Difference between revisions of "Glossary of terms"

Latest revision as of 21:35, 12 August 2012

These are some terms that you'll see in the Knowledge Base:

• 2D, 3D: For our purposes, a heuristic for the presence of blinking. It is much more likely for a 2D game than a 3D game to have F1 blinking effects. Low quality versions of such games are encoded at F3 instead of F2 so that the blinking is still apparent.
• AAC, AVC: Advanced Audio Codec and Advanced Video Codec. Used in MP4 movies on SDA.
• Anri-chan: SDA's video encoding software.
• AVI: A movie container format used in the past by SDA. Contains DivX or XviD video and MP3 audio.
• AviSynth: A scripting tool for editing video. Anri-chan uses it for movie production.
• Blinking: Before the 32-bit era, consoles had no ability to make sprites translucent (partially transparent). Games would try to replicate the effect by flashing the sprite visible and invisible on alternating frames, or by doing similar things to produce other effects. Blinking is an issue when the frame rate is halved to F2 as the sprite will then be constantly visible or invisible. See FDP, 2D, 3D.
• Capture: To record with a capture card.
• Codec: A way to compress video or audio. If video was uncompressed, it would be far too massive to transmit over the Internet; thus, it is compressed with a codec. To be played back, it must be decoded with the same codec.
• D1, D4, etc: Video dimensions. D1 (high resolution) in NTSC is 720x480 (DVD) or 640x480 (video file); PAL D1 is 720x576 (DVD) or 704x576 (video file). D4 (low resolution) in NTSC is 320x240; PAL is 352x288. D2 and D3 are only relevant to DVD output and are not discussed on this site.
• Deinterlace: Movies on SDA use progressive scan, but most video captured from TV equipment is interlaced. Deinterlacing is the process to turn interlaced video into progressive video. If the whole video can be made by only discarding parts of the video (LQ/MQ), the process is quick. Otherwise (HQ/IQ) the video must be analysed to recreate the missing parts of the picture, which is very slow.
• DivX: An older video codec. Used in AVI movies. Also see "XviD".
• Encode: To compress with a codec.
• F1, F2, F3: Video framerates. The number is the denominator of a fraction whose numerator is always 1. Thus, F1 is full framerate, F2 is half framerate, and F3 is third framerate. F1, F2 and F3 in NTSC are 59.94, 29.97 and 19.98 FPS, respectively, while in PAL they are 50, 25 and 50/3 (~16.666667) FPS, respectively.
• FDP: Framerate Decimation Paradigm. See 2D, 3D.
• Field: An interlaced frame contains half the picture for each of two consecutive frames of video. Each normal frame's share of the interlaced frame is called a field. If the frame has 480 rows of pixels, the first field will be rows 1,3,5,...,479 and the second field will be rows 2,4,6,...,480. To separate fields means to take each set of fields and put them in their own individual frames.
• Field Blending: A cheap method of deinterlacing in which the two fields in a frame are blurred together. Unacceptable for publication at SDA.
• Finalize: A process done on DVD recorders that allows discs to be used on other equipment. Once you have finalized a disc, you cannot put anything else on it. The exception is DVD-RW, which you must format in order to write to once it has been finalized. Finalization must be done on the DVD recorder that recorded the disc.
• Frame: Rather than using true motion, videos use frames, where slightly different images are shown rapidly to create the illusion of motion. Each image is called a frame.
• Framerate: The rate at which frames are displayed. This is written as "x FPS," where x is the number of frames displayed each second.
• H.264: An advanced video codec (AVC). Used in MP4 movies on SDA.
• HQ: High quality. 2Mb/s video, 128Kb/s audio, D1, F1
• IQ: Insane quality. 5Mb/s video, up to 320Kb/s audio, up to 1368x768, F1
• Interlaced: When a video signal comes one field at a time - to produce two frames "laced" together into one - it is said to be interlaced. Interlacing is used in TV video to halve the amount of bandwidth used in the video signal, while only slightly harming the viewing experience. Also see "Field".
• LQ: Low quality. 128Kb/s video, 64Kb/s audio, D4, F2/3
• MeGUI: A tool used to encode video and audio.
• MQ: Medium quality (same as normal quality). 512Kb/s video, 64Kb/s audio, D1/4, F1/2/3
• MP3: An audio codec. Used in AVI movies on SDA in the past.
• MP4: SDA's current video container format. Currently contains H.264 video and AAC audio.
• MP4Box: A command-line application for working with MP4 files. Anri-chan uses it to mux together the video and audio, but it has a lot of uses (e.g. splitting movies into 10-minute chunks for YouTube). There is a Windows GUI for it called YAMB.
• mvbob: An advanced deinterlacing filter used by Anri-chan for HQ and higher movies. "Bob" filters (including LeakKernelBob, which is a quicker filter for casual use) are required to do the video rebuilding work needed to maintain the resolution and/or the frame rate of interlaced video. Because of the complexity of the work, mvbob is by far the slowest part of the video processing.
• nate: The person who handles capturing and encoding runs for SDA, as well as many other very important tasks.
• ND, NDA: Nero Digital Audio, the implementation of AAC used by SDA.
• NMF: New Master File. Refers to an intermediate source video file in the encoding process, usually one saved after deinterlacing (to avoid slow deinterlacing during each pass for each quality of output, and to allow it to use multiple CPU cores). To maintain the video quality of the source video, the compression (if any) is lossless, meaning the NMF has a very, very high bitrate.
• NQ: Normal quality (same as medium quality).
• Progressive Scan: When a video signal comes whole frames at once, it is said to be progressive scan.
• StatID: Station ID. A title card appearing before and after a video posted on SDA that contains the SDA logo, the runner's name, the game, type of run and official time. It is exactly 5 seconds long.
• Transcode: To convert from one file format to another. Similar to "Encode", except the source is usually already encoded.
• VirtualDub: A Windows tool used to encode video and audio.
• VirtualDub Mod: A modification to VirtualDub that is superior in some aspects but inferior in others.
• x264: The implementation of H.264 used by SDA.
• XQ: X-TREME quality. 10Mb/s video, up to 320Kb/s audio, any resolution, F1.
• Xvid: DivX spelled backwards. Xvid is open source and generally produces better quality video than DivX while remaining fully compatible. Used in AVI movies on SDA in the past.