diff options
Diffstat (limited to 'media/libstagefright/codecs/aacdec/lt_decode.cpp')
-rw-r--r-- | media/libstagefright/codecs/aacdec/lt_decode.cpp | 507 |
1 files changed, 507 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/aacdec/lt_decode.cpp b/media/libstagefright/codecs/aacdec/lt_decode.cpp new file mode 100644 index 0000000..e5f5f91 --- /dev/null +++ b/media/libstagefright/codecs/aacdec/lt_decode.cpp @@ -0,0 +1,507 @@ +/* ------------------------------------------------------------------ + * Copyright (C) 1998-2009 PacketVideo + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either + * express or implied. + * See the License for the specific language governing permissions + * and limitations under the License. + * ------------------------------------------------------------------- + */ +/* + + Pathname: lt_decode.c + + +------------------------------------------------------------------------------ + + REVISION HISTORY + + Description: Modified from original shareware code + + Description: Modified to pass variables by reference to eliminate use + of global variables. + + Description: First round of optimizations. + + Description: pInputStream is now the 2nd parameter to this function. + + Description: Changed to work with MT's new get_ics_info.c function, which + only calls lt_decode if LTP is enabled. This removes one grab from the + bitstream and one "if" from this code. Also, changed setting of weight. + Now, rather than setting the actual weight, I only set the index into + a table in this function. + + Description: Replace some instances of getbits to get9_n_lessbits + when the number of bits read is 9 or less and get1bits + when only 1 bit is read. + + Who: Date: + Description: +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + win_type Type of window (SHORT or LONG) + [WINDOW_TYPE] + + max_sfb Maximum number of active scalefactor bands + [Int] + + pLt_pred Pointer to structure containing information for + long-term prediction. + [LT_PRED_STATUS *] + + pInputStream Pointer to structure containing bitstream + information. + [BITS *] + + Local Stores/Buffers/Pointers Needed: + None + + Global Stores/Buffers/Pointers Needed: + None + + Outputs: + None + + Pointers and Buffers Modified: + pLt_pred->weight_index - updated with index into weight table for LTP. + + Local Stores Modified: + None + + Global Stores Modified: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function decodes the bitstream elements for long term prediction + +------------------------------------------------------------------------------ + REQUIREMENTS + + +------------------------------------------------------------------------------ + REFERENCES + + (1) MPEG-2 NBC Audio Decoder + "This software module was originally developed by Nokia + in the course of development of the MPEG-2 AAC/MPEG-4 Audio standard + ISO/IEC13818-7, 14496-1, 2 and 3. This software module is an implementation + of a part of one or more MPEG-2 AAC/MPEG-4 Audio tools as specified by the + MPEG-2 aac/MPEG-4 Audio standard. ISO/IEC gives users of the + MPEG-2aac/MPEG-4 Audio standards free license to this software module or + modifications thereof for use in hardware or software products claiming + conformance to the MPEG-2 aac/MPEG-4 Audio standards. Those intending to + use this software module in hardware or software products are advised that + this use may infringe existing patents. The original developer of this + software module, the subsequent editors and their companies, and ISO/IEC + have no liability for use of this software module or modifications thereof + in an implementation. Copyright is not released for non MPEG-2 aac/MPEG-4 + Audio conforming products. The original developer retains full right to use + the code for the developer's own