MPEG-4 is one of the latest video/audio compression method standardized by MPEG group, designed specially for low-bandwidth (less than 1.5MBit/sec bitrate) video/audio encoding purposes.
MPEG-4 is designed to deliver DVD-quality video (MPEG-2) at lower data rates and smaller file sizes.
It should be noted that unlike MPEG-1 and MPEG-2, the MPEG-4's predecessors, MPEG-4 itself isn't just one unified encoding mechanism, but rather a group name for several flavors of video and audio encoding methods that share certain same characteristics. These "flavors" are often referred either as "profiles" or "layers" in MPEG-4 compression scheme and each new profile should be backwards compliant to the older, "lower" versions of MPEG-4 in terms of playback capability.
Probably the best-known MPEG-4 video encoders are called DivX and XviD, which both are nowadays fully standard-compliant MPEG-4 encoders. The most common MPEG-4 profiles that both XviD and DivX use extensively are called "simple profile" and "advanced simple profile".
Beside those two standardized video encoding profiles, the MPEG-4 group has standardized several other profiles. The most important ones are H263+ (which is used widely in mobile phones, dubbed as 3GP) and H.264 (often also called as AVC or more technically known as MPEG-4 Part 10).
Since MPEG-4 is a container format, MPEG-4 files may contain any number of audio, video, and even subtitle streams, making it impossible to determine the type of streams in an MPEG-4 file based on its filename extension alone.
The official filename extension for MPEG-4 Part 14 files is .mp4, thus the container format is often referred to simply as MP4. However various file extensions are also commonly used to indicate the content inside the MP4 container:
- MPEG-4 files with audio and video generally use the standard .mp4 extension.
- Audio-only MPEG-4 files generally have a .m4a extension. This is especially true of non-protected content.
- MPEG-4 files with audio streams encrypted by FairPlay Digital Rights Management as sold through the iTunes Store use the .m4p extension.
- Audio book and podcast files, which also contain metadata including chapter markers, images, and hyperlinks, can use the extension .m4a, but more commonly use the .m4b extension. An .m4a audio file cannot "bookmark" (remember the last listening spot), whereas .m4b extension files can.
- Raw MPEG-4 Visual bitstreams are named .m4v.
- Mobile phones use 3GP, a simplified version of MPEG-4 Part 12 (a.k.a MPEG-4/JPEG2000 ISO Base Media file format), with the .3gp and .3g2 extensions. These files also store non-MPEG-4 data (H.263, AMR, TX3G).
The common but non-standard use of the extensions .m4a and .m4v is due to the popularity of Apple's iPod, iPhone, and iTunes Store, and Microsoft's Xbox 360 and Zune. Without mods, Nintendo's DSi and Sony's PSP can also play M4A.
0 - 9
A-GPS (Assisted GPS) | A2DP (Advanced Audio Distribution Profile) | AAC (Advanced Audio Coding) | Accelerometer | Airplane mode | Alarm Clock | Alphanumeric | AMOLED display (Active-matrix organic light-emitting diode) | Analog | Android | Antenna | APN (Access Point Name) | Apple iOS | Audio jack | Auto-focus | AVRCP (Audio/Video Remote Control Profile)
Calculator | Calendar | Call alerts | Calling Plan | Camera | Capacitive Touchscreen | Car Kit | Carrier | CDMA (Code-Division Multiple Access) | CDMA2000 | Cell | Chipset | cHTML (Compact HyperText Markup Language) | CIF (Common Intermediate Format) | Clamshell | CMOS (Complementary metal-oxidesemiconductor) | Color depth | Concatenated SMS | CPU (Central Processing Unit) | Crosstalk | CSTN (Color Super Twisted Nematic) | CTIA | Custom ringtones
