Definitions of Audio and Video Formats
●nAVI Format: Abbreviation for newAVI. Developed by an underground group called ShadowRealm. Modified from Microsoft's ASF compression algorithm. Differs from ASF in streaming video; sacrifices ASF's 'streaming' characteristic for higher frame rates to improve clarity.
●DV-AVI Format: Digital Video Format. Proposed by Sony, Panasonic, JVC, etc., for consumer digital video. Modern digital camcorders record in this format. Transfers video to PC via IEEE 1394 (FireWire); edited video can be recorded back to camcorder. File extension is usually .avi, hence the name.
●MPEG Format: Moving Picture Expert Group. Formats like VCD, SVCD, DVD use this. MPEG is the international standard for compressing motion pictures using lossy compression to remove redundant information (e.g., subsequent frames share most data with previous ones). Max compression ratio ~200:1. Standards: MPEG-1, MPEG-2, MPEG-4 (MPEG-7, MPEG-21 in development).
●MPEG-1: Standardized 1992. Targets digital storage media below 1.5Mbps. VCD format. A 120-min movie compresses to ~1.2GB. Extensions: .mpg, .mlv, .mpe, .mpeg, .dat (VCD).
●MPEG-2: Standardized 1994. Targets broadcast-quality image & higher bitrates. Used for DVD/SVCD. Also HDTV, high-end video editing. A 120-min movie compresses to 4-8GB. Extensions: .mpg, .mpe, .mpeg, .m2v, .vob (DVD).
●MP3 (MPEG AUDIO LAYER 3): High compression audio format. Retains near-CD/MD quality despite ~10:1 compression (10 CD albums on one CD-R). Enables long playback. Obtained online or elsewhere.
●MPEG-4: Standardized 1998. Designed for streaming high-quality video over low bandwidth using frame reconstruction. Key attraction: Near-DVD quality at small file sizes. Additional features: Scalable bitrate, sprites, interactivity, DRM. Extensions: .asf, .mov, DivX .avi.
Note: Notice MPEG-3 is missing? MP3 audio uses MPEG-1 Layer 3 (MP3) encoding.
●DivX Format: Derived from MPEG-4. Known as DVDrip format. Combines MPEG-4 video compression with MP3/AC3 audio compression, plus external subtitles. Quality rivals DVD; size fraction of DVD. Demands modest hardware. Nicknamed 'DVD killer'.
●MOV Format: Developed by Apple. Default player: QuickTime. Good compression, quality. Key strength: Cross-platform (MacOS & Windows).
●ASF Format: Advanced Streaming Format. Microsoft's competitor to RealPlayer. Uses MPEG-4 compression; good compression/quality balance (high compression aids streaming, quality may suffer vs VCD). Playable with Windows Media Player.
●WMV Format: Windows Media Video. Microsoft's format for real-time online viewing. Advantages: Local/network playback, scalable media, component download, prioritized streaming, multi-language, environment independence, rich inter-stream relations, extensibility.
●RM Format: Real Media. RealNetworks' spec for audio/video compression. Players: RealPlayer/RealOne Player. RealMedia adapts compression to network speed for real-time streaming/playback at low bitrates. Key feature: Streaming playback without full download. Real Servers convert other formats to RM for delivery. RM vs ASF: RM often softer; ASF often clearer.
●RMVB Format: Upgraded RM (Real Media Variable Bitrate). Improvement: Replaces constant bitrate sampling with VBR—lower bitrate for static/slow scenes, higher bitrate for action. Balances quality & size better than constant bitrate RM. Compared to DVDrip, RMVB offers size advantage (e.g., 700MB DVD → ~400MB RMVB). Built-in subtitles; no plugins needed. Requires RealPlayer 8.0+ with RealVideo 9.0+ decoder.
●WAV Format: Waveform Audio File Format. Microsoft's uncompressed (usually) audio format. Earliest digital audio; widely supported on Windows. Supports compression algorithms, various bit depths/sample rates/channels. CD quality (44.1kHz, 16-bit) but huge file size—impractical for sharing.
●WMA Format: Windows Media Audio. Microsoft's format. Achieves higher compression (~1:18, half MP3 size) while maintaining quality. Crucial for limited storage (e.g., 32MB players). Supports DRM for copy protection, play time/count limits, even machine locking.
