Introduction
There are various HTTP streaming protocols available like HDS, HLS and MPEG DASH etc. Each one is having its different mechanism for streaming media online. These all three works with live video as well as pre-recorded videos like Video On Demand.
Today in this article we will cover What is HDS , its working and how it is better than HTTP Progressive Download.
What Is HDS
HDS stands for HTTP Dynamic Streaming. HDS is Adaptive Bitrate streaming protocol for delivery of live and pre recorded MP4 videos for Flash Player online. HTTP Web servers are used for streaming. Its adaptive bit rate facilitate to user end device to use lower data rate media or higher data rate media for playing in real time.
HTTP Dynamic Streaming was developed by Adobe for playing videos in Adobe flash player or Adobe Air. So can be streamed on any device which support Adobe Flash Player. It provides the facility of encryption and authentication for content.
Working Of HDS
As we can see above in the figure we need to provide media input if we want to stream live media otherwise media is pre recorded like VOD then can directly take from server. Now after finding media it is converted into MPEG 4 ts and created basically three files named as segment file , manifest file and index file.
these three files plays an important role in HDS Streaming.
(1) Segment File = .f4f
(2) Manifest File = .f4m
(3) Index File = .f4x
(1) Segment File .f4f
.f4f is the extension of segment files. For one media file there will be multiple segment file according to its data rate. Each segment file contains many fragments. URLs are used to locate these fragments.
For example if my media file name is “headendinfo” then there will be delivered segment files as mentioned below,
(A) headendinfoSeg1.f4f
(B) headendinfo_300kSeg1.f4f
(C) headendinfo_600jkSeg1.f4f
(D) headendinfo_1200kSeg1.f4f
(2) Manifest File .f4m
.f4m is the extension of the Flash Media Maifest File. Manifest File contains the data rate information and its resolution with its codec information of Media File. It can be described as in case of “headendinfo” file name,
(A) headendinfo_300k.f4m
(B) headendinfo_600k.f4m
(C) headendinfo_1200k.f4m
(3) Index File .f4x
.f4x is the extension of Index File. This Index File contains the specific fragment’s location. It can be described as in case of “headendinfo” file name,
(A) headendinfoSeg1.f4x
(B) headendinfo_300kSeg1.f4x
(C) headendinfo_600jkSeg1.f4x
(D) headendinfo_1200kSeg1.f4x
Now these files contains small chunks and its url as we have discussed above. Then these files goes through distribution system (as per requirement of user end device) mentioned in diagram as CDN (Content Delivery System). At the user end if the user is having adobe license then it approve for media streaming.
Advantages Of HTTP Dynamic Streaming
Previously we were using the HTTP Progressive Download which was not that much efficient for delivery of media content online. Because in HTTP Progressive Download if user seek the courser in the middle of video while playing then video could not start from selected point. The whole video needs to download then you can play and seek.
On the other hand it is not in the HTTP Dynamic Streaming. The user can seek the video while playing and can watch it from there contentiously. HTTP Dynamic Streaming is having low delivery cost due to catching of server.
Conclusion
HDS is adaptive streaming protocol to deliver media online for adobe flash players. It is having efficient streaming of media than its predecessor HTTP Progressive Downlod. it is roubust technology as well as flexible too. It provide complete protection so that service provider can information of subscription also he can track data consumption of particular subscriber too.
Know More About What Is HLS HTTP Live Streaming
