H.264 reference frame List Management Analysis -- Analysis of related functions in JM (lower)

This article analyzes several functions related to the image marking process.

[Cpp]
/*!
**************************************** ********************************
* \ Brief
* Perform Sliding window decoded reference picture marking process refer to the Sliding window marking process of the image
*
**************************************** ********************************
*/
Static void sliding_window_memory_management (StorablePicture * p)
{
Unsigned I;
 
Assert (! P-> idr_flag );
// If this is a reference pic with sliding window, unmark first ref frame
If (dpb. ref_frames_in_buffer = dpb. num_ref_frames-dpb. ltref_frames_in_buffer )//! <Less dpb. ltref_frames_in_buffer cannot be used on long-term reference frames due to Sliding Window labels
{
For (I = 0; I <dpb. used_size; I ++ )//! <Adopt a FIFO policy to remove the first short-term reference frame from the reference frame list in dpb and update the reference frame list.
{
If (dpb. fs [I]-> is_reference &&(! (Dpb. fs [I]-> is_long_term )))
{
Unmark_for_reference (dpb. fs [I]); //! <Mark this frame as a non-Reference Frame
Update_ref_list ();//! <Update the reference frame list
Break;
}
}
}
 
P-> is_long_term = 0;
}

 

[Cpp]
<Span style = "font-size: 12px;"> /*!
**************************************** ********************************
* \ Brief
* Perform Adaptive memory control decoded reference picture marking process Adaptive marking process
**************************************** ********************************
*/
Static void adaptive_memory_management (StorablePicture * p)
{
DecRefPicMarking_t * tmp_drpm;

Img-> last_has_mmco_5 = 0 ;//! <Memory_management_control_operation
 
Assert (! P-> idr_flag );
Assert (p-> adaptive_ref_pic_buffering_flag );
 
While (p-> dec_ref_pic_marking_buffer )//! <Stores the memory management control operations
{
Tmp_drpm = p-> dec_ref_pic_marking_buffer ;//! <Temporary save operation, which can be used to release the corresponding memory after the operation is completed
Switch (tmp_drpm-> memory_management_control_operation)
{
Case 0 ://! <End loop: exit the tag operation.
If (tmp_drpm-> Next! = NULL)
{
Error ("memory_management_control_operation = 0 not last operation in buffer", 500 );
}
Break;
Case 1 ://! <Mark a short-term reference image as a non-Reference Image
Mm_unmark_short_term_for_reference (p, tmp_drpm-> difference_of_pic_nums_minus1 );
Update_ref_list ();
Break;
Case 2 ://! <Mark a long-term reference image as a non-Reference Image
Mm_unmark_long_term_for_reference (p, tmp_drpm-> long_term_pic_num );
Update_ltref_list ();
Break;
Case 3 ://! <Convert a short-term reference image to a long-term reference image
Mm_assign_long_term_frame_idx (p, tmp_drpm-> difference_of_pic_nums_minus1, tmp_drpm-> long_term_frame_idx );
Update_ref_list ();
Update_ltref_list ();
Break;
Case 4 ://! <Specify the maximum number of long-term reference frames
Mm_update_max_long_term_frame_idx (tmp_drpm-> max_long_term_frame_idx_plus1 );
Update_ltref_list ();
Break;
Case 5 ://! <Clear the reference frame queue, remove all reference images from the reference frame queue, and disable the long-term reference mechanism.
Mm_unmark_all_short_term_for_reference ();
Mm_unmark_all_long_term_for_reference ();
Img-> last_has_mmco_5 = 1 ;//! <Mark here for the next POC update
Break;
Case 6 ://! <Save the current image as a long-term reference frame
Mm_mark_current_picture_long_term (p, tmp_drpm-> long_term_frame_idx );
Check_num_ref ();
Break;
Default:
Error ("invalid memory_management_control_operation in buffer", 500 );
}
P-> dec_ref_pic_marking_buffer = tmp_drpm-> Next ;//! <Take the next operation
Free (tmp_drpm );//! <Release the memory of the completed operation
}
If (img-> last_has_mmco_5)
{
P-> pic_num = p-> frame_num = 0 ;//! <Frame_num is cleared because the reference frame list is cleared.

Switch (p-> structure)
{
Case TOP_FIELD:
{
P-> poc = p-> top_poc = img-> toppoc = 0;
Break;
}
Case BOTTOM_FIELD:
{
P-> poc = p-> bottom_poc = img-> bottompoc = 0;
Break;
}
Case FRAME ://! <Frame mode
{Www.2cto.com
P-> top_poc-= p-> poc;
P-> bottom_poc-= p-> poc;
 
Img-> toppoc = p-> top_poc;
Img-> bottompoc = p-> bottom_poc;
 
P-> poc = min (p-> top_poc, p-> bottom_poc );
Img-> framepoc = p-> poc;
Break;
}
}
Img-> ThisPOC = p-> poc;
Flush_dpb ();
}
} </Span>