 |
Video Testing made Easy for Broadcasters
Author: Bill Reckwerdt  | Posted: 12-12-2006 | Comments: 0 | Views: 151 | Rating: (50)  (?) 
This paper explores the challenges Broadcasters face when assessing video quality. Many factors affect the video before it gets to the TV: compression, image processing, scaling, decoding, transmission, etc.
Video processing and compression algorithms change the characteristics of the original program in the quest of reducing the bandwidth needed to send the programming information to the home. The art is to do this without allowing the audience to perceive a change in video quality. Successful video processing and compression algorithms perform the desired modifications while presenting a result to the viewer that, subjectively, looks natural and realistic. This sounds difficult, but it is necessary when transmitting many channels of high-quality programming.
Each broadcaster - traditional or web caster - must deal with rapidly changing varieties of programming, new video processing algorithms, and new compression algorithms. Video processing and compression companies continuously invent sophisticated ways to reduce the huge bandwidth requirements to manageable levels. How can broadcasters know if a new algorithm is better than their current choice?
Broadcasters invite the various video processing and compression companies into their R&D facilities, and perform side-by-side tests also known as a "bake-off". Each vendor starts with the same source material, and does their best to reduce the bandwidth while keeping the video quality high.
The broadcaster shows the results to a group of experts and asks them, which one is the best. This is termed subjective video analysis, and it measures the overall perceived video quality. The most commonly used video quality evaluation method is the Mean Opinion Score (MOS), recommended by the ITU. It consists in having several experts viewing a known distorted video sequences in order to rate its quality, according to a predefined quality scale. By doing this the expert viewers are trained to build a mapping between the quality scale and a set of processed video sequences. After the "training" is complete, the subjects are then asked to rate the new video processing algorithms.
Simply stated, the test setup is
* Start with a known video sequence.
* New Video Processing system alters the video sequence.
* Display the original and processed video sequences.
* Bring in experts to subjectively vote.
Complexity arises as
* New Video Processing systems may need new equipment to playback the video sequences.
* The original and processed video sequences should be displayed in random orders.
* Expert viewers are expensive and do not produce repeatable results.
Easier Solution
To streamline the process, equipment for video quality testing needs to be defined, which can capture, play, and analyze any two video sequences. Further, as new input/output modules are continuously under development, the test equipment should use an open-architecture approach to ease upgradeability.
Video Clarity defined the ClearView product line with these objectives in mind.
* Capture video sequences in as many formats as possible.
* Convert all video sequences to user-selectable resolution.
* Translate all video sequences to uncompressed Y'CbCr 4:2:2 or RGB 4:4:4.
* Support 8 and 10-bit data paths with upgradeability to future 12-bit modes.
* Store the video sequences as frames (fields) so that they can be played at any rate.
* Display the video sequences in real time in multiple viewing modes.
* Apply objective metrics to the video sequences.
* Export pieces of video sequences to further analyze off-line.
* Use a standard operating system so that the operator can run 3rd party analysis applications.
By working in the uncompressed domain, any two video processing algorithms can be compared independent of compression or other processing.
To further simplify the work flow, any video sequence can be played; while capturing another video sequence, thus, combining the video server and capture device into one unit. By doing this, the original source is already inside the test equipment so captured content alignment is easily obtained.
The original and processed video sequences can be displayed - side-by-side, mirrored, or seamless split - on a single display. This eliminates the need to calibrate two separate displays.
Further the operator can play any stored video sequence, at any speed, for any duration either manually or using automated play lists.
ClearView applies various objective metrics to the video sequences, generates graphs, and calculates an objective score.
While development of additional objective algorithms is ongoing, we have built a hybrid system that takes into consideration subjective testing with objective measurements. ClearView can easily be programmed to display video sequences for the expert viewers; while recording the objective metric scores along with the MOS. While the MOS cannot be repeated, the objective metric can, easily and readily.
Since the system is based on an open, Windows-based architecture, any objective measurement algorithm can be modeled off-line using the stored video sequences.
Benefits
* Repeatable tests, quantitative results, and a streamlined setup.
* Analyze 2 video sequences in real-time up to 1080P.
* Input virtually any file type or capture from any digital or analog source.
* Multiple viewing modes are presented on a single display - no need to calibrate 2 separate Television displays to compare video sequences.
* Integrated uncompressed, high definition Video Server and Capture Device.
* Ability to Play 2 fully uncompressed, HD Streams in Real-Time.
* Hybrid Solution with Integrated Objective Metrics and Subjective Viewing Modes.
Case Examples
A Broadcaster or Service Provider needs to
* Play out "Source" video sequences at various resolutions and rates to their encoder and/or video processing equipment.
* Capture the output of the encoder and/or video processing equipment.
