|
3G2
3GP (3GPP file format) is a multimedia container format defined by the Third Generation Partnership Project (3GPP) for 3G UMTS multimedia services. It is used on 3G mobile phones but can also be played on some 2G and 4G phones. 3G2 (3GPP2 file format) is a multimedia container format defined by the 3GPP2 for 3G CDMA2000 multimedia services. It is very similar to the 3GP file format but consumes less space & bandwidth also has some extensions and limitations in comparison to 3GP. Specifications 3GP is defined in the ETSI 3GPP technical specification.ETSI 3GP3GPP TS 26.244; Transparent end-to-end packet switched streaming service (PSS); 3GPP file format (3GP)Retrieved on 2009-06-02. 3GP is a required file format for video and associated speech/audio media types and timed text in ETSI 3GPP technical specifications for IP Multimedia Subsystem (IMS), Multimedia Messaging Service (MMS), Multimedia Broadcast/Multicast Service (MBMS) and Transparent end-to-end Packet-switched St ... [...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] |
MPEG-4 Part 12
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. History Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selectable Mode Vocoder
Selectable Mode Vocoder (SMV) is variable bitrate speech coding standard used in CDMA2000 networks. SMV provides multiple modes of operation that are selected based on input speech characteristics. The SMV for Wideband CDMA is based on 4 codecs: full rate at 8.5 kbit/s, half rate at 4 kbit/s, quarter rate at 2 kbit/s, and eighth rate at 800 bit/s. The full rate and half rate are based on the CELP algorithm that is based on a combined closed-loop-open-loop-analysis (COLA). In SMV the signal frames are first classified as: * Silence/Background noise * Non-stationary unvoiced * Stationary unvoiced * Onset * Non-stationary voiced * Stationary voiced The algorithm includes voice activity detection (VAD) followed by an elaborate frame classification scheme. Silence/background noise and stationary unvoiced frames are represented by spectrum-modulated noise and coded at 1/4 or 1/8 rate. The SMV uses 4 subframes for full rate and two/three subframes for half rate. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EVRC
Enhanced Variable Rate CODEC (EVRC) is a speech codec used in CDMA networks. It was developed in 1995 to replace the QCELP vocoder which used more bandwidth on the carrier's network, thus EVRC's primary goal was to offer the mobile carriers more capacity on their networks while not increasing the amount of bandwidth or wireless spectrum needed. EVRC uses RCELP technology. EVRC compresses each 20 milliseconds of 8000 Hz, 16-bit sampled speech input into output frames of one of three different sizes: full rate – 171 bits (8.55 kbit/s), half rate – 80 bits (4.0 kbit/s), eighth rate – 16 bits (0.8 kbit/s). A quarter rate was not included in the original EVRC specification and eventually became part of EVRC-B. EVRC was replaced by SMV. Recently, however, SMV itself has been replaced by the new CDMA2000 4GV codecs. 4GV is the next generation 3GPP2 The 3rd Generation Partnership Project 2 (3GPP2) is a collaboration between telecommunications associations to make a global ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HE-AAC
High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio defined as an MPEG-4 Audio profile in ISO/IEC 14496–3. It is an extension of Low Complexity AAC (AAC-LC) optimized for low-bitrate applications such as streaming audio. The usage profile HE-AAC v1 uses spectral band replication (SBR) to enhance the modified discrete cosine transform (MDCT) compression efficiency in the frequency domain. The usage profile HE-AAC v2 couples SBR with Parametric Stereo (PS) to further enhance the compression efficiency of stereo signals. HE-AAC is used in digital radio standards like HD Radio, DAB+ and Digital Radio Mondiale. History The progenitor of HE-AAC was developed by Coding Technologies by combining MPEG-2 AAC-LC with a proprietary mechanism for spectral band replication (SBR), to be used by XM Radio for their satellite radio service. Subsequently, Coding Technologies submitted their SBR mechanism to MPEG as a basis of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Audio Coding
Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves higher sound quality than MP3 encoders at the same bit rate. AAC has been standardized by ISO and IEC as part of the MPEG-2 and MPEG-4 specifications.ISO (2006ISO/IEC 13818-7:2006 - Information technology -- Generic coding of moving pictures and associated audio information -- Part 7: Advanced Audio Coding (AAC), Retrieved on 2009-08-06ISO (2006, Retrieved on 2009-08-06 Part of AAC, HE-AAC ("AAC+"), is part of MPEG-4 Audio and is adopted into digital radio standards DAB+ and Digital Radio Mondiale, and mobile television standards DVB-H and ATSC-M/H. AAC supports inclusion of 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 16 low frequency effects ( LFE, limited to 120 Hz) channels, up to 16 "coupling" or dialog channels, and up to 16 data streams. The quality for stereo is satisf ... [...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] |
MPEG-4 Part 2
MPEG-4 Part 2, MPEG-4 Visual (formally ISO/IEC 14496-2) is a video compression format developed by the Moving Picture Experts Group (MPEG). It belongs to the MPEG-4 ISO/IEC standards. It uses block-wise motion compensation and a discrete cosine transform (DCT), similar to previous standards such as MPEG-1 Part 2 and H.262/MPEG-2 Part 2. Several popular codecs including DivX, Xvid, and Nero Digital implement this standard. Note that MPEG-4 Part 10 defines a different format from MPEG-4 Part 2 and should not be confused with it. MPEG-4 Part 10 is commonly referred to as H.264 or AVC, and was jointly developed by ITU-T and MPEG. MPEG-4 Part 2 is H.263 compatible in the sense that a basic H.263 bitstream is correctly decoded by an MPEG-4 Video decoder. (MPEG-4 Video decoder is natively capable of decoding a basic form of H.263.) In MPEG-4 Visual, there are two types of video object layers: the video object layer that provides full MPEG-4 functionality, and a reduced functionality ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QCELP
Qualcomm code-excited linear prediction (QCELP), also known as Qualcomm PureVoice, is a speech codec developed in 1994 by Qualcomm to increase the speech quality of the IS-96A codec earlier used in CDMA networks. It was later replaced with EVRC since it provides better speech quality with fewer bits. The two versions, ''QCELP8'' and ''QCELP13'', operate at 8 and 13 kilobits per second (Kbit/s) respectively. In CDMA systems, a QCELP vocoder A vocoder (, a portmanteau of ''voice'' and ''encoder'') is a category of speech coding that analyzes and synthesizes the human voice signal for audio data compression, multiplexing, voice encryption or voice transformation. The vocoder was ... converts a sound signal into a signal transmissible within a circuit. In wired systems, voice signals are generally sampled at 8 kHz (that is, 8,000 sample values per second) and then encoded by 8-bit quantization for each sample value. Such a system transmits at 64 kbit/s, an expensive rat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endianness
In computing, endianness, also known as byte sex, is the order or sequence of bytes of a word of digital data in computer memory. Endianness is primarily expressed as big-endian (BE) or little-endian (LE). A big-endian system stores the most significant byte of a word at the smallest memory address and the least significant byte at the largest. A little-endian system, in contrast, stores the least-significant byte at the smallest address. Bi-endianness is a feature supported by numerous computer architectures that feature switchable endianness in data fetches and stores or for instruction fetches. Other orderings are generically called middle-endian or mixed-endian. Endianness may also be used to describe the order in which the bits are transmitted over a communication channel, e.g., big-endian in a communications channel transmits the most significant bits first. Bit-endianness is seldom used in other contexts. Etymology Danny Cohen introduced the terms ''big-endian'' a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
