Progressive download
Encyclopedia
Progressive download is a term used to describe the transfer of digital media
files from a server
to a client, typically using the HTTP protocol when initiated from a computer. The consumer may begin playback of the media before the download is complete. The key difference between streaming media
and progressive download is in how the digital media data is received and stored by the end user device that is accessing the digital media.
A media player that is capable of progressive download playback relies on meta data located in the header of the file to be intact and a local buffer of the digital media file as it is downloaded from a web server. At the point in which a specified amount of data becomes available to the local playback device, the media will begin to play. This specified amount of buffer is embedded into the file by the producer of the content in the encoder
settings and is reinforced by additional buffer settings imposed by the media player.
was the first visual media to render a progressive visual display as the digital media was downloaded and actually referred to as a progressive download. The distinction between the technical behavior of progressive download as opposed to the common or commercial use of the term progressive download to describe that behavior was not documented and there is a good deal of question regarding the origin of the term versus the origin of the technical implementation. Apple
in reference to their Quicktime
media player employed the term Fast Start in 1997, to describe what was commercially referred to as progressive download playback of encoded digital media
content.
This fast start playback is the result of moving the meta data from the end of the digital media file to the front, this move of the meta data gave the media player all the information it required to begin playback as the file was still being downloaded. Prior to that change, the meta data summary was located at the end of a digital media file and the entire file would need to be downloaded in order for the meta data to be read and the player begin play back.
, however the digital file is downloaded to a physical drive on the end user's device, the digital file is typically stored in the temp folder of the associated web browser if the digital media was embedded into a web page or is diverted to a storage directory that is set in the preferences of the media player used for playback. The digital media file will stutter or stop play back if the rate of play back exceeds the rate at which the file is downloaded. The file will begin to play again after further download.
HTTP Progressive download opens digital media to piracy in that it can be saved and shared by the end user. Due to this unrestricted access to the digital media file, entities concerned with piracy and security of their data opt for streaming based solutions that create a small buffer in order to initiate playback; however at no time during a streaming media
session is the entire file downloaded locally as it is in the Progressive download scenario.
Digital media
Digital media is a form of electronic media where data is stored in digital form. It can refer to the technical aspect of storage and transmission Digital media is a form of electronic media where data is stored in digital (as opposed to analog) form. It can refer to the technical aspect of...
files from a server
Web server
Web server can refer to either the hardware or the software that helps to deliver content that can be accessed through the Internet....
to a client, typically using the HTTP protocol when initiated from a computer. The consumer may begin playback of the media before the download is complete. The key difference between streaming media
Streaming media
Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a streaming provider.The term "presented" is used in this article in a general sense that includes audio or video playback. The name refers to the delivery method of the medium rather...
and progressive download is in how the digital media data is received and stored by the end user device that is accessing the digital media.
A media player that is capable of progressive download playback relies on meta data located in the header of the file to be intact and a local buffer of the digital media file as it is downloaded from a web server. At the point in which a specified amount of data becomes available to the local playback device, the media will begin to play. This specified amount of buffer is embedded into the file by the producer of the content in the encoder
Encoder
An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format or code to another, for the purposes of standardization, speed, secrecy, security, or saving space by shrinking size.-Media:...
settings and is reinforced by additional buffer settings imposed by the media player.
History
Initially the digital media file type known as jpegJPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....
was the first visual media to render a progressive visual display as the digital media was downloaded and actually referred to as a progressive download. The distinction between the technical behavior of progressive download as opposed to the common or commercial use of the term progressive download to describe that behavior was not documented and there is a good deal of question regarding the origin of the term versus the origin of the technical implementation. Apple
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
in reference to their Quicktime
QuickTime
QuickTime is an extensible proprietary multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. The classic version of QuickTime is available for Windows XP and later, as well as Mac OS X Leopard and...
media player employed the term Fast Start in 1997, to describe what was commercially referred to as progressive download playback of encoded digital media
Digital media
Digital media is a form of electronic media where data is stored in digital form. It can refer to the technical aspect of storage and transmission Digital media is a form of electronic media where data is stored in digital (as opposed to analog) form. It can refer to the technical aspect of...
content.
This fast start playback is the result of moving the meta data from the end of the digital media file to the front, this move of the meta data gave the media player all the information it required to begin playback as the file was still being downloaded. Prior to that change, the meta data summary was located at the end of a digital media file and the entire file would need to be downloaded in order for the meta data to be read and the player begin play back.
HTTP Progressive Download versus Streaming Media
The end user experience is similar to streaming mediaStreaming media
Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a streaming provider.The term "presented" is used in this article in a general sense that includes audio or video playback. The name refers to the delivery method of the medium rather...
, however the digital file is downloaded to a physical drive on the end user's device, the digital file is typically stored in the temp folder of the associated web browser if the digital media was embedded into a web page or is diverted to a storage directory that is set in the preferences of the media player used for playback. The digital media file will stutter or stop play back if the rate of play back exceeds the rate at which the file is downloaded. The file will begin to play again after further download.
HTTP Progressive download opens digital media to piracy in that it can be saved and shared by the end user. Due to this unrestricted access to the digital media file, entities concerned with piracy and security of their data opt for streaming based solutions that create a small buffer in order to initiate playback; however at no time during a streaming media
Streaming media
Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a streaming provider.The term "presented" is used in this article in a general sense that includes audio or video playback. The name refers to the delivery method of the medium rather...
session is the entire file downloaded locally as it is in the Progressive download scenario.