In describing the technologies and applications dedicated to video viewing, a very specific terminology is used that is unknown to most people.
Following this document, we briefly describe the most important terms, as follows:
By encoder we mean a program encoding and decoding a specific analog form, for example a video (an example of a encoder is Sorenson Spark),
The term form means the set of rules and conventions used to encode digital information, such as video (an example of a form is Mpeg-4)
By playback program, we mean the specific application used to access a service, such as watching a video (an example of a playback program is Flashplayer).
The term plugin refers to an autonomous program that interacts with another program, the main program, to extend the functions of the main program itself.
A historical analysis
YouTube is a web platform that allows you to watch and share videos online. Youtube is constantly evolving and with a continuous series of changes within the platform.
In this article we will explain the various video formats and their features, encoders, playback programs and add-ons that have been used since 2005, the date YouTube was founded, until today.
Since 2009, the reference technologies used by the site are HTML5 for Wed and Mpeg-4 pages with H264 encoder for video. Previously, the site used Macromedia Flashplayer 7 with video encoder Sorenson Spark H.264. The features of this player are similar to many other players such as Windows Media Player, RealPlayer or Apple QuickTime Player. On the other hand, this player had a downside as it required the installation of an add-on, which could be Adobe Flash Player or Gnash. To date, Youtube accepts videos in WMV, AVI, QTTF, ogg and MPEG formats (3gp, MPEG-1, MP4e M4v)
Since March 2008, YouTube has been able to see some “high quality” (HQ) videos. After the last interface changes, this functionality is activated by clicking the “View” button located below the video viewing window. This functionality can also be activated for high quality videos by adding the “& fmt = 18” string to the end of the video address.
In November 2008, the ability to view high definition video (720p) was added, ie better quality video than the high quality mentioned above (HQ). If there is a function, just click the HD button on the playback line or add the “& fmt = 22” string at the end of the video address.
In November 2009, HD functionality was upgraded from 1280 × 720 (known as 720p) to 1920 × 1080 full HD (known as 1080p), compatible with HD cameras and monitors. In any case, a video that is loaded with high definition is always possible to play even in the lowest definition.
Support for 4K video resolution (4096 × 3072 pixels) was also implemented in July 2010.
The available definitions are as follows:
144p (176 × 144): low quality for portable devices.
240p (320 × 240) – High quality for portable devices.
360p (480 × 360/640 × 360);
480p (640 × 480/854 × 480) – equivalent to that of a DVD video.
720p (1280 × 720);
1080p (1920 × 1080): equivalent to that of a Blu-ray disc.
1440p (2560 × 1440);
2160p (3840 × 2160);
4K (4096 × 3072): used in digital cinema.
8K (7680 × 4320) – “extremely high definition”, experimentally digital video format.
Since July 2009, YouTube has been able to upload stereoscopic (3D) videos and display them through its playback program in a variety of ways, both with embossed (old two-color lenses) and with a 3D screen with IR transmitter and active glasses . .
Sorenson Codecs
Figure 1.2 Sonseron
This encoder (also known as Sorenson Video Codec, Sorenson Video Quantizer or SVQ) is a proprietary digital video encoder, invented by Sorenson Media Inc. This encoder is used in Apple’s QuickTime Player and Adobe Flash.
There are three different Sorenson encoders:
Sorenson Video: Two editions of Sorenson Video have been released. The first version first appeared on QuickTime 3 on March 30, 1998. The second compatible version was released with QuickTime 4 in 1999, which included minor improvements and optimizations to the Edition Edition, and then coded the videos.