purpose, assign or donate the code to a + third party and to inhibit third party from using the code for non + MPEG-2 aac/MPEG-4 Audio conforming products. This copyright notice + must be included in all copies or derivative works." + Copyright (c)1997. + +------------------------------------------------------------------------------ + PSEUDO-CODE + + pDelay[0] = (Int) getbits( + LEN_LTP_LAG, + pInputStream); + + temp_reg = (Int) getbits( + LEN_LTP_COEF, + pInputStream); + + pLt_pred->weight = codebook[temp_reg]; + + last_band = max_sfb; + + IF (win_type != EIGHT_SHORT_SEQUENCE) + + IF (last_band > MAX_LT_PRED_LONG_SFB) + + last_band = MAX_LT_PRED_LONG_SFB; + + ENDIF + + FOR (m = last_band; m > 0; m--) + + *(pSfbPredictionUsed++) = (Int) getbits( + LEN_LTP_LONG_USED, + pInputStream); + ENDFOR + + FOR (m = (max_sfb - last_band); m > 0; m--) + + *(pSfbPredictionUsed++) = 0; + + ENDFOR + + ELSE + + IF (last_band > MAX_LT_PRED_SHORT_SFB) + + last_band = MAX_LT_PRED_SHORT_SFB; + + ENDIF + + prev_subblock = pDelay[0]; + + pWinPredictionUsed++; + + pTempPtr = &pSfbPredictionUsed[0]; + + FOR (m = NUM_SHORT_WINDOWS; m > 0;) + + m--; + temp_reg = (Int) getbits( + LEN_LTP_SHORT_USED, + pInputStream); + + *(pWinPredictionUsed++) = temp_reg; + + IF (temp_reg != FALSE) + { + *(pDelay++) = prev_subblock; + + FOR (k = last_band; k > 0; k--) + { + *(pTempPtr++) = 1; + } + break; + ELSE + { + pDelay++; + pTempPtr += last_band; + } + + ENDFOR (m = NUM_SHORT_WINDOWS; m > 0;) + + prev_subblock += LTP_LAG_OFFSET; + + FOR (; m > 0; m--) + + temp_reg = (Int) getbits ( + LEN_LTP_SHORT_USED, + pInputStream); + + *(pWinPredictionUsed++) = temp_reg; + + IF (temp_reg != FALSE) + + temp_reg = (Int) getbits( + LEN_LTP_SHORT_LAG_PRESENT, + pInputStream); + IF (temp_reg != 0) + + temp_reg = (Int) getbits( + LEN_LTP_SHORT_LAG, + pInputStream); + + *(pDelay++) = prev_subblock - temp_reg; + + ELSE + + *(pDelay++) = prev_subblock - LTP_LAG_OFFSET; + + ENDIF + + FOR (k = last_band; k > 0; k--) + *(pTempPtr++) = 1; + ENDFOR + + ELSE + + pDelay++; + pTempPtr += last_band; + + ENDIF + + ENDFOR (; m > 0; m--) + + ENDIF (win_type != EIGHT_SHORT_SEQUENCE) + +------------------------------------------------------------------------------ + RESOURCES USED + When the code is written for a specific target processor the + the resources used should be documented below. + + STACK USAGE: [stack count for this module] + [variable to represent + stack usage for each subroutine called] + + where: [stack usage variable] = stack usage for [subroutine + name] (see [filename].ext) + + DATA MEMORY USED: x words + + PROGRAM MEMORY USED: x words + + CLOCK CYCLES: [cycle count equation for this module] + [variable + used to represent cycle count for each subroutine + called] + + where: [cycle count variable] = cycle count for [subroutine + name] (see [filename].ext) + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ +#include "pv_audio_type_defs.h" +#include "lt_decode.h" +#include "ltp_common_internal.h" +#include "window_block_fxp.h" +#include "e_window_sequence.h" +#include "s_lt_pred_status.h" +#include "s_bits.h" +#include "ibstream.h" + +/*---------------------------------------------------------------------------- +; MACROS +; Define module specific macros here +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; DEFINES +; Include all pre-processor statements here. Include conditional +; compile variables also. +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL FUNCTION DEFINITIONS +; Function Prototype declaration +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL STORE/BUFFER/POINTER DEFINITIONS +; Variable declaration - defined here and used outside this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL FUNCTION REFERENCES +; Declare functions defined