Progressive Download versus Streaming
In the last couple of weeks several clients have been asking about the difference between steaming and progressive download delivery methods.
Let’s start with progressive downloads. The video is actually downloaded to the viewer’s computer, and stored in a temporary directory. Content will start playing out as soon as it is available locally. If the viewer wants to fast forward or skip to another section, he/she will only be able to do so if that part of the video has already been delivered and stored on their machine. The video is delivered via the standard http protocol like any other webpage.
Streaming video on the other hand is delivered via a streaming server without the file ever being downloaded to the viewer’s computer. As soon as the viewer presses play, the video will start to play. If the user decided to forward or skip to some other part of the video, he/she can do it immediately and the video will continue to play from that point onwards. One of the big positives of streaming media is that only the bandwidth is used that the viewer indeed has watched, as only the portion of video that has been watched had been delivered. Nothing is kept on the client side; everything is on the server side and is being delivered via the Real Time Messaging Protocol (RTMP), which is a proprietary protocol, developed by Adobe.
In practice you will very rarely realize weather the content has been streamed or progressively downloaded, unless you look for some of the distinguished features as described above.
Progressive Download: Video is downloaded onto the user’s computer
- Advancing is not possible unless it has been downloaded already
- Does not effectively utilize Brightcove’s dynamic delivery feature
- Less secure, content can be easily copied
- More bandwidth is used as all parts of the video are downloaded, not just the watched once
- http protocol in use
- Secures video content via temporary video link
- Advancing video is possible
- Effectively utilizes Brightcove’s dynamic delivery feature
- Allows you to serve more steams with less bandwidth
- Real Time Messaging Protocol (RTMP) in use
Brightcove supports both types of delivery methods, which is set on account level. If switching from one type of delivery to the other, you will find that the videos already uploaded to Brightcove will remain in the original format.
You would think that streaming would be the obvious choice as it has certain advantages over progressive download, having said that we have many customers who use progressive download. For example, one of my clients in Germany switched to progressive download because of the firewall restrictions on German cooperate networks.
Another reason for using progressive download, would be the use of the Brightcove sample to build an i-phone application, http://developer.brightcove.com/en/articles/iphone-video-portal-sample-application, which works with progressive download.