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JPEG2000 Formats MDR Setting
The Maximum Data Rate (MDR) setting for JPEG2000 image formats are defined in Megabits per second or
Mbits/sec. This convention is used to reflect the terminology used by the Digital Cinema industry. Currently, only the
250Mbit/sec value is defined for Digital Cinema JPEG2000 formats. This value corresponds with the maximum data
rate (in megabits) defined by current Digital Cinema standards.
Clip Form
There are two primary clip form types: collapsed and expanded. The form of the media file dictates how the video
and audio assets of a media file are physically stored on disk. The other important element that is dictated by clip
form is whether or not the media file can be used in an editing environment.
Collapsed – Media files that are “collapsed” have both audio and video assets interleaved together in a
single file. Collapsed media files are typically used to distribute a completed project as a single playable
media object.
Expanded – Media files that are “expanded” use separate files to store video and audio assets. Expanded
media files that belong together share a common base name but have different file extensions to indicate
the stored asset, video (.v) or audio (.a).
Expanded audio assets have additional flexibility that allows QuVIS video servers to store audio assets as
either a collection of all audio channels (cluster) or as individual audio tracks (discrete channels) stored in
separate files. An “audio cluster” is designated with a file extension of “.a” or “.wa: (QuVIS broadcast wave
format). “Audio tracks”, stored in separate files, are designated by a “.ann” file extension where “nn”
indicates the audio channel number the file was recorded on.
Expanded media files are structured to enable real-time editing using a QuVIS Virtual Tape editing object.
Virtual tapes enable QuVIS video servers to emulate a traditional linear tape editing process while
providing the additional flexibility of a digital workflow.
MXF (Digital Cinema ) – Media files that have been loaded from a Digital Cinema Package (DCP) are
stored on the QuVIS Acuity in a special expanded clip format. Composition image and audio files are
identified by their naming structure, which end in “_video.mxf” and “_audio.mxf”.
Virtual Tapes
A QuVIS Virtual Tape (or VTP) emulates a traditional pre-striped videotape (a pre-formatted tape containing video
black and timecode) for editing in a post-production environment. Virtual tapes are editable media object that may
be created and edited only by a QuVIS mastering server (QuVIS Acuity, QuVIS Encore and QuBit ST). All current
QuVIS video servers (QSR 2.3 or greater) can be used to play virtual tapes. Offline clip tools, such as the
Modclip
command, may be used to create other playable media files (including collapsed clips) using a VTP file (or timeline
file) as the source.
Virtual tapes let you record and edit content directly on the QuVIS mastering server as though it contains a fixed-
length, striped videotape. Unlike traditional linear tapes, the recorded edits or media assets of a VTP are stored in
their entirety as clip files and the edit points are managed independently in the VTP container file.
Editing a VTP is a non-destructive process, meaning that when an edit is performed a new asset or clip is created
and does not overwrite existing data. Instead of overwriting any data on the VTP, a new set of pointers within the
VTP container file are created to point to the location of the new content.
Virtual tapes can be used for both QPE and JPEG2000 projects although these encoding formats cannot be
intermixed within the same VTP. Likewise, virtual tapes can be used with any supported image resolution and frame
rate provided that all of the content used matches the format settings of the VTP.
A VTP consists of several elements:
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