ILMH263Encoder Interface

PERFECTQUALITY

[0] Very good quality.

Equivalent to a custom quality factor of 4.

QUALITYSIZEEQUALLYIMPORTANT

[2] Good quality, more compression than QUALITYMOREIMPORTANTTHANSIZE.

Equivalent to a custom quality factor of 6.

HIGHESTCOMPRESSION

[4] Highest compression (lowest quality).

Equivalent to a custom quality factor of 31.

MODEM_56K

[0] 56K modem. Equivalent to a bitrate of 56000.

ISDN_256K

[2] 256K ISDN line. Equivalent to a bitrate of 256000.

CABLE_768

[4] 768K Cable line. Equivalent to a bitrate of 768000.

WIRELESS_802_11B_11M

[6] Wireless 801.11b network card. Equivalent to a bitrate of 11000000.

WIRELESS_802_11G_54M

[8] Wireless 801.11g network card. Equivalent to a bitrate of 54000000.

LAN_1G

[10] 1Gbps network card. Equivalent to a bitrate of 1000000000.

HIGHQUALITY

[0] High quality option. Turn on all settings.

QUALITYSPEEDEQUALLYIMPORTANT

[2] Compromise between quality and speed. Only the Unrestricted MV and Advanced Prediction modes are turned on.

HIGHSPEED

[4] Highest speed. No optional mode is turned on.

UNIT_FRAMES

[0] The unit for the IDistance property is frames.

long

MINQUALITYFACTOR

[1] The minimum value for CustomQuality . This generates the highest quality video and the lowest compression.

H263COMPATIBILITY_DEFAULT

[0] Default mode: all encoder settings are enabled.

H263_APILEVEL_1

[0] Use the defaults from the previous version of the codec. This APILEVEL's defaults include setting the IDistanceUnit property to UNIT_SECONDS and the IDistance property value to the default value of 60, yielding 1 key frame every 60 seconds.

VARIANT_BOOL

UseQuality

Set to TRUE to use quality-based compression (VBR = variable bitrate). In this case, the quality is given by the UsePredefinedQuality, PredefinedQuality and QualityFactor properties.

Set to FALSE to use bitrate-based compression (CBR = constant bitrate). In this case, the bitrate is given by the PredefinedBitrate and BitrateValue properties.

eQUALITY

PredefinedQuality

(Used only if UseQuality is TRUE and UsePredefinedQuality is TRUE). Use this property to choose one of the predefined quality options. See the eQUALITY enumeration for possible values.

VARIANT_BOOL

UsePredefinedBitrate

(Used only if UseQuality is FALSE). Set to TRUE to use a predefined bitrate through PredefinedBitrate .

Set to FALSE to use a custom bitrate through CustomBitrate .

long

CustomBitRate

(Used only if UseQuality is FALSE and UsePredefinedBitrate is FALSE). Use this value to set the desired compressed video rate in bits per second.

eSPEED

PredefinedSpeed

(Used only if UsePredefinedSpeed is TRUE). Use this property to set the speed to one of the predefined values. See the eBITRATE enumeration for possible values.

VARIANT_BOOL

UseDeblockingFilter

(Used only if UsePredefinedSpeed is FALSE). If TRUE, the blocky artifacts generated at higher compression are reduced by using an adaptive filter across block boundaries. Use this option to improve the video quality at low bit rate (high compression). Implements (Annex J) Deblocking Filter mode of the ITU-T Recommendation H.263 and LEAD H.263 Encoder.

VARIANT_BOOL

UseAdvancedPredictionMode

(Used only if UsePredefinedSpeed is FALSE). If TRUE, Overlapped Block Motion Compensation (OBMC) is used for the luminance part of P-pictures. Four 8x8 vectors instead of one 16x16 vector are used for some of the macroblocks in the picture. The encoder has to decide which type of vectors to use. Four vectors use more bits, but give better prediction (compression). Implements (Annex T) Modified Quantization mode of the ITU-T Recommendation H.263 and LEAD H.263 Encoder. Implements (Annex F) Advanced Prediction mode of the ITU-T Recommendation H.263 and LEAD H.263 Encoder.

float

OutputFrameRate

Use this property to control the output frame rate. You can set the output frame rate to be the same as the input frame rate (-1) or you can set it to particular output frame rate (if > 0). Note that you should set the output frame rate to be less than the input frame rate (to get better compression). It is not very useful to set the output frame rate to the less than the input frame rate.

VARIANT_BOOL

UseSuperCompression

Set to TRUE, to enable the high compression mode, which is a non-standard extension introduced by LEAD Technologies, Inc. to the H.263 compression algorithm. This generates a smaller video, but only the LEAD H.263 Decoder can decode this video. The video generated in this mode has a small quality degradation (especially when there is text), but the compression gain is significant. This mode is very useful for achieving lower bitrates.

Set to FALSE to disable this mode. The default is FALSE.

long

IDistance

Use this to set the interval for I frames. The IDistanceUnit property contains the unit for this property (seconds or frames). The distance between two consecutive I frames is sometimes referred to as the Key Frame interval. I (Intraframe) frames are encoded independently without any reference to a previous frame or forward frame. All the frames between I frames are P and B frames. P (Predictive) frames are encoded using the previous frame as reference. P frames are compressed more than I frames. B (Bi-directional) frames are encoded using both the previous and the next frames as reference and they are compressed better than I and P frames.

If the distance between I frames increases, the compression ratio increases. However, a large distance between I frames has its disadvantages:

• If an I frame is lost before reaching the decoder (typically due to a noisy or an unreliable channel), the decoder has to wait a long time without displaying anything until the next I frame comes.

• A large key frame interval makes seeking (searching through the video data) slower.

VARIANT_BOOL

SorensonOutput

Set to TRUE, to generate Sorenson video used by Flash ( FLV ) files. This video is a modified form of H.263 compression. Set to FALSE to generate regular H.263 video. The default value is FALSE.