D-Pad (Direction Pad) | DC-HSDPA (Dual Carrier or Dual Cell High-Speed Downlink Packet Access) | Digital Zoom | Display type | DLNA (Digital Living Network Alliance) | DNSe (Digital Natural Sound engine) | Downlink | DRM (Digital Rights Management) | Dual-band | Dual-Mode | Dual-SIM | DVB-H (Digital Video Broadcasting - Handheld) | Dynamic Memory
EDGE (Enhanced Data for Global Evolution) | EDR (Enhanced Data Rate) | EGPRS | EGSM (Extended GSM) | Email client | EMS (Enhanced Message Service) | EV-DO | EV-DV | Exchangeable covers | External Antenna Jack | External Display
FCC (Federal Communications Commission) | Feature Phone | Femtocell | Firefox OS | Firmware | Fixed-focus | Flash Memory | Flight mode | Flip-down phone | FM Radio | FM Transmitter | Form factor | FOTA (Firmware Over-The-Air) | FPS (Frames Per Second) | Frame Error Rate | Frequency | FTP (File Transfer Protocol)
H.263 | Half-QWERTY keyboard layout | Handwriting recognition | Haptics | Hot Spot | Hot Swap | HSCSD (High-Speed Circuit Switched Data) | HSDPA (High-Speed Downlink Packet Access) | HSDPA+ (High-Speed Downlink Packet Access Plus) | HSP (Headset Profile) | HSUPA (High-Speed Uplink Packet Access) | HTML (Hypertext Markup Language) | Hz (Hertz)
Land line | LCD (Liquid Crystal Display) | LED (Light-Emitting Diode) | Li-Ion (Lithium Ion) | Li-Polymer (Lithium Polymer) | LiMo OS | Linux | Location-Based Services (LBS) | Lock code | Long SMS | Long term evolution (LTE) | Loudspeaker
Macro | Maemo OS | mAh | Mass Storage mode | MB (Megabyte) | Mbps (Megabit per second) | MeeGo OS | Megapixel | Memory card slot | Memory effect | Messaging | MHz (Megahertz) | Micro USB | microSD | microSDHC | Microsoft Exchange (Server) | MIDI (Musical Instrument Digital Interface) | MIDP (Mobile Information Device Profile) | Mil-Spec (MIL-STD) | Mini-USB | miniSD | MMC | MMCmobile | MMS (Multimedia Messaging Service) | Mobile games | Mobile IM (Instant Messaging) | Mobile WiMAX | Modem | Monochrome | MP3 (MPEG Layer 3) | MPEG (Motion Picture Experts Group) | MPEG-4 video | Multitouch input method | Music playback time (battery life) | Music Player
Packet Data | Pager | PC Sync | PCS (Personal Communications Service) | PDA (Personal Digital Assistant) | Phone Book Access (PBA) | Phonebook | PIM (Personal Information Manager/Management) | PIN code (Personal Identification Number) | Pixel | Pixel density (PPI) | Polyphonic ringtones | POP3 (Post Office Protocol) | Port | Predictive text input | PTT (Push-To-Talk) | PUK Code (PIN UnlocK Code) | Push
RAM (Random-Access Memory) | RBDS (Radio Broadcast Data System) | RDS (Radio Data System) | Resistive touchscreen | Resolution | Ringer ID | Ringing profiles | Ringtone | Roaming | ROM (Read-Only Memory) | RS-MMC (Reduced-Size Multi Media Card) | RSA (Rural Service Area) | RSS (Rich Site Summary) | Ruggedized (Rugged)
S60 user interface | SAP (SIM Access Profile) | SAR (Specific absorption rate) | Screen protection | SD (Secure Digital) | Secondary camera | Sensors | Side Keys | SIM | SIM lock | Single-Band | Skin | Smartphone | SMIL | SMS (Short Messaging Service) | SNS (Social network service) | Soft keys | Soft Reset | Speed Dial | Stand-by time (battery life) | Stereo Speakers | Streaming Video | Stylus | Sub-QCIF | SVGA | Symbian | SyncML
Talk time (battery life) | TCP/IP | TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) | TEST | Tethering | Text messaging (texting) | TFD (Thin Film Diode) | TFT (Thin Film Transistor) | Theme | To-Do list | Touchscreen | Trackball | Transflash | Transflective | Tri-band