The following table describes
MPEG-4 Video Encoder Advanced Settings
controls.
Table 15.
MPEG-4 ASP Video Encoder Advanced Settings Controls
Control
Description
Scene change detection
Enables/disables the scene change detection (SCD) mode. This feature causes
the Encoder to insert I-frames when new scenes are detected. If this option is
enabled (recommended), the encoded stream quality and positioning precision
are improved.
Adaptive GOP
Enables/disables the adaptive GOP structure. When the video complexity is
very high, the encoder decreases number of B-frames to increase the encoding
quality. Recommended for permanent use.
Max rate
Specifies the maximal stream bitrate. Relevant only to the variable bitrate
(VBR) mode.
Buffer size
Specifies the video buffer size. If the value is equal to zero then the encoder
automatically calculates the required buffer size.
Skip frames for VBV
compliance
Enables the encoder to respect VBV buffer underflow restriction by producing
fake frame all block of which are skipped. Reduces quality while maintaining
VBV compliance. It is recommended to select this option, when encoded video
is intended for playback on particular devices (VBV model maintenance is
obligatory) or for network broadcasting (fixed bandwidth).
Field order
Specifies the order of fields in the encoded video stream.
Quantizer for I/P/B slice
in CQ mode
Spesifies the quantizers for I-frames (reference frames), P-frames (predicted
frames) and B-frames (bidirectional predicted frames) in the CQ (Constant
Quantizer) mode.
Quantization mode
Specifies the quantization scale type. During compression process the discrete
cosine transformation (DCT) is performed on video data. The DCT coefficients
are maked more coarse using division. The divisor is named quantizer.
•
H263
– fixed (constant) quantizer. The same quantizer is used for all
coefficients.
•
MPEG
– non-linear quantizer. Higher frequencies (are responsible for
fine details) are usually quantized more coarsely (fewer values allowed)
than lower frequencies. It provides higher compression, while video
quality is degraded insignificantly.
Adaptive motion
estimation
Allows the encoder to improve output video quality, when interlaced stream is
encoded. The encoder checks which motion estimation mode (frame or field) is
more effective for each macro-block. The checking procedure decreases the
encoding speed. This option is useful, when quality is more significant than
speed. It is recommended to use for encoding of interlaced video with both
static (progressive mode provides better result) and dynamic (interlaced mode
is more suitable) scenes.
Chroma motion
estimation
Enables the encoder to calculate motion vectors using the chromatic
components of picture. The more informative chromatic fields allow the more
efficient motion estimation. This option is useful, when quality is more
significant than speed.
Use 4MV
Enables usage of blocks less than 16x16 in the motion estimation process. It
insreases the motion prediction accuracy. Recommended for use.
Alternative vertical scan
Enables the encoder to use alternative vertical scan instead of standard zigzag
scan. Provides more efficient grouping of video data before DCT and (as a
result) improves the quantization efficiency. This option is useful for pictures
with significant correlation of vertically aligned components (such as grouped
fields of interlaced video). It increases probability of long sequences of equal
quantized coefficients and consequently provides better compression. Does not
affect the encoding speed. It is recommended to use in interlaced video
encoding.
Short header
Provides compatibility of MPEG-4 Visual with the ITU-T H.263 video coding
standard. A lot of MPEG-4 specific features ( for example, B-frames) will be
disabled. Produced video stream will contain the H.263 FOURCC mark.
It is recommended to select this option, when encoded video is intended for
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