is transferred one bit at a time. Also see Firewire.
Variable Level Audio – a fault in an audio system where the volume level of the music either changes while the track is playing or changes between music tracks. These faults can have many causes including faulty cables or incorrect settings on equalizers and amplifiers. If you are having these issues contact BMS support for assistance and advice.
VBR (Variable Bit Rate) – in compressed formats such as MP3, setting the compression to VBR means the CODEC will assign more bits to the complex part of the music and less bits to the simpler parts. The bit rate is therefore not constant though the whole file.
VLAN – simply put is a Virtual Local Area Network. A VLAN creates a logically partitioned, isolated network within the same network infrastructure and the rest of the network. This is NOT to be confused with a Subnet. Data and resources on the main network are not available to machines on the VLAN and vice versa. VLANs offer security for the PCs connected to it and also for the rest of the network if the VLAN is exposed to external traffic that may pose a potential security risk. Also see LAN.
WAV – waveform Audio File Format is a digital audio file format developed by Microsoft and IBM and is normally uncompressed.
XLR connector – an audio connector that is mainly found in professional audio (i.e. In TV, Radio and Recording Studios), the XLR is the industry standard for balanced audio. Also see Balanced and Unbalanced audio and BMAsia guide to Balanced and unbalanced audio.
32/64 bit computer systems – with the advent of Windows 7 and improvements in computer design technology, 64 bit systems are becoming increasingly common. Systems over the past 10 years or so have been mainly 32 bit systems. So what does it all mean? It is an important aspect of the internal architecture of a PC. Computers move data around on things called buses; imagine it like a highway with 32 lanes. The bus has 32 wires (or lanes) running in parallel each wire transfers one bit in any given clock cycle. Because all the wires are parallel 32 bits can be transferred in any one clock period one bit on each wire. So if the number of wires on the bus increases the greater the number of bits can be transferred in any given period hence the 64 bit system will be faster and more powerful than its 32 bit counterpart. But it doesn’t stop there; a 64 bit system is able to access more RAM, usually around 4GB, than the 32 bit versions whose upper limit is around 2GB.
UDP – a protocol for transferring data over the internet. It’s a simple low overhead method of getting data packets across the internet and, because of this, it does not guarantee arrival at the other end. It can be regarded as a ‘send and pray’ method. Because there are no methods for checking and guaranteeing delivery its actually faster which makes it more suited for media delivery ie Audio and Video.
TCP (Transmission Control Protocol) – another method of transferring data packets across the internet. Unlike UDP it has a complex mechanism for checking and guaranteeing the delivery of the data. The mechanism would be analogous to giving a letter to the postal service and the postman then calls you to let you know if the letter has arrived safely or not. If not then the letter is sent again.
