Multimedia. Sound. Panorama des médias sociaux. Aviez-vous remarqué que le terme « web 2.0 » n’est plus à la mode ? Il faut dire qu’à force de nous survendre du « 2.0 » à toutes les occasions, le concept fini par lasser. Maintenant, on parle de médias sociaux. Car avec un nombre de services en ligne toujours plus important, des concepts tous plus sophistiqués, des copies, des mashups dans tous les sens… il devenait difficile de s’y retrouve. Voilà pourquoi il était important de morceler cette grosse bouillabaisse qu’était devenu le web 2.0 en plusieurs sous-concepts pour en faciliter la compréhension. De ce morcellement sont nés le social shopping, l’entreprise 2.0, les médias sociaux et bien d’autres encore. Mais a-t-on déjà pris le temps de bien définir ce qu’étaient les médias sociaux ?
Publions, partageons, sociabilisons ! Dans « médias sociaux » il y a « média« , ce qui veut dire que les médias sociaux sont des supports numériques à une prise de parole ou une publication. Une infinité d’outils et de services Ouf ! Quels KPIs ? AdHoc-DigitalCommunicationArts. Basics of Video. Basics of Video Analog video is represented as a continuous (time varying) signal. Digital video is represented as a sequence of digital images. Types of Color Video Signals Component video -- each primary is sent as a separate video signal. Analog Video The following figures are from A.M.
NTSC Video 525 scan lines per frame, 30 frames per second (or be exact, 29.97 fps, 33.37 msec/frame) Interlaced, each frame is divided into 2 fields, 262.5 lines/field 20 lines reserved for control information at the beginning of each field So a maximum of 485 lines of visible data Laserdisc and S-VHS have actual resolution of ~420 lines Ordinary TV -- ~320 lines Each line takes 63.5 microseconds to scan. Digital Video Rasters Color representation: NTSC uses YIQ color model. PAL Video 625 scan lines per frame, 25 frames per second (40 msec/frame) Interlaced, each frame is divided into 2 fields, 312.5 lines/field Uses YUV color model Digital Video Chroma Subsampling How to decimate for chrominance?
The 625/50 PAL Video Signal and TV Compatible Graphics Modes. A regular PAL tv set can be thought of as a low resolution fixed-frequency monitor. Usually, the PAL video characteristics are as follows: So, basically there are 625 scanlines per one video frame, divided up to two 312.5-line interlaced fields. Each scanline has a duration of 64 µs. A new 312.5 scanline field is drawn in every 1/50 second. Since drawing each scanline takes 64 µs (that is, 0.000064 seconds), drawing two fields (a full video frame) takes 2 × 312.5 × 64 µs, which equals to 0.04 seconds (=1/25 seconds). On the other hand, there are 625 × 25 scanlines per second, which equals to 15625 (the line frequency). Now we have derived and double-checked almost all important numbers in the above table, except for line-blanking interval and active scanlines.
The "active" part of the signal Active scanlines per field But wait, it is a bit more complicated than that: the analog tv standards dictate that only the second half of line 23 is used for active image, and, likewise, only the. Digital Video for the Web. Brief Description of Video and Image Formats. Digital Video D1 - is a component format.
The extremely high cost of D1 recorders limits their use to only the very elite production facilities that incorporate many special effects with multiple layering of the video signal. Such special effects layering does not degrade the image quality in the pure D1 digital environment. While most professional grade digital video is sampled at a rate of 4:2:2, or 4 samples of Y, 2 of (R-Y), 2 of (B-Y), D1 is 4:2:2:4. This 4:2:2:4 sampling permits an alpha (transparency, or linear keying) channel to be recorded. (Sampling Ratio 4:2:2:4; max. D2 - This is a composite format, but the quality is so high that signal degradation due to the mixing of video information is kept to a minimum. D3 - D3 is also a composite format like D2. D5 - This is a component format rather than composite.
Digital Betacam - This is the most commonly used video format in post production due to excellent picture reproduction and reasonable cost. RGB vs. Terms. Pal Secam NTSC World Standards Conversion Transfer Convert. Black Grey Yellow Green Blue (Change background color on Mouse-Over above) NTSC What is NTSC 4.43 PAL PAL-N PAL-M SECAM What is MESECAM World Standards Lookup Table 3.579545 Subcarrier Explained How a Video Standards Converter Works What are the PAL-B, G, H, I & D Variations all about ? There are several different and incompatible video formats in use around the world. Video broadcasts and recorded material in the US will not play on equipment in Europe for example - and vise versa ! The following also contains a brief history and description of world video standards, and articles on how a standards converter works.
Today's date is Monday, April 01, 2013. NTSC (National Television System Committee) (also lovingly referred to by engineers as "Never The Same C olor" owing to the system's inherent difficulty in maintaining color consistency) The NTSC standard was introduced in the US in 1941 as the first set of standard protocols for television. Variations: NTSC 4.43 Technical Specs: Variations: