Video Glossary

• AVI
  Audio Video Interleaved - A multimedia file format for storing sound and moving pictures in RIFF format developed by Microsoft. An AVI file can use different codecs and formats so there is no set format for an AVI file unlike for example standard VCD video which sets a standard for resolution, bitrates, and codecs used.
• MPEG-1
  An ISO/IEC (International Organization for Standardization/ International Electrotechnical Commission) standard for medium quality and medium bitrate video and audio compression. It allows video to be compressed by the ratios in the range of 50:1 to 100:1, depending on image sequence type and desired quality. The encoded data rate is targeted at 1.5Mb/s - this was a reasonable transfer rate of a double-speed CD-ROM player (including audio and video). VHS-quality playback is expected from this level of compression. The Motion Picture Expert Group (MPEG) also established the MPEG-2 standard for high-quality video playback at a higher data rates. MPEG-1 is used in encoding video for VCD.

• MPEG-2
  An encoding standard designed as an extension of the MPEG-1 international standard for digital compression of audio and video signals. MPEG-1 was designed to code progressively scanned video at bit rates up to about 1.5 Mbit/s for applications such as CD-i. MPEG-2 is directed at broadcast formats at higher data rates; it provides increased support for efficiently coding interlaced video, supports a wide range of bit rates and provides for multichannel surround sound coding such as PCM, Dolby Digital, DTS and MPEG audio.
• MPEG / VCD / SVCD/ DVD
  MPEG is the dominant file format used to create VCD, SVCD and DVD. This high quality compressed format can be used across all platforms. VCD, SVCD and DVDs accept MPEG files that conform to their respective standards. MPEG files differ in many parameters that characterizes the MPEG format.
  The table below lists down the format in which MPEG files are made by Video Workshop depending on the type of video disc.

  Video Disc			MPEG Format (Standard)
  Disc Format	Picture Standard	Disc Type	MPEG Type	Dimension (pixels)	Frame Rate (FPS)	Video Bitrate (Kbps)	Audio Bitrate (Kbps)
  VCD	NTSC	CD	MPEG 1	352 x 240	29.97	1152	224
  VCD	PAL	CD	MPEG 1	352 x 288	25	1152	224
  SVCD	NTSC	CD	MPEG 2	480 x 480	29.97	2500	192
  SVCD	PAL	CD	MPEG 2	480 x 576	25	2500	192
  DVD	NTSC	DVD	MPEG 2	720 x 480	29.97	6000	224
  DVD	PAL	DVD	MPEG 2	720 x 576	25	6000	224

• NTSC
  Abbreviation of National Television Standards Committee. The NTSC is responsible for setting television and video standards in the United States (in Europe and other parts of the world, the dominant television standards are PAL and SECAM). The NTSC standard for television defines a composite video signal with a refresh rate of 60 fields (half-frames interlaced) per second. Each frame contains 525 lines and can contain 16 million different colors. The resolution of an NTSC VCD is 352x240 pixels, an NTSC SVCD is 480x480, and an NTSC full D1 DVD is 704 or 720 x 480.
• PAL
  Short for Phase Alternating Line, the dominant television standard in Europe. The United States uses a different standard, NTSC. PAL delivers 625 lines at 50 fields (half-frames interlaced) per second. The resolution of a PAL VCD is 352x288 pixels, a PAL SVCD is 480x576, and a PAL full D1 DVD is 704 or 720 x 576.
• ASF
  Advanced Streaming Format (ASF): This file format stores audio and video information, and it is specially designed to run on networks like the Internet. This file format is a highly flexible and compressed format that contains streaming audio, video, slide shows, and synchronized events. When you use .asf files, content is delivered to you as a continuous flow of data. You no longer have to wait for your audio and video files to fully download before you start to view them. When an AVI file is compressed and converted to an .asf file, the file begins playing after only a few seconds. The file can be unlimited in length and can run over Internet bandwidths.
• MOV,QT (Quick Time)
  A digital video Format standard developed by Apple Computer for Macintosh (Mac OS) and Windows operating systems.
• MP4
  A container format allows you to combine different multimedia streams (most of the time audio and video) into one single file.
  Multimedia containers are for example the well known AVI (.avi), MPEG (.mpg, .mpeg), Matroska (.mkv, .mka), OGM (.ogm), Quicktime (.mov) or Realmedia (.rm, .rmvb)
  MP4 is the global file extension for the official container format defined in the MPEG-4 standard (ISO 14496-14)
  MP4 is streamable and supports all kinds of multimedia content (multiple audio-, video-, subtitlestreams, pictures, variable-framerates, -bitrates, -samplerates...) and advanced content (officially called "Rich Media" or "BIFS") like 2D and 3D animated graphics, user interactivity, DVD-like menus... - next to nothing handled by the often used AVI
• 3GP
  The mpeg4 based video format used in mobile terminals, like cell phones.
• MP3
  MP3 is an acronym for MPEG-1 (or MPEG-2) Layer 3 audio encoding (it is not an acronym for MPEG3). MP3 is a popular compression format used for audio files on computers and portable devices.
  The compression in MP3 works on the basis of a "psychoacoustic model" which means that parts of the audio that human ears cannot detect are discarded by the encoder. Although this is a LOSSY process, it can yield very high quality audio files are relatively high compression rates.
  A typical MP3 file encoded at 128 kbit/s (12:1 compression) is near CD quality.
• Wave
  Wave is the standard form for uncompressed audio on a PC. Since a wave file is uncompressed data - as close a copy to the original analog data as possible - it is therefore much larger than the same file would be in a compressed format such as mp3 or RealAudio. Audio CDs store their audio in, essentially, the wave format. Your audio will need to be in this format in order to be edited using a wave editor, or burned to an audio CD that will play in your home stereo.
• Sample Rate
  The sample rate of an audio recording partially determines the overall sound quality. In the recording process, audio samples are saved to memory or disk; the rate each sample of audio input is recorded per second is the sample rate. The sample rate is measured in Hertz (Hz - cycles per second) and Kilohertz (kHz - thousand cycles per second).
• CD quality audio has a sample rate of 44100Hz, 16-bit (resolution) and stereo (channels). The most common sample rates are 11, 22 and 44kHz, with most recording software supporting sample rates from 6kHz up to 192kHz. Like early footage filmed at a low frame rate looks flickered and robotic, the quality of an audio recording decreases as the sample rate is lowered. For audio recordings destined to be encoded to MP3, 22kHz is considered acceptable.
• Bit Rate
  Bit rate is the amount of information (bits) transferred in a second ('bps' is the abbreviation of bits-per-second). Bitrate or Bit Rate is the average number of bits that one second of video or audio data will consume. Higher bitrate means bigger file size and generally better video or audio quality while lower bitrate means lower file size but worse video or audio quality. Some bitrate examples in common video and audio files:
  MP3 about 128 kbps (kilobits per second)
  VCD about 1374 kbps
  DVD about 4500 kbps
  DV about 25 Mbps (megabits per second).
• bps
  Bits per second. A unit of data rate
• fps
  Frames per second. A measure of the rate at which pictures are shown for a motion video image. In NTSC and PAL video, each frame is made up of two interlaced fields.
• Codec
  An acronym for "compression/deccompression", a codec is an algorithm or specialized computer program that encodes or reduces the number of bytes consumed by large files and programs. Files encoded with a specific codec require the same codec for decoding. Some codecs you may encounter in computer video production are Divx, MPEG-1, MPEG-2, Xivd, DV type 1 and type 2 for video and MP3 for audio.