Optelecom-nkf Siqura C-54 E-MC User Manual page 43

Using the internal web pages
Video bit rate
mode
Resolution
GOP length
Frame rate
Controls variations in bit rates. For a concise explanation, consult the
note on encoder settings below.
MPEG-4 encoding mode supports the following bit rate modes.
- Constant quality
- Variable bit rate
- Variable bit rate non-drop
- Constant bit rate
- Constant bit rate non-drop
MPEG-2 encoding mode does not support variable bit rate modes. The
value of this parameter is set to Constant bit rate non-drop.
MJPEG encoding mode supports Constant quality and Constant bit rate.
Supported resolutions are D1, 1/2 D1, 2/3 D1, 2CIF, CIF, QCIF, VGA
(640x480), and QVGA (320x240). See also table 7.1.
Per video input, the C-54 E will simultaneously handle dual MPEG-2/4
encoding (MPEG-2 in I-frame only) with 1xD1 and 1xCIF or 2CIF at full
frame rate, and Live View encoding at 5 frames per second.
Setting Encoder 1 and Encoder 2 to perform MPEG-4 encoding in D1
resolution at the same time may overtax the hardware.
resolution (hxv)
D1
2/3 D1
1/2 D1
2CIF
CIF (top field only)
QCIF
Table 7.1 C-54 E MPEG-2/4, MJPEG resolutions
Note on CIF resolutions: CIF resolutions (2CIF, CIF, QCIF) use only one of the
two frame fields. When CIF resolution encoded pictures are displayed on a
monitor, the decoder has to simulate the second field (by extrapolation from the
first field) in order to present two frame fields. Here, CIF is mostly used for
recording purposes, as a compromise between video quality and resolution.
Distance in frames between two I-frames. This setting is only available in
MPEG-4 encoding mode.
Selectable rates are determined by the video mode (PAL, NTSC) set on
the General tab. PAL: 1-25 fps; NTSC: 1-30 fps. Note that VLC and
QuickTime only support full frame rates for MPEG-2, Transport Stream.
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Keeps image quality constant at the cost
of varying network load.
Same as constant bit rate (see below),
but bit rate is constant for a limited time,
allowing the encoder to use more bits for
difficult GOPs. Frames may be skipped.
Same as variable bit rate. Frames are
never skipped.
Keeps network load constant at the cost
of varying image quality. Frames may be
dropped.
The same as Constant bit rate. Frames
are never skipped.
PAL NTSC
720x576 720x480
480x576 480x480
352x576 352x480
720x288 720x240
352x288 352x240
176x144 176x120