Loop through, e to e, and feeds, Recording synchronous and asynchronous feeds – Grass Valley K2 System Guide v.9.0 User Manual
Page 45
Real Time system — Manages the media flow between the Storage system and the inputs and outputs.
The Real Time system has dedicated processors and time-sensitive mechanisms to serve media
processing needs while maintaining real-time accuracy.
When you control play and record operations from within the Application system you trigger a chain
of events that eventually crosses over into the Real Time system and results in media access. The
following sequence is an example of this type of chain of events:
1. A user operates the Player application to play a particular clip. The Player application asks the
Media File system for permission to access the clip. The Media File system grants access. In
shared storage models, the Media File system enforces shared storage policies in order to grant
the access. When access is granted, the Player application initiates play access to the clip.
2. The database identifies the files that make up the clip and the file system instructs the Storage
system to open access to the files.
3. The Storage system finds the raw data and opens the appropriate read access. At this point both
the Application system and the Real Time system are involved. Windows controls the media
drives and controllers, so the Real Time system makes file requests to Windows and it causes
the data to be transferred to buffers on the Real Time processor. The data is then available to the
Real Time system so that it can be processed at exactly the right time.
4. The Real Time system processes the media, decompresses it, adjusts its timing, and moves it as
required to play the clip as specified by the user.
Loop through, E to E, and feeds
Behaviors related to input signals routed to output connectors are described in the following topics.
Related Topics
on page 209
Recording synchronous and asynchronous feeds
For best results in all workflows, use synchronous feeds, defined as follows:
•
All outputs are locked to the house reference
•
All inputs are genlocked to the house reference and at zero time
The K2 Summit Production Client and K2 Solo Media Server can record inputs that are asynchronous,
with the following considerations:
•
The encoder clock and the audio clock are derived from the input signal, which enables frame
accurate recording of all inputs.
•
Outputs are timed to the reference and if no reference is present, the output runs free.
•
If the input video rate does not equal the output video rate (asynchronous) then video tearing or
jumping can occur when input/output synch is critical, such as in the following:
•
K2 TimeDelay
•
SD-00 or Summit E-to-E (LoopThru) mode
•
HD-00 Loopback
06 November 2012
K2 System Guide
45
Product description