What Is MPEG 1 ?
MPEG stands for Moving Picture Expert Group. It is working group of ISO(International organization Of Standardization). MPEG is Digital Video Compression standard.
The First standard launched by MPEG was MPEG 1. MPEG 1 provides the video resolution of 352 by 240 at 30 fps. It provides the lower quality than VCR. MPEG 1 is used for transmission of non-interlaced videos.
What Is Interlaced Video ?
Pictures in TV contains many closely spaced lines.These lines are scanned and pictures are produced.For NTSC these lines are 525 while for PAL format these lines are 625.
Initially these lines were writing on the screen in sequence like 1,2,3,4..etc. Thus in the last lines of scanning the pictures start fading from upper side. So this sequential order of scanning did get success.
To avoid this problem we decided to scan first odd number of lines like 1,3,5…etc. than even lines 2,4,8…etc. so after tracing the total odd lines then it start tracing even lines which did not results fading in pictures. Thus fading of picture was reduced.
Usually when we start playing videos on monitor then we reduced fading in monitors by making progressive scan. This progressive scan is called non interlaced video. Thus MPEG 1 is used for non interlaced videos. This progressive scan is done in monitors.
What Is MPEG 2 ?
MPEG 2 provides the resolution of 720*480 and 1280*720 at 60 fps (frame per second).It is used by DVDs.
MPEG 2 uses the Inter frame compression as well as intra frame compression.
Inter frame compression means it compares the current frame with last sent frame. Only different frames are sent and repeating frames are not sent. Thus it avoid the repetition of frames. So it is called the inter frame compression. By reducing the number of frames it consumes less bandwidth.
While in intra frame compression each selected frame is divided into the blocks of 8*8 pixels. These pixels are compared with the nearest pixels. Only different pixels are sent.
MPEG 2 compression reduces 90 mbps bandwidth video into the less than 1.5 mps video. This huge saving of bandwidth without loss in the quality of the picture.
What Is MPEG 3 ?
It was designed for High Definition Television. But it was abounded and incorporated into the MPEG 2.
What Is MPEG 4 ?
MPEG 4 is higher quality compression technique than the previous one. Also it avoids the limitation of MPEG 2.It was standardized in October 1998. It is applicable for
Web pages
Digital TV
Animated Graphics
MPEG 4 compression utilities the Media Blocks concepts. These Media Blocks are also called Media Objects.
Media Blocks contains basically three parts
(1) Video Object
Video object is the moving object in the video. A football player is video object which is moving continuously in football match.
(2) Audio Object
There are two type of voice in the football match. one voice is from the commentator and other one voice is from background.
(3) Still Images
The background in the match is the still images. The public watching the match is the in the still images section.
By joining above mentioned three parts makes the Media Blocks. Multiple Media Blocks are called the Compound Media Blocks.
These compound media blocks are synchronized and multiplexed to make the picture.
What Is MPEG 7 ?
As we all knows day by day hard disc space is increasing. Thus in this case we need a setup for retrieval of saved data quickly. This data is multimedia content. This multimedia content can be images,videos,music files and drawing. Thus queries are done to reach the desired content.
It is called the Multimedia Content Description Interface. MPEG 7 describe the multimedia content.
Drawing can be search by drawing the relevant lines on the screen.
We need to define the texture to reach the desired textures
By playing few parts of song we can reach at the desired song.
What Is MPEG 21 ?
MPEG 21 standard is used to search the content,describe the content,storing the content, protect the data from copyrights.It uses REL and RDD. Where REL stands for Right Expression Language and RDD for Rights Data Dictionary.
It provides the multimedia framework. Which is used to sharing the content legally on network and devices.It plays a important role for intellectual property by managing and protecting it.
Conclusion Of MPEG
MPEG provides the different compression algorithm which uses to compress the data to save the bandwidth. MPEG 2 system reduces the 98 % of data. Thus this 98% useless information is discarded to save the bandwidth by maintaining the good quality of content. While MPEG 4 system discard the 70% information of MPEG 2.
MPEG 3 was developed for HDTV but later abounded. MPEG 7 provides the easy retrieval of stored content or data. MPEG 21 is used for protection and management of Intellectual Property.
Thus this is all about difference between MPEG 1 and MPEG 2, MPEG 3, MPEG 4, MPEG 7 & MPEG 21 .
reference : mpeg
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Thank you so much for this article. It will be of great help for students who want to know the difference between MPEG versions.
Have not got article like this before where so simply and clearly described on MPEG versions.
Your Welcome. We have also published Headend INFO Books to clear these concepts you can visit here Headend INFO Books
This is really nice article… thank you so much
your welcome !!! you can find more details in Headend INFO Books