progressive download


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progressive download

A method for streaming non-live video to the user for immediate playback. Supported in the user's media player, progressive download employs HTTP, the protocol used to download everything from the Web. Unlike a regular download, progressive download lets users view the video as soon as a small amount of content has been received. The video is stored in a temporary folder and can be played again within the same user session but cannot be saved unless the media player offers that option. See HTTP.

A huge number of websites favor progressive downloads, including YouTube. These sites use free, open source Web server software, rather than proprietary streaming servers, such as Windows Media Services and Flash Media Server.

As long as the video describes its content structure in the front of the file (see metadata), modern content delivery networks (CDNs) enable fast forwarding into the middle of the video without downloading the preceding content.

Progressive Download vs. Real-Time Streaming
Although most users cannot tell the difference, progressive download stores the entire file, while "real-time streaming," sometimes called "true streaming," is analogous to broadcast radio and TV. Although there are always more video frames in the memory buffer at each moment, real-time streaming content essentially passes through the computer.

In addition, real-time streaming uses the UDP protocol, which may ignore lost packets and accept packets with errors. Progressive download uses TCP to ensure that each network packet arrives intact and will request retransmission if not. This can temporarily stop the video when only a momentary blip in viewing might have been observed. See streaming video and TCP/IP.


Filling the Buffer
The message means 70% of a reserved area in memory is filled. When it reaches 100%, the software (Windows Media Player in this example) will start "playing" the video.
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References in periodicals archive ?
Almost all of the newly developed adaptive bitrate streaming and progressive download technologies are now based on HTTP.
"The whole infrastructure behind the progressive download is completely separate from the broadcast element and, therefore, requires a completely new headend," explains Patel.
So other than behemoths such as YouTube, Netflix, and Hulu that use DASH, most other sites are either use HLS or progressive download. Luther predicted that by 2016, all major off-the-shelf players, including JW Player, will implement HLS playback in JavaScript using the Media Source Extensions.
Once the video is uploaded, it's automatically processed into a set of Smooth Streaming files for computer delivery and HLS for iOS, with a single file delivered via progressive download to Android devices.
Do you need a streaming player, or is progressive download a better option?
Even with these developments, there was still a problem: Most browsers would only play back content via progressive download. A video tag could only use a single, whole, web-hosted video file for its source.
The company offers solutions to bring your valuable content to the largest selection of platforms and consumer devices via progressive download, on-demand, and live streaming.
When CDNs first came into existence, the internet was mostly static content, with media files being delivered via progressive download. Content was being consumed at an exponentially growing pace by users around the world, and CDNs sprung up as an answer to the need for global delivery and load distribution for high volumes of traffic.
Every player discussed in this article can play VOD content served as a progressive download over HTTP (content playback can begin when a small buffer has downloaded, without requiring the entire video file to download) or as a byte range request.
We are no longer required to build separate mechanisms to handle all the permutations of HTTP and non-HTTP streaming technologies, as well as progressive download, pseudo-streaming, and many other formats.
I think back to when I first joined Streaming Media in 2004 and got into a heated argument about whether or not the term "streaming media" could be used generically to refer to either streaming or progressive download, or whether we must be slaves to a distinction that, to most consumers, doesn't exist.

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