ILMMP42Encoder

This is the interface for the LEAD MPEG-4 Encoder.

Data Types

eEncodingThreads

typedef enum  
{ 
   LMP4_THREAD_AUTO, 
   LMP4_THREAD_1, 
   LMP4_THREAD_2, 
   LMP4_THREAD_3, 
   LMP4_THREAD_4, 
   LMP4_THREAD_5, 
   LMP4_THREAD_6, 
   LMP4_THREAD_7, 
   LMP4_THREAD_8, 
} eEncodingThreads; 

Lists the possible encoding threads number that can be set on the property EncodingThreads.

Enumeration Description
LMP4_THREAD_AUTO Have the LEAD MPEG4 Encoder determine the appropriate number of threads.
LMP4_THREAD_1 Use 1 thread during encoding.
LMP4_THREAD_2 Use 2 threads during encoding.
LMP4_THREAD_3 Use 3 threads during encoding.
LMP4_THREAD_4 Use 4 threads during encoding.
LMP4_THREAD_5 Use 5 threads during encoding.
LMP4_THREAD_6 Use 6 threads during encoding.
LMP4_THREAD_7 Use 7 threads during encoding.
LMP4_THREAD_8 Use 8 threads during encoding.

eEncodingPassesCount

typedef enum  
{ 
   LMP4_ENCODINGPASSESCOUNT_ONE, 
   LMP4_ENCODINGPASSESCOUNT_TWO, 
} eEncodingPassesCount; 

Lists the possible encoding passes counts.

Enumeration Description
LMP4_ENCODINGPASSESCOUNT_ONE Use 1 pass mode in encoding.
LMP4_ENCODINGPASSESCOUNT_TWO Use 2 passes mode in encoding.

eCompressionMode

typedef enum  
{ 
   LMP4_COMPRESSIONMODE_ConstantQuality, 
   LMP4_COMPRESSIONMODE_VariableBitrate, 
   LMP4_COMPRESSIONMODE_ConstantBitrate, 
} eCompressionMode; 

Lists the possible values for the compression mode.

Enumeration Description
LMP4_COMPRESSIONMODE_ConstantQuality Uses the QFactor property value to regulate the image quality.
LMP4_COMPRESSIONMODE_VariableBitrate Varies the quality over short durations. However, it will achieve an average rate matching the BitRate property value.
LMP4_COMPRESSIONMODE_ConstantBitrate Strictly adheres to the rate specified in the BitRate property.

eOutputFormat

typedef enum  
{ 
   LMP4_OUTPUTFORMAT_mp4v, 
   LMP4_OUTPUTFORMAT_LMP4, 
   LMP4_OUTPUTFORMAT_XVID, 
   LMP4_OUTPUTFORMAT_iPod, 
} eOutputFormat; 

Lists the possible values for the output format.

Enumeration Description
LMP4_OUTPUTFORMAT_mp4v Make the encoder output type the Standard MPEG4 video media subtype.
LMP4_OUTPUTFORMAT_LMP4 Make the encoder output type the LEAD proprietary MPEG4 video subtype. This allows super compression to be used.
LMP4_OUTPUTFORMAT_XVID Make the encoder output type the XVID video subtype.
LMP4_OUTPUTFORMAT_iPod Make the encoder output compatible with iPod devices.

eQuantType

typedef enum  
{ 
   LMP4_QUANTTYPE_Linear, 
   LMP4_QUANTTYPE_NonLinear, 
} eQuantType; 

Lists the possible values for the quantization method to be used by the encoder.

Enumeration Description
LMP4_QUANTTYPE_Linear Use H.263 quantization.
LMP4_QUANTTYPE_NonLinear Use MPEG quantization.

eMotionAccuracy

typedef enum  
{ 
   LMP4_MOTIONACCURACY_FullPixel, 
   LMP4_MOTIONACCURACY_HalfPixel, 
} eMotionAccuracy; 

Lists the possible values for the Motion estimation accuracy.

Enumeration Description
LMP4_MOTIONACCURACY_FullPixel One pixel accuracy.
LMP4_MOTIONACCURACY_HalfPixel Half pixel accuracy (faster).

eMotionAlgorithm

typedef enum  
{ 
   LMP4_MOTIONALGORITHM_FullSearch, 
   LMP4_MOTIONALGORITHM_FastSearch, 
} eMotionAlgorithm; 

List the possible values for the motion algorithm. (the algorithm to be used when determining if motion is occurring).

Enumeration Description
LMP4_MOTIONALGORITHM_FullSearch Use the full motion search algorithm (testing all possibilities). This option slows down the encoding process considerably.
LMP4_MOTIONALGORITHM_FastSearch Use fast motion search.

eMotionVectorPerMacroblock

typedef enum  
{ 
   LMP4_MOTIONVECTOR_OnePerMacroblock, 
   LMP4_MOTIONVECTOR_FourPerMacroblock, 
} eMotionVectorPerMacroblock; 

List the possible values for the motion vectors (vectors to be used in the motion estimation algorithm).

Enumeration Description
LMP4_MOTIONVECTOR_OnePerMacroblock Use one motion vector (fast).
LMP4_MOTIONVECTOR_FourPerMacroblock Use four motion vectors (better quality, slower encoding).