elsewhere and referenced in this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES +; Declare variables used in this module but defined elsewhere +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ +void lt_decode( + const WINDOW_SEQUENCE win_type, + BITS *pInputStream, + const Int max_sfb, + LT_PRED_STATUS *pLt_pred) +{ + Int wnd_num; + Int k; + Int last_band; + Int prev_subblock; + Int prev_subblock_nonzero; + Int temp_reg; + + Bool *pWinPredictionUsed = pLt_pred->win_prediction_used; + Bool *pSfbPredictionUsed = pLt_pred->sfb_prediction_used; + Int *pTempPtr; + Int *pDelay = pLt_pred->delay; + + pDelay[0] = (Int) get17_n_lessbits( + LEN_LTP_LAG, /* 11 bits */ + pInputStream); + + pLt_pred->weight_index = (Int) get9_n_lessbits( + LEN_LTP_COEF, /* 3 bits */ + pInputStream); + + last_band = max_sfb; + + if (win_type != EIGHT_SHORT_SEQUENCE) + { + + /* last_band = min(MAX_LT_PRED_LONG_SFB, max_sfb) MAX_SCFAC_BANDS */ + if (last_band > MAX_LT_PRED_LONG_SFB) + { + last_band = MAX_LT_PRED_LONG_SFB; + } + + for (k = last_band; k > 0; k--) + { + *(pSfbPredictionUsed++) = (Int) get1bits(pInputStream); + } + + /* + * This is not a call to memset, because + * (max_sfb - last_band) should typically be a small value. + */ + for (k = (max_sfb - last_band); k > 0; k--) + { + *(pSfbPredictionUsed++) = FALSE; + } + } + else /* (win_type == EIGHT_SHORT_SEQUENCE) */ + { + /* last_band = min(MAX_LT_PRED_SHORT_SFB, max_sfb) */ + + if (last_band > MAX_LT_PRED_SHORT_SFB) + { + last_band = MAX_LT_PRED_SHORT_SFB; + } + + /* + * The following two coding constructs are equivalent... + * + * first_time == 1 + * for (wnd_num=NUM_SHORT_WINDOWS; wnd_num > 0; wnd_num--) + * { + * if (condition) + * { + * if (first_time == 1) + * { + * CODE SECTION A + * first_time = 0; + * } + * else + * { + * CODE SECTION B + * } + * } + * } + * + * -----------------------------------EQUIVALENT TO------------ + * + * wnd_num=NUM_SHORT_WINDOWS; + * + * do + * { + * wnd_num--; + * if (condition) + * { + * CODE SECTION A + * break; + * } + * } while( wnd_num > 0) + * + * while (wnd_num > 0) + * { + * if (condition) + * { + * CODE SECTION B + * } + * wnd_num--; + * } + * + */ + + prev_subblock = pDelay[0]; + + pTempPtr = &pSfbPredictionUsed[0]; + + wnd_num = NUM_SHORT_WINDOWS; + + prev_subblock_nonzero = prev_subblock; + prev_subblock += LTP_LAG_OFFSET; + + do + { + /* + * Place decrement of wnd_num here, to insure + * that the decrement occurs before the + * break out of the do-while loop. + */ + wnd_num--; + + temp_reg = (Int) get1bits(pInputStream); + + *(pWinPredictionUsed++) = temp_reg; + + if (temp_reg != FALSE) + { + *(pDelay++) = prev_subblock_nonzero; + + for (k = last_band; k > 0; k--) + { + *(pTempPtr++) = TRUE; + } + for (k = (max_sfb - last_band); k > 0; k--) + { + *(pTempPtr++) = FALSE; + } + break; + + } /* if(pWinPredictionUsed) */ + else + { + pDelay++; + pTempPtr += max_sfb; + } + + } + while (wnd_num > 0); + + /* + * This while loop picks up where the previous one left off. + * Notice that the code functions differently inside the loop + */ + + while (wnd_num > 0) + { + temp_reg = (Int) get1bits(pInputStream); + + *(pWinPredictionUsed++) = temp_reg; + + if (temp_reg != FALSE) + { + temp_reg = (Int) get1bits(pInputStream); + if (temp_reg != 0) + { + temp_reg = (Int) get9_n_lessbits( + LEN_LTP_SHORT_LAG, + pInputStream); + + *(pDelay++) = prev_subblock - temp_reg; + } + else + { + *(pDelay++) = prev_subblock_nonzero; + } + for (k = last_band; k > 0; k--) + { + *(pTempPtr++) = TRUE; + } + for (k = (max_sfb - last_band); k > 0; k--) + { + *(pTempPtr++) = FALSE; + } + + } /* if (temp_reg) */ + else + { + pDelay++; + pTempPtr += max_sfb; + } + + wnd_num--; + + } /* while(wnd_num) */ + + } /* else (win_type == EIGHT_SHORT_SEQUENCE) */ + +} /* lt_decode */ |