If the image has been stored in MPEG-2 format, and if the SCU has knowledge independent of DICOM as to which section of a “video” is required for viewing (e.g. perhaps notes from an endoscopy) then the SCU can perform the following steps:
Use known configuration information to identify the available transfer syntaxes
If MPEG-2 or JPEG 2000 Part 2 Multi-component transfer syntaxes are available, then issue a request to retrieve the required section.
The data received may be slightly longer than that requested, depending on the position of key frames in the data.
If only other transfer syntaxes are available, then the SCU may need to retrieve most of the object using Composite Instance Retrieve Without Bulk Data Retrieve Service to find the frame rate or frame time vector, and then calculate a list of frames to retrieve as in the previous sections.