vido: latin for "I see". from "a video tutorial" (http://www.gekco.com/vidprmr.htm) black and white, 252.5 vertical lines left-to-right, top-to-bottom, interleaved on 2nd pass US color television 1953 NTSC (National Television System Committee) standard 3 electron beams (r,g,b) from en.wikipedia.org/wiki/Video encoding formats: NTSC (US, Japan) analog signal 4:3 aspect ratio 29.97 interlaced frames per second each 480 vertical lines (out of a total of 525; others for sync and other data such as captions) intelaced means odd lines drawn on odd times, even lines on even times, at 59.94 Hz (i.e. 60Hz/1.001). (This frequency was convenient for early systems since it could just use AC current in US.) compatible with older black/white; color transmitted on "chrominance subcarrier" 6MHz bandwith, AM signal; audio is FM "Video professionals and television engineers do not hold NTSC video in high regard, joking that the abbreviation stands for "Never Twice the Same Color" or "Never Tested Since Christ". For one, the interlaced picture (drawing every other horizontal line of video in one pass, and filling in the others in the second) complicates editing video. Additionally, radio interference tends to degrade an NTSC picture, so the picture often loses its color balance by the time the viewer receives it (this necessitates the inclusion of a "tone" or "hue" control on NTSC sets, which is not necessary on PAL or SECAM systems). And finally, some complain that the 525 line resolution of NTSC results in a lower quality image than the hardware is capable of." PAL (Europe) 625 line, 25 Hz (where 50Hz AC is used); noticeable more flicker. SECAM (France, others) broadcast and inter-connection signal standards RF (VHF : 30MHz (10m) - 300MHz (1m) ; "Very High Frequency") composite video : format before modulated onto an RF carrier YUV (Y = luminance, UV = color information) what you get from the yellow jack of a VCR; red/white are stereo sound (for video games, an RF modulator often used to send the composite signal to channel 3 or 4. This means the vido signal has RF (1) added in and then (2) taken out by the TV. Can you say "extra noise"?) component video RGB or YUV (eg. Y, R-Y, B-Y) in three separate wires, sometimes referred to as 4:2:2 in terms of allocated bits (4 for Y, 2 for U,V on even lines, 2 for UV on odd lines) DVD's often use 4:2:0, with color for odd lines interpolated. S-Video between composite and component; uses 2 signals Y/C. "The luminance is effectively a black-and-white TV signal with the timing of a color composite video signal." "Because the luminance is on a separate wire, it doesn't need to be low-pass filtered to prevent crosstalk between high-freq luminance and color subcarrier." Typically 4-pin mini-DIN with 75ohm termination impedence RBG -------------------------- analog videotape VHS 250 lines vertical; 3MHz horizontal resolution -------------------------- digital television: MPEG-2 data stream standard. broadcast as ATSC (US, Canada) "Advanced Television Systems Committee" DVB-T (everywhere else) "Digital Video Broadcast - Terrestial" commercial DVD format (with some modifications) has (a) video w/ timestamps, (b) audio w/ timestamps 25 (CCIR, europe) or 29.97 (FCC, US) frames per second with sound video is YUV in "macroblocks", each with four 8x8 luminance blocks. Commonly 4:2:0 has one chrominance block per each channel for a total of 6 blocks per macroblock. three ways of encoding picture: intra-coded (I picture) 8x8 DCT, zigzag ordered, quantized, run-length coded, and huffman coded (like JPEG) (This compresses for spacial redundancy, basically) forward predictive (P picture) differences from previous image are stored; typically 10% size of I's, but can take 3 times longer than I to encode (can be an issue with live broadcasts) bidirectional predictive (B picture) differences from previous and next stored; typically 2% size of I's. GOP is a "Group of Pictures". A typical structure is 12 or 15 frames long, something like display order: B1 B2 I3 B4 B5 P6 B7 B8 P9 B10 B11 P12 bitstream order: I3 B1 B2 P6 B4 B5 P9 B7 B8 P12 B10 B11 DVD bitrate is 10.4 Mbits/sec MPEG IMG Professional videotape is up to 50 Mbit/sec ----------------------- film : usually 24 frames per second 70mm is also shot today 35mm * basic film format for both still and motion pictures * unchanged since 1889; has holes (perforations) along edges * various ways to put images on film : * classic movie : 4 perforations / frame, vertically, aspect ratio is 4:3. * still : frame horizontal, 8 perf / frame * vistavision : like sill, 1.67 aspect ratio, never really caught on * cinemescope : (anamorphic) image compressed horizontally to fit on on the film horizontally, even though wide on screen with aspect ratio of 2.35 * today most are shot w/ 4 perf/frame and cropped top/bottom to get 1.85 or 1.67 aspect ratio * or even 3-perf with 16:9 HDTV format audio for films is now stored several ways, including SDDS (two strips beyond perforations) and DTS (on a separte CD which is synced to the film) ======================================================= MPEG-2 compression tutorial : http://www.bbc.co.uk/rd/pubs/papers/paper_14/paper_14.html (copied to cs/docs/mpeg2/) "MPEG-2 aims to be a generic video coding system supporting a diverse range of applications." raw bit rate is something like bit rate (color 4:2:0, 1.5 aspect ratio) (720x480 pixels ) x 30 frames/sec x ( 8 greyscale bits + 4 color bits) = 118 Mbits/sec MPEG-2 compresses this to about 3-15 Mbps (standard TV). HDTV can go as high as 15-30Mbps. ========================================================== video file comparison http://www.dvdrhelp.com/xvcd.htm#comp ========================================================== software * open source Mac video : http://www.apple.com/downloads/macosx/video/ (also various other Mac OS software) * iStopMotion - animation, eh? * DivXRay 3.0 (DVD -> MPEG4 conversion with cd writer) * QuickMix 1.2 - editing? * 3ivx D4 (DivX, Xvid quicktime/mp4) http://www.3ivx.com/download/macos.html * DivX (decoder only as quicktime codec; encoder not on Mac OS yet) http://www.divx.com/divx/mac * VLC (streaming) http://www.videolan.og/vlc/download-macosx.html * Motion - apple commercial text/graphics/video "behaviours" $300, due for summer 2004 release * Cleaner5 - Mac (video encoding) http://www.discreet.com/products/cleaner/cleaner6/ * ffmpegX (open source video/audio encoder for Mac OS X) http://homepage.mac.com/major4/ * MPlayer (opensource, multiplatform 3ivx, DivX, ... player) * Xiph.org (http://www.xiph.org/) - Ogg Vorbis and Ogg Theoro (open source audio and video formats) * Ripping: afterdawn.com DVDBackup (decode) DVD2oneX (compress) Toast (DVD burning) MacTheRipper (open source Mac dvd ripper - duh) front end for dvdbackup http://www.wormintheapple.gr/macdvd/mtr.html "Any copyright infringing activity you choose to perpetrate using this application is illegal, wrong, and beyond our control." OSex DVD Decrypter DVD2AVI, DVD2SVCD dvd::rip (opensource linux) DVDx Eazy VCD ImTOO DVD Ripper v2.0.9 www.imtoo.net/dvd-ripper.html (windows, $35, "download now for free" - demo, I guess) Gordian Knot Rip Pack (open source, windows) http://gordianknot.sourceforge.net/