* Capture the output from the STB.
* Test the quality of the encoder, video processing, and set-top box equipments. To do this, they need to
- Bring in Subjective Experts to choose the appropriate vendor ("bake-off") or to choose the correct settings.
- Generate a Score for repeatability.
A Solution/System Integrator creates a broadcast solution using encoder, network, video processing, VOD, conditional access, and set-top box providers. They market and sell their solution to Broadcasters or Service Providers. So they perform all of the above tests. When they cannot bring the Broadcaster or Service Provider into their viewing room to see the solution, they would like to take the test results to the Broadcaster. Thus, they have the additional requirement for a
* Portable solution to show side-by-side comparisons to the Broadcaster or Service Provider.
Summary
ClearView takes advantage of the high-reliability of today's off-the-shelf computer platforms. This ensures that products are made with state-of-the-art hardware, while at the same time avoiding the high cost of custom designs.
ClearView provides broadcasters, video researchers, compression developers with the unique ability to capture, play-out, and analyze video sequences. Objective measurements are generated and logged for repeatable tests.
Rate this Article:
Current: 0 / 5 stars - 0 vote(s).
Article Source: http://www.articlesbase.com/cable-and-satellite-tv-articles/video-testing-made-easy-for-broadcasters-81319.html
|
Submitting articles has become one of the most popular means of generating quality backlinks and targeted traffic to your website. Join us today - It's Free! |
|
Related Articles
Measuring to Find the Best Video Processing and Compression Algorithms
By: Bill Reckwerdt | 12/11/2006 | Cable and Satellite TV
Each broadcaster - traditional or web caster - must deal with rapidly changing varieties of programming, new video processing algorithms, and new compression algorithms. This whitepaper discusses how to choose the best algorithm.
Current Status of Video Objective Measurements
By: Bill Reckwerdt | 15/11/2006 | Cable and Satellite TV
This paper explores the challenges associated with assessing video quality. When dealing with equipment to process TV & video transmissions, every design depends on accurate, repeatable measurements. A complex relationship between objective parameter measurements and subjective video quality exists. The goal is to achieve an objective metric; that is an automated measurement.
1080p LCD and Plasma TV Technology
By: Scott Smith | 02/03/2007 | Technology
1080p LCD and Plasma TVs are the latest technology has available. If you're looking into new tv's and you're wondering what kind of technology might be the best choice, consider a 1080p TV. 1080p TVs give top picture quality, the best in HDTV standard. 1080p is also the digital standard for movies as well. When you go to the movie theatre to see the latest flick, you're actually viewing the movie on a 1080p digital movie projector.
Which Resolution Do I Need 720p, 1080p?
By: David Tanguay | 04/06/2007 | Technology
High definition is the best available picture for TV viewing; HD comes in 720p and 1080p. 720p and 1080p are both standards of high definition signals.
Which Television Should You Buy: Plasma Or LCD?
By: Mark St. Denis | 01/03/2008 | Electronics
Consumers face a tough decision when they are selecting a television to purchase. Many go to their local retailer to purchase a television and many purchase a television on the world wide web. This article discusses the advantages and disadvantages of lcd (liquid crystal display) and plasma flat screen or flat panel televisions.
The 52″ 1080p Sony Bravia Kdl-52w3000 LCD Hdtv is Simply an Amazing Set
By: Eric Ha | 09/03/2008 | Electronics
The 52″ 1080p Sony Bravia KDL-52W3000 LCD HDTV is simply an amazing set. This is one of the best 52” LCD HDTVs out there. This set is loved by many and you can check all over the internet and you’ll see that I’m not fibbing. Sony just keeps making the Bravia better and better with each new model release. If you’re looking for a 52” LCD HDTV and this one is in your budget, this may be the best one out there.
Information on LCD Tvs, Hdtvs, 720p, 1080i, and 1080p Resolutions
By: Prim Tin | 13/06/2008 | Electronics
The electronics industry has been growing at a rapid pace and various mode of entertainment has been introduced. LCD TV, Plasma, HDTV and TFT screens are few of those modes. This article discusses the different types of LCD HDTVs and the different features, advantages, and disadvantages of each.
Got a Question? Ask.
Ask the community a question about this article:
Q&A Powered by: 
Latest Cable and Satellite TV Articles
More Cable Customers are Switching to Directtv Satellite TV Everyday
By: Martha J Coleman | 05/09/2008
One of the best ways to judge the quality of any product or service is by the people that are using it. In customer satisfaction, DirecTV consistently outperforms all cable companies. The number of customers they have is more than 16 million, and they are the number one Satellite Television provider in the nation. It's easy to understand why so many people are switching based on the numbers.
