วิดีโอคลิป หรือ คลิปวิดีโอ (บางครั้งเรียกสั้นๆ ว่า คลิป ก็มี) ก็คือ ไฟล์คอมพิวเตอร์ที่บรรจุเนื้อหาเป็นภาพยนตร์สั้น มักจะตัดตอนมาจากภาพยนตร์ทั้งเรื่องซึ่งมีขนาดความยาวปกติ คลิปมักจะเป็นส่วนที่สำคัญ หรือต้องการนำมาแสดง มีความขบขัน หรืออาจเป็นเรื่องความลับที่ต้องการนำมาเผยแพร่ จากต้นฉบับเดิม แหล่งของวิดีโอคลิป ได้แก่ ข่าว ข่าวกีฬา มิวสิกวิดีโอ รายการโทรทัศน์ หรือภาพยนตร์ ปัจจุบันมีการใช้วิดีโอคลิปแพร่หลาย เนื่องจากไฟล์คลิปนี้มีขนาดเล็ก สามารถส่งผ่านอีเมล หรือดาวน์โหลดจากเว็บไซต์ได้สะดวก ในประเทศตะวันตก เรียกการแพร่หลายของวิดีโอคลิปนี้ว่า วัฒนธรรมคลิป (Clip Culture)
คำคำนี้ มีความหมายกว้างๆ หมายถึง ภาพยนตร์สั้นแบบไหนก็ได้ ที่มีความยาวน้อยกว่ารายการโทรทัศน์ตามปกติ (โดยมากไม่เกิน 5-10 นาที และที่พบบ่อยที่สุดคือประมาณ 1 นาที)
จากการใช้งานอินเทอร์เน็ตความเร็วสูง ยิ่งทำให้วิดีโอคลิปเป็นที่นิยมและแพร่หลายมากขึ้นไปอีก ในต้นปี พ.ศ. 2549 ประมาณว่า มีวิดีโอคลิปให้โหลดออนไลน์นับล้านไฟล์ เว็บไซต์ยอดนิยมได้แก่ www.ifilm.com www.youtube.com video.google.com
จากวิกิพีเดีย สารานุกรมเสรี
video clip
Thursday, March 27, 2008
Wednesday, March 19, 2008
Video clip
Video clips are short clips of video, usually part of a longer piece.
Video clips in digital format are often found on the internet where the massive influx of new video clips during 2006 was hailed as a new phenomenon having a profound impact on both the internet and other forms of media. Sources for video clips include news and sporting events, historical videos, music videos, television programmes, film trailers and vlogs. Webvideo in its current form distinguishes itself from what is mostly known as video on demand mainly in terms of technology, interface and cost for the user. The current hype in online video viewing only arose when sites were introduced that offered free hosting for the high bandwidth content and the possibility to easily integrate these into personal Blogs or websites. This enabled online videos to cross over into the mainstream. The arrival of these sites also gave rise to more widespread use of the name webvideo. Video on demand however, is more closely associated with paid content of film studios, online video stores and cable providers. Video on demand also specifically references videos that start at a moment of the user's choice, as opposed to streaming, multicast and webcams in which the data is sent to the user live by a server.
The term is also more loosely used to mean any short video less than the length of a traditional television programme.
Reference : http://en.wikipedia.org/wiki/Video_clip
Video clips in digital format are often found on the internet where the massive influx of new video clips during 2006 was hailed as a new phenomenon having a profound impact on both the internet and other forms of media. Sources for video clips include news and sporting events, historical videos, music videos, television programmes, film trailers and vlogs. Webvideo in its current form distinguishes itself from what is mostly known as video on demand mainly in terms of technology, interface and cost for the user. The current hype in online video viewing only arose when sites were introduced that offered free hosting for the high bandwidth content and the possibility to easily integrate these into personal Blogs or websites. This enabled online videos to cross over into the mainstream. The arrival of these sites also gave rise to more widespread use of the name webvideo. Video on demand however, is more closely associated with paid content of film studios, online video stores and cable providers. Video on demand also specifically references videos that start at a moment of the user's choice, as opposed to streaming, multicast and webcams in which the data is sent to the user live by a server.
The term is also more loosely used to mean any short video less than the length of a traditional television programme.
Reference : http://en.wikipedia.org/wiki/Video_clip
Stereoscopic
Stereoscopic video requires either two channels — a right channel for the right eye and a left channel for the left eye or two overlayed color coded layers. This left and right layer technique is occasionally used for network broadcast, or recent "anaglyph" releases of 3D movies on DVD. Simple Red/Cyan plastic glasses provide the means to view the images discretely to form a stereoscopic view of the content.* New HD DVD and Blu-ray Discs will greatly improve the 3D effect, in color coded stereo programs. The first commercially available HD players were expected to debut at the 2006 NAB Show in Las Vegas in April. See articles Stereoscopy and 3-D- Max film.
