User manual

Introduction : Buffer & Cache Tab
Page 21
Read Drop Counter
The Read Drop Counter shows a continuous display of how many frames of video were dropped (due to insuffi-
cient throughput of the media volume to the VCube playback engine) during a single playback pass. If the raw
media data arrives late to VCube because the disks are too slow, then VCube does not even have a chance to pro-
cess them.
Note: Stopping and restarting playback resets the values in all the counters so consult them dur-
ing playback.
Read Time Average
The Read Time Average shows the delay of processed video frames (post playback engine) from disk-to-Playback
Engine to the Playback Buffer. This value must never exceed the Safe Delay values listed above for a succession of
frames larger than the size of the Number of Frames in the Playback Buffer. If it does the result is a playback stall.
Preview Drop Counter
The Preview Drop counter shows the number of frames dropped in the VCube Preview Window running on the
display engine of the computers graphic board (as opposed to video frames dropped on the AJA board shown in
the Video Drop counter). When in doubt as to if VCube is dropping frames, consult this counter during playback.
It is also displayed at the lower left-hand side of the VCube interface Drop=0.
Current FPS
The Current FPS counter shows the real-time frame rate per second of the VCube playback engine. If this value
varies after the initial lock cycle of VCube is established then VCube has detected a drift in the playback speed.
This is most likely due to a problem between the lock reference of VCube and the incoming TimeCode value. It
may also be due to a conflict between the frame rate of VCube and that of Pyramix or Virtual Transport.
Remedy: Verify that all three are running at the same frame.
Buffer & Cache Tab
The Buffer and Cache Tab located on the Settings Page is crucial to the proper setup of VCube and, as discussed
in the previous section, must be carefully adjusted for the type of Media being played back by VCube.
It has been found that the best general default parameters are:
1. Start with a Buffer value of 7 for SD picture and 15 for HD picture
2. Deactivate all four of the read and write caches and restart VCube for the cache changes to take effect.
Adjustments may be made to facilitate certain HD files that prove to be problematic during playback but the
Buffer itself should be gradually increased and not just set to it's maximum value at all times which (like any buffer)
may seriously hinder the performance and reliability of the system by consuming excessive amounts of precious
RAM, especially on a 32-bit operating system.
Note: The Multi Thread Seeking button has negligible effect due to the vast improvements in IT
hardware in general since the introduction of VCube v1.0 and may be left off.
For further detail and contact information visit Merging Technologies' website:
www.merging.com