Directv Satellite TV is Taking More Cable Customers Away Everyday
By: Martha J Coleman | 05/09/2008
One of the best ways to judge the quality of any product or service is by the people that are using it. Direct TV's customer satisfaction has consistenly been ranked higher than Cable's. They have over 16 million customers and are the #1 Satellite Television provider in the country. It's easy to understand why so many people are switching based on the numbers.
A Veritable First Hand Critical Review of Satellite TV Software
By: Charles | 05/09/2008
It was but a few months ago that I first heard of the new phenomenon described as Internet television software or Satellite TV for PC software. Of course I did not believe the story, but it kept making the rounds.
Satellite TV From Directv is Signing Up More Cable Customers Everyday
By: Martha J Coleman | 04/09/2008
One of the best ways to judge the quality of any product or service is by the people that are using it. Direct TV's customer satisfaction has consistenly been ranked higher than Cable's. DirecTV has taken the lead in their category with more than 16 million active customers. With those numbers it is easy to understand why so many are switching over to them.
Millions of Directv Customers are Completely Satisfied
By: Martha J Coleman | 04/09/2008
current customers of the service or product is the most effective way to gather information on the quality of it. DirecTV is ranked ahead consistently among every cable provider in regard to customer satisfaction. They have over 16 million customers and are the #1 Satellite Television provider in the country. It is quite apparent that with those exact numbers it is clear that numerous individuals are making a change
Cable Business is Disappearing as Customers Switch to Directv Satellite
By: Martha J Coleman | 03/09/2008
Current customers of the service or product is the most effective way to gather information on the quality of it. Cable providers can't compete with Direct Tv in Customer Satisfaction. They are the country's number one Satellite Television provider, with over 16 million customers. It is quite apparent that with those exact numbers it is clear that numerous individuals are making a change.
Incredible Deals - Direct TV Specials
By: Gordon Runquest | 03/09/2008
If you have a passion for sports, you may want to learn how watching games could save you money. Direct TV has a special available right now which allows you to get four free months of Direct TV programming with your purchase of NFL Sunday Ticket.
Dont Buy Any Satellite TV for Pc
By: jaime reina | 02/09/2008
Before of buy Satellite Tv For PC is very important discover the best features and the best system
More from Bill Reckwerdt
How to Do Objective Video Testing
By: Bill Reckwerdt | 23/04/2007 | Cable and Satellite TV
To make optimal choices, it is necessary to have knowledge about how particular choices affect the impression of the viewer. This is the central question of all video quality research.
Video Testing for STB Manufacturers
By: Bill Reckwerdt | 05/04/2007 | Cable and Satellite TV
Set-top box (STB) functions are continually advancing, but the customers' reactions are usually centered on the quality of the picture. So testing is increasing important.
Video Testing for Broadcasters
By: Bill Reckwerdt | 05/04/2007 | Cable and Satellite TV
Each broadcaster - traditional or web caster - must deal with rapidly changing varieties of programming, new video processing algorithms, and new compression algorithms. How can broadcasters know if a new algorithm is better than their current choice?
Video Testing for Encoder Manufacturers
By: Bill Reckwerdt | 05/04/2007 | Cable and Satellite TV
For visual and audio data, some loss of quality can be tolerated without losing the essential nature of the data. By taking advantage of the limitations of the human sensory system, a great deal of space can be saved while producing an output which is nearly indistinguishable from the original.The question must be asked. How much data can be removed before the customer has a violent reaction.
Who Are You Going to Believe, Me or Your Own Eyes?
By: Bill Reckwerdt | 20/03/2007 | Advertising
Over recent years, advances underlying the capture, transfer, storage, and display of images have created situations where video communication has become economically feasible. This paper creates a framework for optimal compression/ CODEC trade-off choices.
Repeatable Video Testing Tools for Equipment Manufacturers
By: Bill Reckwerdt | 12/12/2006 | Cable and Satellite TV
This paper explores the challenges Video Equipment Manufacturers face when assessing video quality. Assessing video quality ultimately depends on the customer's reaction on their new display (PC, POD, TV, etc.).
Current Status of Video Objective Measurements
By: Bill Reckwerdt | 15/11/2006 | Cable and Satellite TV
This paper explores the challenges associated with assessing video quality. When dealing with equipment to process TV & video transmissions, every design depends on accurate, repeatable measurements. A complex relationship between objective parameter measurements and subjective video quality exists. The goal is to achieve an objective metric; that is an automated measurement.
Measuring to Find the Best Video Processing and Compression Algorithms
By: Bill Reckwerdt | 12/11/2006 | Cable and Satellite TV
Each broadcaster - traditional or web caster - must deal with rapidly changing varieties of programming, new video processing algorithms, and new compression algorithms. This whitepaper discusses how to choose the best algorithm.
|
|
Technology 
