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AMR-WB
Adaptive Multi-Rate Wideband (AMR-WB) is a patented wideband speech audio coding standard developed based on Adaptive Multi-Rate encoding, using a similar methodology to algebraic code-excited linear prediction (ACELP). AMR-WB provides improved speech quality due to a wider speech bandwidth of 50–7000 Hz compared to narrowband speech coders which in general are optimized for POTS wireline quality of 300–3400 Hz. AMR-WB was developed by Nokia and VoiceAge and it was first specified by 3GPP. AMR-WB is codified as G.722.2, an ITU-T standard speech codec, formally known as ''Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB)''. G.722.2 AMR-WB is the same codec as the 3GPP AMR-WB. The corresponding 3GPP specifications are TS 26.190 for the speech codec and TS 26.194 for the Voice Activity Detector. The AMR-WB format has the following parameters: * Frequency bands processed: 50–6400 Hz (all modes) plus 6400–7000 Hz (23 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adaptive Multi-Rate
The Adaptive Multi-Rate (AMR, AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbit/s with toll quality speech starting at 7.4 kbit/s. AMR was adopted as the standard speech codec by 3GPP in October 1999 and is now widely used in GSM and UMTS. It uses link adaptation to select from one of eight different bit rates based on link conditions. AMR is also a file format for storing spoken audio using the AMR codec. Many modern mobile telephone handsets can store short audio recordings in the AMR format, and both Free software, free and proprietary programs exist (see #Software support, Software support) to convert between this and other formats, although AMR is a speech format and is unlikely to give ideal results for other audio. The common filename extension is .amr. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adaptive Multi-Rate Audio Codec
The Adaptive Multi-Rate (AMR, AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbit/s with toll quality speech starting at 7.4 kbit/s. AMR was adopted as the standard speech codec by 3GPP in October 1999 and is now widely used in GSM and UMTS. It uses link adaptation to select from one of eight different bit rates based on link conditions. AMR is also a file format for storing spoken audio using the AMR codec. Many modern mobile telephone handsets can store short audio recordings in the AMR format, and both free and proprietary programs exist (see Software support) to convert between this and other formats, although AMR is a speech format and is unlikely to give ideal results for other audio. The common filename extension is .amr. There also exists another stor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wideband Audio
Wideband audio, also known as wideband voice or HD voice, is high definition voice quality for telephony audio, contrasted with standard digital telephony "toll quality". It extends the frequency range of audio signals transmitted over telephone lines, resulting in higher quality speech. The range of the human voice extends from 100 Hz to 17 kHz but traditional, voiceband or narrowband telephone calls limit audio frequencies to the range of 300 Hz to 3.4 kHz. Wideband audio relaxes the bandwidth limitation and transmits in the audio frequency range of 50 Hz to 7 kHz. In addition, some wideband codecs may use a higher audio bit depth of 16 bits to encode samples, also resulting in much better voice quality. Wideband codecs have a typical sample rate of 16 kHz. For superwideband codecs the typical value is 32 kHz. History In 1987, the International Telecommunication Union (ITU) standardized a version of wideband audio known as G.722. Radi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VMR-WB
Variable-Rate Multimode Wideband (VMR-WB) is a source-controlled variable-rate multimode codec designed for robust encoding/decoding of wideband/narrowband speech. The operation of VMR-WB is controlled by speech signal characteristics (i.e., source-controlled) and by traffic condition of the network (i.e., network-controlled mode switching). Depending on the traffic conditions and the desired quality of service ( QoS), one of the 4 operational modes is used. All operating modes of the existing VMR-WB standard are fully compliant with cdma2000 rate-set II. VMR-WB modes 0, 1, and 2 are cdma2000 native modes with mode 0 providing the highest quality and mode 2 the lowest ADR. VMR-WB mode 3 is the AMR-WB interoperable mode operating at an ADR slightly higher than mode 0 and providing a quality equal or better than that of AMR-WB at 12.65 kbit/s when in an interoperable interconnection with AMR-WB at 12.65 kbit/s. Now also a cdma2000 rate-set I compliant mode is implemented to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO Base Media File Format
The ISO base media file format (ISOBMFF) is a container file format that defines a general structure for files that contain time-based multimedia data such as video and audio. It is standardized in ISO/IEC 14496-12, a.k.a. MPEG-4 Part 12, and was formerly also published as ISO/IEC 15444-12, a.k.a. JPEG 2000 Part 12. It is designed as a flexible, extensible format that facilitates interchange, management, editing and presentation of the media. The presentation may be local, or via a network or other stream delivery mechanism. The file format is designed to be independent of any particular network protocol while enabling support for them in general. The format has become very widely used for media file storage and as the basis for various other media file formats (e.g. the MP4 and 3GP container formats), and its widespread use was recognized by a Technology & Engineering Emmy Award presented on 4 November 2021 by the National Academy of Television Arts and Sciences. Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speech Coding
Speech coding is an application of data compression of digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic data compression algorithms to represent the resulting modeled parameters in a compact bitstream. Some applications of speech coding are mobile telephony and voice over IP (VoIP). The most widely used speech coding technique in mobile telephony is linear predictive coding (LPC), while the most widely used in VoIP applications are the LPC and modified discrete cosine transform (MDCT) techniques. The techniques employed in speech coding are similar to those used in audio data compression and audio coding where knowledge in psychoacoustics is used to transmit only data that is relevant to the human auditory system. For example, in voiceband speech coding, only information in the frequency band 400 to 3500 Hz is transmitted but the reconst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algebraic Code-excited Linear Prediction