●3GP Format: 3GPP video encoding for 3G mobile networks. Most common video format on phones. Some smartphones play .rm files directly via RealPlayer. For other phones, 3GP is used. Many camera phones record in 3GP.
●DV-AVI Format: Digital Video Format. Proposed by Sony, Panasonic, JVC, etc., for consumer digital video. Modern digital camcorders record in this format. Transfers video to PC via IEEE 1394 (FireWire); edited video can be recorded back to camcorder. File extension is usually .avi, hence the name.
●MPEG Format: Moving Picture Expert Group. Formats like VCD, SVCD, DVD use this. MPEG is the international standard for compressing motion pictures using lossy compression to remove redundant information (e.g., subsequent frames share most data with previous ones). Max compression ratio ~200:1. Standards: MPEG-1, MPEG-2, MPEG-4 (MPEG-7, MPEG-21 in development).
●MPEG-1: Standardized 1992. Targets digital storage media below 1.5Mbps. VCD format. A 120-min movie compresses to ~1.2GB. Extensions: .mpg, .mlv, .mpe, .mpeg, .dat (VCD).
●MPEG-2: Standardized 1994. Targets broadcast-quality image & higher bitrates. Used for DVD/SVCD. Also HDTV, high-end video editing. A 120-min movie compresses to 4-8GB. Extensions: .mpg, .mpe, .mpeg, .m2v, .vob (DVD).
●MP3 (MPEG AUDIO LAYER 3): High compression audio format. Retains near-CD/MD quality despite ~10:1 compression (10 CD albums on one CD-R). Enables long playback. Obtained online or elsewhere.
●MPEG-4: Standardized 1998. Designed for streaming high-quality video over low bandwidth using frame reconstruction. Key attraction: Near-DVD quality at small file sizes. Additional features: Scalable bitrate, sprites, interactivity, DRM. Extensions: .asf, .mov, DivX .avi.
Note: Notice MPEG-3 is missing? MP3 audio uses MPEG-1 Layer 3 (MP3) encoding.
●DivX Format: Derived from MPEG-4. Known as DVDrip format. Combines MPEG-4 video compression with MP3/AC3 audio compression, plus external subtitles. Quality rivals DVD; size fraction of DVD. Demands modest hardware. Nicknamed 'DVD killer'.
●MOV Format: Developed by Apple. Default player: QuickTime. Good compression, quality. Key strength: Cross-platform (MacOS & Windows).
●ASF Format: Advanced Streaming Format. Microsoft's competitor to RealPlayer. Uses MPEG-4 compression; good compression/quality balance (high compression aids streaming, quality may suffer vs VCD). Playable with Windows Media Player.
●WMV Format: Windows Media Video. Microsoft's format for real-time online viewing. Advantages: Local/network playback, scalable media, component download, prioritized streaming, multi-language, environment independence, rich inter-stream relations, extensibility.
●RM Format: Real Media. RealNetworks' spec for audio/video compression. Players: RealPlayer/RealOne Player. RealMedia adapts compression to network speed for real-time streaming/playback at low bitrates. Key feature: Streaming playback without full download. Real Servers convert other formats to RM for delivery. RM vs ASF: RM often softer; ASF often clearer.
●RMVB Format: Upgraded RM (Real Media Variable Bitrate). Improvement: Replaces constant bitrate sampling with VBR—lower bitrate for static/slow scenes, higher bitrate for action. Balances quality & size better than constant bitrate RM. Compared to DVDrip, RMVB offers size advantage (e.g., 700MB DVD → ~400MB RMVB). Built-in subtitles; no plugins needed. Requires RealPlayer 8.0+ with RealVideo 9.0+ decoder.
●WAV Format: Waveform Audio File Format. Microsoft's uncompressed (usually) audio format. Earliest digital audio; widely supported on Windows. Supports compression algorithms, various bit depths/sample rates/channels. CD quality (44.1kHz, 16-bit) but huge file size—impractical for sharing.
●WMA Format: Windows Media Audio. Microsoft's format. Achieves higher compression (~1:18, half MP3 size) while maintaining quality. Crucial for limited storage (e.g., 32MB players). Supports DRM for copy protection, play time/count limits, even machine locking.
●3GP Format: 3GPP video encoding for 3G mobile networks. Most common video format on phones. Some smartphones play .rm files directly via RealPlayer. For other phones, 3GP is used. Many camera phones record in 3GP.