Reference : http://en.wikipedia.org/wiki/Video
Reference : http://en.wikipedia.org/wiki/Video
Bit rate (digital only)
Bit rate is a measure of the rate of information content in a video stream. It is quantified using the bit per second (bit/s or bps) unit or Megabits per second (Mbit/s). A higher bit rate allows better video quality. For example VideoCD, with a bit rate of about 1 Mbit/s, is lower quality than DVD, with a bit rate of about 5 Mbit/s. HDTV has a still higher quality, with a bit rate of about 20 Mbit/s.
Variable bit rate (VBR) is a strategy to maximize the visual video quality and minimize the bit rate. On fast motion scenes, a variable bit rate uses more bits than it does on slow motion scenes of similar duration yet achieves a consistent visual quality. For real-time and non-buffered video streaming when the available bandwidth is fixed, e.g. in videoconferencing delivered on channels of fixed bandwidth, a constant bit rate (CBR) must be used.
Reference : http://en.wikipedia.org/wiki/Video
Variable bit rate (VBR) is a strategy to maximize the visual video quality and minimize the bit rate. On fast motion scenes, a variable bit rate uses more bits than it does on slow motion scenes of similar duration yet achieves a consistent visual quality. For real-time and non-buffered video streaming when the available bandwidth is fixed, e.g. in videoconferencing delivered on channels of fixed bandwidth, a constant bit rate (CBR) must be used.
Reference : http://en.wikipedia.org/wiki/Video
Video compression method (digital only)
A wide variety of methods are used to compress video streams. Video data contains spatial and temporal redundancy, making uncompressed video streams extremely inefficient. Broadly speaking, spatial redundancy is reduced by registering differences between parts of a single frame; this task is known as intraframe compression and is closely related to image compression. Likewise, temporal redundancy can be reduced by registering differences between frames; this task is known as interframe compression, including motion compensation and other techniques. The most common modern standards are MPEG-2, used for DVD and satellite television, and MPEG-4, used for home video.
Reference : http://en.wikipedia.org/wiki/Video
Reference : http://en.wikipedia.org/wiki/Video
Color space and bits per pixel
Example of U-V color plane, Y value=0.5
Color model name describes the video color representation. YIQ was used in NTSC television. It corresponds closely to the YUV scheme used in NTSC and PAL television and the YDbDr scheme used by SECAM television.
The number of distinct colours that can be represented by a pixel depends on the number of bits per pixel (bpp). A common way to reduce the number of bits per pixel in digital video is by chroma subsampling (e.g. 4:4:4, 4:2:2, 4:2:0).
Reference : http://en.wikipedia.org/wiki/Video
Color model name describes the video color representation. YIQ was used in NTSC television. It corresponds closely to the YUV scheme used in NTSC and PAL television and the YDbDr scheme used by SECAM television.
The number of distinct colours that can be represented by a pixel depends on the number of bits per pixel (bpp). A common way to reduce the number of bits per pixel in digital video is by chroma subsampling (e.g. 4:4:4, 4:2:2, 4:2:0).
Reference : http://en.wikipedia.org/wiki/Video
Aspect ratio
Comparison of common cinematography and traditional television (green) aspect ratios.
Aspect ratio describes the dimensions of video screens and video picture elements. The screen aspect ratio of a traditional television screen is 4:3, or about 1.33:1. High definition televisions use an aspect ratio of 16:9, or about 1.78:1. The aspect ratio of a full 35 mm film frame with soundtrack (also known as "Academy standard") is around 2.37:1.
Pixels on computer monitors are usually square, but pixels used in digital video often have non-square aspect ratios, such as those used in the PAL and NTSC variants of the CCIR 601 digital video standard, and the corresponding anamorphic widescreen formats. Therefore, an NTSC DV image which is 720 pixels by 480 pixels is displayed with the aspect ratio of 4:3 (which is the traditional television standard) if the pixels are thin and displayed with the aspect ratio of 16:9 (which is the anamorphic widescreen format) if the pixels are fat.
Reference : http://en.wikipedia.org/wiki/Video
Aspect ratio describes the dimensions of video screens and video picture elements. The screen aspect ratio of a traditional television screen is 4:3, or about 1.33:1. High definition televisions use an aspect ratio of 16:9, or about 1.78:1. The aspect ratio of a full 35 mm film frame with soundtrack (also known as "Academy standard") is around 2.37:1.
Pixels on computer monitors are usually square, but pixels used in digital video often have non-square aspect ratios, such as those used in the PAL and NTSC variants of the CCIR 601 digital video standard, and the corresponding anamorphic widescreen formats. Therefore, an NTSC DV image which is 720 pixels by 480 pixels is displayed with the aspect ratio of 4:3 (which is the traditional television standard) if the pixels are thin and displayed with the aspect ratio of 16:9 (which is the anamorphic widescreen format) if the pixels are fat.
Reference : http://en.wikipedia.org/wiki/Video
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