Dirac - A Video Codec
Created by the British Broadcasting Corporation.
dirac::ModeDecider Class Reference
Decides between macroblock and block prediction modes.
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#include <me_mode_decn.h>
Collaboration diagram for dirac::ModeDecider:
[legend]List of all members.Public Member Functions
Private Member Functions
- ModeDecider (const ModeDecider &cpy)
- ModeDecider & operator= (const ModeDecider &rhs)
- void DoMBDecn ()
- void DoLevelDecn (int level)
- Make a mode decision given a particular level of decomposition.
- float DoUnitDecn (const int xpos, const int ypos, const int level)
- Decide on a mode for a given prediction unit (block, sub-MB or MB).
- float DoCommonMode (PredMode &predmode, const int level)
- Choose a common mode for all units in a MB assuming a particular level of decomposition.
- void DoME (const int xpos, const int ypos, const int level)
- Do motion estimation for a prediction unit at a given level.
- float ModeCost (const int xindex, const int yindex, const PredMode predmode)
- Return a measure of the cost of coding a given mode.
- ValueType GetDCPred (int xblock, int yblock)
- Get a prediction for the dc value of a block.
- float GetDCVar (const ValueType dc_val, const ValueType dc_pred)
- Get a measure of DC value variance.
Private Attributes
Detailed Description
Loops over all the macroblocks and decides on the best modes. A macroblock is a square of 16 blocks. There are three possible splitting levels: level 0 means the macroblock is considered as a single block; level 1 means the macroblock is considered as 4 larger blocks, termed sub-macroblocks; level 0 means the macroblock is split right down to blocks.
In addition there is a common_ref mode which if true means the prediction mode of all units within the MB are the same (e.g. all sub-MBs are predicted only from reference 1). In deciding which modes to adopt, the ModeDecider object calculates costs for all permutations, doing motion estimation for the level 1 and level 0 modes as these have not been calculated before. The process of decision for each is as follows. For each MB, we loop over the levels, and call DoLevelDecn. DoLevelDecn does motion estimation if it's necessary. Then it assumes that we don't have a common block mode and calls DoUnitDecn which finds the best mode for each unit in the MB at that level, individually. Then we consider the case where we say that all the modes will be the same, and call DoCommonMode to see if we'll get a lower cost. Then when we've got a best cost for that level we go up to the next one.
Constructor & Destructor Documentation
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The constructor creates arrays for handling the motion vector data at splitting levels 0 and 1, as motion estimation must be performed for these levels. |
dirac::ModeDecider::~ModeDecider |
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The destructor destroys the classes created in the constructor |
dirac::ModeDecider::ModeDecider |
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const ModeDecider & |
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Member Function Documentation
float dirac::ModeDecider::DoCommonMode |
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PredMode & |
predmode, |
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const int |
level |
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void dirac::ModeDecider::DoLevelDecn |
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int |
level |
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void dirac::ModeDecider::DoMBDecn |
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void dirac::ModeDecider::DoME |
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const int |
xpos, |
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const int |
ypos, |
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const int |
level |
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void dirac::ModeDecider::DoModeDecn |
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const FrameBuffer & |
my_buffer, |
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int |
frame_num, |
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MEData & |
me_data |
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Does the mode decision - Parameters:
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| my_buffer | the buffer of all the relevant frames |
| frame_num | the frame number for which motion estimation is being done |
| me_data | the motion vector data into which decisions will be written |
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float dirac::ModeDecider::DoUnitDecn |
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const int |
xpos, |
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const int |
ypos, |
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const int |
level |
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ValueType dirac::ModeDecider::GetDCPred |
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int |
xblock, |
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int |
yblock |
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float dirac::ModeDecider::GetDCVar |
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const ValueType |
dc_val, |
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const ValueType |
dc_pred |
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float dirac::ModeDecider::ModeCost |
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const int |
xindex, |
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const int |
yindex, |
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const PredMode |
predmode |
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Member Data Documentation
The documentation for this class was generated from the following file:
© 2004 British Broadcasting Corporation.
Dirac code licensed under the Mozilla Public License (MPL) Version 1.1.
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