Properties

Type Name Description
long QFactor The quality factor used in compressing the video stream; the lower the quality factor, the better the quality. Possible values range from 1 (best) to 31 (worst).
eQuantType QuantType The quantization method applied.
double OutputFrameRate The desired output frame rate, in frames per second. Possible values range from 1.0 to 30.0. Pass -1 to make the output frame rate the same as the input frame rate.
eOutputFormat OutputFormat The encoder output type.
VARIANT_BOOL SuperCompression Enables/disables super compression, LEADs improvement to the MPEG4 video compression. When super compression is used, compressed video size is reduced noticeably with almost the same quality, and the encoding and decoding speed is enhanced. Files generated using this option, will not be MPEG4 compliant: they can be decoded only by the LEAD MPEG4 Video Decoder. Possible values are:
• VARIANT_TRUE - Enable super compression. This is allowed only if the output format is set to LMP4_OutputFormat_LMP4.
• VARIANT_FALSE - Disable super compression.
long PFrames Specifies the number of P frames between two successive I frames. *
long BFrames Specifies the number of B frames between two successive P frames. *
long SearchWidth The search block width used when determining if motion is occurring. The larger the block, the slower the encoding process. It is not recommended to use large values. The range is from 2 to the video stream width, in pixels.
long SearchHeight The search block height used when determining if motion is occurring. The larger the block, the slower the encoding process. It is not recommended to use large values. The range is from 2 to the video stream height, in pixels.
eMotionAlgorithm MotionAlgorithm The algorithm to be used when determining if motion is occurring.
eMotionAccuracy MotionAccuracy Motion estimation accuracy.
eMotionVectorPerMacroblock MotionVectorPerMacroblock Specifies how many motion vectors are used in the motion estimation algorithm.
eEncodingThreads EncodingThreads The number of threads used during encoding. The maximum number of threads that can be used is 8. Using multi threads with a multi core machine or multi CPUs will increase the encoding speed significantly.
VARIANT_BOOL InsertVOL Set to VARIANT_TRUE to insert a mpeg4 header before each I-frame. This is useful in a video broadcasting where the mpeg4 decoder might start decoding from the middle of the stream.
VARIANT_BOOL InsertGOV Set to VARIANT_TRUE to insert an optional header before I frames that indicates to the decoder the timestamp of the I frame and whether it is open/closed GOV. This helps the stream to be randomly seeked in some decoders. However, the LEAD MPEG4 decoder does not require it.
eCompressionMode CompressionMode Sets the compression mode.
long BitRate This is the average or constant bitrate used when the CompressionMode is set to LMP4_COMPRESSIONMODE_VariableBitrate or LMP4_COMPRESSIONMODE_ConstantBitrate. The value is in bits per second.
eMotionAccuracy MotionAccurancy Motion estimation accuracy.
VARIANT_BOOL Interlacing Set to VARIANT_TRUE to encode the video as interlaced fields. Otherwise, the video is encoded as frames. The default is VARIANT_FALSE.
long SceneChangeThreshold The threshold that determines a scene change point in a video clip. The encoder calculates this value for every inter-frame being encoded. If the calculated value is greater than threshold then it is a scene-change point and the frame will be encoded as an I-frame. this value should be between 1 and 100 and default is 50, (values between 30-50 gives the best compression result). To turn off this feature Scene Change Detection, should be set to 100.
eEncodingPassesCount EncodingPasses Specifies the number of encoding passes.

Methods

HRESULT ResetToDefaults();

Description

Resets the filter properties to their default values. Calling this method can cause the filter to reconnect its output pin. The default values are:

Property Default value
OutputFrameRate -1.0
PFrames 9
BFrames 0
OutputFormat LMP4_OUTPUTFORMAT_mp4v
BitRate 300000
interlaced VARIANT_FALSE
InsertVOL VARIANT_TRUE
insertGOV VARIANT_FALSE
SceneChangeThreshold 50
EncodingPassesCount LMP4_ENCODINGPASSESCOUNT_ONE
EncodingThreads LMP4_THREAD_1
CompressionMode LMP4_COMPRESSIONMODE_ConstantQuality
MotionVectorPerMacroblock LMP4_MOTIONVECTOR_OnePerMacroblock
MotionAccuracy LMP4_MOTIONACCURACY_FullPixel
MotionAlgorithm LMP4_MOTIONALGORITHM_FastSearch
QuantType LMP4_QUANTTYPE_Linear
QFactor 4
SuperCompression 0
SearchHeight 16
SearchWidth 16

Returns

Return Description
S_OK Successful.
< 0 An error occurred.
VFW_E_WRONG_STATE The filter is in the wrong state.

HRESULT WriteToRegistry();

Description

Writes the values of all of the properties listed above to the system registry, so that the decoder will remember these settings the next time it is used.

Comments

This method is automatically called by the property page when you apply modified settings by clicking on the Apply or OK button.

Returns

Return Description
S_OK Successful.
< 0 An error occurred.

* To increase compression performance, MPEG4 uses Temporal Compression. Temporal compression is achieved by only encoding the difference between successive frames instead of the frames themselves. This means that frames cannot be considered in isolation. A given picture is constructed from the prediction from a previous picture, and may be used to predict the next picture. An MPEG-4 video stream is comprised of I Frames, B Frames and P Frames:

So to increase the compression of MPEG-4 more B and P frames should be used by adjusting PFrames and BFrames properties.

Help Version 22.0.2022.4.7
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© 1991-2022 LEAD Technologies, Inc. All Rights Reserved.