Operating the Equipment Locally — Setup Menu: Video Menu
Reference Guide: Voyager E5784 and E5788 HD DSNG Encoder
Page 4-45
ST.RE.E10137.3
Table 4.36: VBR Mode Options
Selected Option
Description
Off <constant>
VBR mode not selected. Any unused bits are stuffed.
On <stuffing off>
This uses normal quantisation levels and any unused bits are used to carry other data. This
has no impact on the quality of the encoded pictures.
On <variable>
Quantisation level is limited with pictures which are easier to encode. This is done in order to
provide more unused bits to carry other data. This may have an impact on the quality of
certain encoded pictures.
VBR Mode (SD Only) Option
This option is only available from the
Systems Menu
when the
M2/ESO2/VBR licence key is purchased.
It is possible to operate the Encoder in a stand-alone Variable Bit-rate
(VBR
6
) mode. When in this mode the bit-rate generated by the video
encoder ranges between a minimum (Bmin - dependent on Compression
Mode) and a maximum (Bmax - set by user, up to a limit defined by the
Compression Mode). The video encoder attempts to use a bit-rate to
achieve a particular picture quality set by the user.
If this is set very high then the generated bit-rate clips at the Bmax value.
If it is set very low then the bit-rate clips at Bmin. Somewhere in-between
the bit-rate varies, depending on the picture material being encoded.
Simple pictures use a lower bit-rate than complex pictures.
When in this mode the main encoder output remains at the bit-rate set
within the Mux menu and any spare unused bit-rate is filled with stuffing
packets. These could optionally be removed and reinserted by some
equipment between the Encoder and Decoder.
A typical view of the Video Encoder menu would be:
To run in VBR mode the Encoder must be placed into a Seamless
Compression mode.
A new menu item VBR Mode then appears. When set to Off (Constant)
the Encoder generates a fixed constant bit-rate set by the Bit-rate option.
When changed to On (Variable) the Encoder enters its stand-alone
VBR Mode.
6
The VBR licence M2/ESO2/VBR is needed with this option.
