MMS is the evolution of Short Message Service (SMS, which is a text-only messaging technology for mobile networks). Its main standardization effort is done by 3GPP, 3GPP2 and Open Mobile Alliance (OMA). It is mainly deployed in cellular networks along with other messaging systems like SMS, Mobile Instant Messaging and Mobile E-mail. Multimedia Messaging Service (MMS) is a standard for telephony messaging systems that allows sending messages that include multimedia objects (images, audio, video, rich text) and not just text as in Short Message Service (SMS). 3g2)īoth are based on MPEG-4 and H263 video, and AAC or AMR audio. * 3GPP2 (for CDMA Based Phones, may have filename extension. * 3GPP (for GSM Based Phones, may have filename extension. There are two different standards for this format: It also contains descriptions of image sizes and bitrate. A 3GP file is always big-endian, storing and transferring the most significant bytes first. It stores video streams as MPEG-4 Part 2 or H.263 or MPEG-4 Part 10 (AVC/H.264), and audio streams as AMR-NB, AMR-WB, AMR-WB+ or AAC-LC.
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* MP3 CD Players - Portable CD players that can decode and play MP3 audio files stored on CDs.ģGP is a multimedia container format defined by the Third Generation Partnership Project (3GPP) for use on 3G mobile phones.ģGP is a simplified version of the MPEG-4 Part 14 (MP4) container format, designed to decrease storage and bandwidth requirements in order to accommodate mobile phones. Such multi-media devices are usually called Portable Media Players or Personal Media Players (PMPs). Because of the storage capacity, devices that also display video and pictures are often hard disk drive based. At typical encoding rates, this means that thousands of songs - perhaps an entire music collection - can be stored on one player. These players have higher capacities currently ranging up to 160GB. * Hard drive-based Players or Digital Jukeboxes - Devices that read digital audio files from a hard disk drive (HDD). Basic MP3 player functions are commonly integrated into USB flash drives. Because they are solid state and do not have moving parts they require less battery power and may be more resilient to hazards such as dropping or fragmentation than hard disk-based players. Due to technological advancements in flash memory, these originally low-storage devices are now available commercially ranging up to 16GB. * Flash-based Players - These are non mechanical solid state devices that hold digital audio files on internal flash memory or removable flash media called memory cards. Listening to music stored on DAPs is typically done through earphones, but external speakers and docking stations are also available.ĭigital audio players are generally categorized by storage media: Most DAPs are powered by rechargeable batteries, some of which are not user replaceable. More commonly referred to as an MP3 player, a digital audio player or "DAP" is a portable, handheld digital music player that stores, organizes and plays MP3 and often other audio files.
Similar principles are used by JPEG, an image compression format. It provides a representation of pulse-code modulation - encoded audio in much less space than straightforward methods, by using psychoacoustic models to discard components less audible to human hearing, and recording the remaining information in an efficient manner. The compression removes certain parts of sound that are outside the hearing range of most people. It was invented by a team of European engineers at Philips, CCETT (Centre commun d'études de télévision et télécommunications), IRT and Fraunhofer Society, who worked in the framework of the EUREKA 147 DAB digital radio research program, and it became an ISO/IEC standard in 1991. It uses a lossy compression algorithm that is designed to greatly reduce the amount of data required to represent the audio recording, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners.
MPEG-1 Audio Layer 3, more commonly referred to as MP3, is an audio encoding format.
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