VideoSQL is a query language of OVID for retrieving video-objects. Here is an example.

Figure 11. VideoSQL.

• Users can formulate VideoSQL queries in a fill-in-the-blank manner
• The result of a VideoSQL query is a collection of video-objects that satisfy the specified condition.
• A VideoSQL query consists of the following clauses
  • SELECT clause: It is quite different from ordinary SQL. It specifies only the category of the resulting video-objects.
    • Continuous: only the video-objects consisting of a single sontinuous video frame sequences are retrieved.
    • Incontinuous: only these consisting of more than one continuous video frame sequence are retrieved.
    • anyObject: the system retrieves all types of video objects, whether they are continuous or not.
  • FROM clause: specify the name of the video database.
  • WHERE clause: specify the condition, consisting of attribute/value pairs and comparison operators. Attribute names can be selected by means of a pop-up menu. Currently following conditions are supported:
    1. [attribute] is [value | video object ]
       This condition results in the return of video-object which have the specified attribute value or video-object.
       example
    2. [attribute] contains [value | video object]
       It stipulates to return video-objects which contain the specified value or the specified video-object in the set value of the specified attribute.
    3. definedOver [ video sequence | video frame ]
       This condition orfers the return of video-objects that are defined over the specified video frame sequence or frame.
       
       For example:    definedOver frame(15000)
       causes the retrieval of the video-objects which include the video frame with frame#:15000 in their defined video sequence.



Figure 12. The selection of one of the retrievals.



• Other features of VideoSQL
  • VideoSQL can formulate more than one query and savetheir retrival results at the same time.
  • Retrived video-objects are able not only to be replayed, but to become operands of the Merge operation as well.
  • How to display the query, see figure.
    click the Merge button to merge several video-objects from different retrieving results.


• Extensions of VideoSQL
  
  • Temporal arrangement and composition of retrieved data The temporal arrangementof video/audio data is specified in the time subclause in the select clause of a VideoSQL query.
  • Spatial arrangement and composition of retrieved data : specified in the space subclause.
  • Special effect for retrieved data Temporally- and spatially- arranged retrieved video/audio data can be displayed with several special visual effects, such as mosaic, fade-in/out, etc. These are specified in the option subclause.
  • Example:
    select window1 { time{ start(A, B); follow(A, C); startstart(C, D(t));
    Worldtime(A: 0, *) } space{ +50+50@200*100 }
    option{ A:fast } }
    window2{ time{ Worldtime( A:3, 10);
    follow(A, F);
    end(E, F) }
    space{ +300+300@150*60 }
    option{ F: fade-in } }
    from Video A, C, F;
    Audio B, D, E;
    where A.car = 'skyline' and C.car = 'corona' and
    B.title = 'yesterday' and D.title = 'freedom' and
    E.creature = 'dog' and F.title = 'thriller'
    
• Decomposing(disaggregating) video-objects.
  
• Moving to the cideo object definition tool and VideoSQL.
  
  

Figure 13. An example retrieval for both audio and video objects.