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Appendices : MPEG Settings (MainConcept Encoder) Page 253
(but a very large number of bits). If you set all numbers of the matrix to 255, you will obtain a very bad picture
because it has been compressed to such a degree that it will lead to a significant loss of quality.
When you activate the User quant matrices checkbox you can click the Edit button in order to adjust the param-
eters for Matrix for Intra Block and Matrix for non-Intra Block. In the following window you can change these set-
tings.
These values must be in the range 16 ... 256, with the exception that the first entry in the intra block matrix must
be 8. Intra blocks are macroblocks coded using only information from the current picture (I frames), non-intra
blocks are macroblocks coded using information from the current picture and other pictures (B and P frames). If
the bitrate is high you should not change the parameters. Ultimately, these values depend on the source material.
If the bitrate is low you can change the parameters to get better results.
Additional Settings
The different options are displayed in the tree. You can change the settings by using the Value parameter box.
Depending on the setting you have to adjust the appropriate option in the corresponding tree. A short definition
of the selected option is offered under the display.
Under Sequence Header you find the following option:
VBV Buffer size: This value specifies the size of the Video Buffering Verifier (VBV) buffer in KB (1024 bytes). Decod-
ers can use this value to determine the largest buffer needed to decode the video stream. Set it to zero to have the
encoder compute a value based on the video bitrate. VCD specifies 40 KB, SVCD and DVD specify 224 KB. Use the
Value prompt in order to change the parameters. See ISO/IEC 13818-2 or ISO/IEC 11171-2.
The option Sequence Extension offers two settings:
Progressive Sequence: If set to 1 all frames in the video are progressive, if set to 0 both progressive and inter-
laced frames can appear in the video. See ISO/IEC 13818-2. This option is only valid for MPEG-2.
Chroma Format: The option specifies whether to use the 4:2:0 or 4:2:2 (high profile only) chroma format for the
encoded video. See ISO/IEC 13818-2. Only the 4:2:0 and 4:2:2 formats are supported. This option is only valid for
MPEG-2.
Under Sequence Display Extension you can edit several options:
Enable Sequence Display Extension: If set to 1, sequence display extension headers are placed in the video
stream after the sequence extension headers. If set to 0, the Video format, Color Primaries, Transfer characteristics,
Matrix coefficients and Display Size settings are not used or present in the video stream. Some SVCD players can
have problems if sequence display extensions are present, for DVD the sequence display extension may or may
not be present. See ISO/IEC 13818-2.