Algebraic code-excited linear prediction (ACELP) is a speech coding algorithm in which a limited set of pulses is distributed as excitation to a linear prediction filter. It is a linear predictive coding (LPC) algorithm that is based on the code-excited linear prediction (CELP) method and has an algebraic structure. ACELP was developed in 1989 by the researchers at the Université de Sherbrooke in Canada. The ACELP method is widely employed in current speech coding standards such as AMR, EFR, AMR-WB (G.722.2), VMR-WB, EVRC, EVRC-B, SMV, TETRA, PCS 1900, MPEG-4 CELP and ITU-T G-series standards G.729, G.729.1 (first coding stage) and G.723.1. The ACELP algorithm is also used in the proprietary ACELP.net codec. Audible Inc. use a modified version for their speaking books. It is also used in conference-calling software, speech compression tools and has become one of the 3GPP formats. The ACELP patent expired in 2018 and is now royalty-free. Features The main advantage of ACE ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Call Transfer
A call transfer is a telecommunications mechanism that enables a user to relocate an existing telephone call to another phone or attendant console, using a transfer button or a switchhook flash and dialing the required location. The transferred call is either announced or unannounced. If the transferred call is announced, the desired party/extension is notified of the impending transfer. This is typically done by putting the caller on hold and dialing the desired party/extension; they are then notified and, if they choose to accept the call, it is transferred over to them. Other terms commonly used for an announced transfer include "attended", "consult", "full-consult", "supervised" and " conference" transfer. On the other hand, an unannounced transfer is self-explanatory: it is transferred without notifying the desired party/extension of the impending call. It is simply transferred to their line by way of a "transfer" key on the operator's phone or by keying in a string of digits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orange UK
Orange mobile UK was a mobile network operator and internet service provider in the United Kingdom, launched in 1994. It was once a constituent of the FTSE 100 Index but was purchased by France Télécom (now Orange S.A.) in 2000, which then adopted the Orange brand for all its other mobile communications activities. Orange UK merged with Deutsche Telekom's T-Mobile UK to form a joint venture, EE in 2010. EE continued to operate the Orange brand until February 2015, when new connections and upgrades on Orange tariffs were withdrawn. Existing Orange customers could continue on their plans until March 2019. History Background: 1990–1994 The inception of the Orange brand occurred in 1990 in the United Kingdom with the formation of Microtel Communications Ltd, a consortium initially formed by Pactel Corporation (American), British Aerospace, Millicom and Matra (French); and later wholly owned by BAe. In July 1991, the Hong Kong-based conglomerate Hutchison Whampoa, through a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Container Format (digital)
A container format (informally, sometimes called a wrapper) or metafile is a file format that allows multiple data streams to be embedded into a single file, usually along with metadata for identifying and further detailing those streams. Notable examples of container formats include archive files (such as the ZIP format) and formats used for multimedia playback (such as Matroska, MP4, and AVI). Among the earliest cross-platform container formats were Distinguished Encoding Rules and the 1985 Interchange File Format. Design Although containers may identify how data or metadata is encoded, they do not actually provide instructions about how to decode that data. A program that can open a container must also use an appropriate codec to decode its contents. If the program doesn't have the required algorithm, it can't use the contained data. In these cases, programs usually emit an error message that complains of a missing codec, which users may be able to acquire. Container fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Call Forwarding
Call forwarding, or call diversion, is a telephony feature of all telephone switching systems which redirects a telephone call to another destination, which may be, for example, a mobile or another telephone number where the desired called party is available. Call forwarding was invented by Ernest J. Bonanno. In North America, the forwarded line usually rings once to remind the customer using call forwarding that the call is being redirected. More consistently, the forwarded line indicates its condition by stutter dial tone. Call forwarding typically can redirect incoming calls to any other domestic telephone number, but the owner of the forwarded line must pay any toll charges for forwarded calls. Call forwarding is often enabled by dialing *72 followed by the telephone number to which calls should be forwarded. Once someone answers, call forwarding is in effect. If no one answers or the line is busy, the dialing sequence must be repeated to effect call forwarding. Call forwardin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Handover
In cellular telecommunications, handover, or handoff, is the process of transferring an ongoing call or data session from one channel connected to the core network to another channel. In satellite communications it is the process of transferring satellite control responsibility from one earth station to another without loss or interruption of service. Terminology American English uses the term ''handoff'', and this is most commonly used within some American organizations such as 3GPP2 and in American originated technologies such as CDMA2000. In British English the term ''handover'' is more common, and is used within international and European organisations such as ITU-T, IETF, ETSI and 3GPP, and standardised within European originated standards such as GSM and UMTS. The term handover is more common in academic research publications and literature, while handoff is slightly more common within the IEEE and ANSI organisations. Purpose In telecommunications there may be diffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
