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Diffstat (limited to 'media/libstagefright/codecs/mp3dec/src/pvmp3_seek_synch.cpp')
| -rw-r--r-- | media/libstagefright/codecs/mp3dec/src/pvmp3_seek_synch.cpp | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/mp3dec/src/pvmp3_seek_synch.cpp b/media/libstagefright/codecs/mp3dec/src/pvmp3_seek_synch.cpp new file mode 100644 index 0000000..82faafd --- /dev/null +++ b/media/libstagefright/codecs/mp3dec/src/pvmp3_seek_synch.cpp @@ -0,0 +1,308 @@ +/* ------------------------------------------------------------------ + * 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. + * ------------------------------------------------------------------- + */ +/* +------------------------------------------------------------------------------ + + PacketVideo Corp. + MP3 Decoder Library + + Filename: pvmp3_seek_synch.cpp + + Functions: + pvmp3_seek_synch + pvmp3_header_sync + + + Date: 9/21/2007 + +------------------------------------------------------------------------------ + REVISION HISTORY + + + Description: + +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + +pvmp3_frame_synch + +Input + pExt = pointer to the external interface structure. See the file + pvmp3decoder_api.h for a description of each field. + Data type of pointer to a tPVMP3DecoderExternal + structure. + + pMem = void pointer to hide the internal implementation of the library + It is cast back to a tmp3dec_file structure. This structure + contains information that needs to persist between calls to + this function, or is too big to be placed on the stack, even + though the data is only needed during execution of this function + Data type void pointer, internally pointer to a tmp3dec_file + structure. + + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + search mp3 sync word, when found, it verifies, based on header parameters, + the locations of the very next sync word, + - if fails, then indicates a false sync, + - otherwise, it confirm synchronization of at least 2 consecutives frames + +------------------------------------------------------------------------------ + REQUIREMENTS + + +------------------------------------------------------------------------------ + REFERENCES + +------------------------------------------------------------------------------ + PSEUDO-CODE + +------------------------------------------------------------------------------ +*/ + + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ + +#include "pvmp3_seek_synch.h" +#include "pvmp3_getbits.h" +#include "s_tmp3dec_file.h" +#include "pv_mp3dec_fxd_op.h" +#include "pvmp3_tables.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 +----------------------------------------------------------------------------*/ + + + +ERROR_CODE pvmp3_frame_synch(tPVMP3DecoderExternal *pExt, + void *pMem) /* bit stream structure */ +{ + uint16 val; + ERROR_CODE err; + + tmp3dec_file *pVars; + + pVars = (tmp3dec_file *)pMem; + + pVars->inputStream.pBuffer = pExt->pInputBuffer; + pVars->inputStream.usedBits = (pExt->inputBufferUsedLength << 3); // in bits + + + pVars->inputStream.inputBufferCurrentLength = (pExt->inputBufferCurrentLength); // in bits + + err = pvmp3_header_sync(&pVars->inputStream); + + if (err == NO_DECODING_ERROR) + { + /* validate synchronization by checking two consecutive sync words */ + + // to avoid multiple bitstream accesses + uint32 temp = getNbits(&pVars->inputStream, 21); + // put back whole header + pVars->inputStream.usedBits -= 21 + SYNC_WORD_LNGTH; + + int32 version; + + switch (temp >> 19) /* 2 */ + { + case 0: + version = MPEG_2_5; + break; + case 2: + version = MPEG_2; + break; + case 3: + version = MPEG_1; + break; + default: + version = INVALID_VERSION; + break; + } + + int32 freq_index = (temp << 20) >> 30; + + if (version != INVALID_VERSION && (freq_index != 3)) + { + int32 numBytes = fxp_mul32_Q28(mp3_bitrate[version][(temp<<16)>>28] << 20, + inv_sfreq[freq_index]); + + numBytes >>= (20 - version); + + if (version != MPEG_1) + { + numBytes >>= 1; + } + if ((temp << 22) >> 31) + { + numBytes++; + } + + if (numBytes > (int32)pVars->inputStream.inputBufferCurrentLength) + { + /* frame should account for padding and 2 bytes to check sync */ + pExt->CurrentFrameLength = numBytes + 3; + return (SYNCH_LOST_ERROR); + } + else if (numBytes == (int32)pVars->inputStream.inputBufferCurrentLength) + { + /* No enough data to validate, but current frame appears to be correct ( EOF case) */ + pExt->inputBufferUsedLength = pVars->inputStream.usedBits >> 3; + return (NO_DECODING_ERROR); + } + else + { + + int32 offset = pVars->inputStream.usedBits + ((numBytes) << 3); + + offset >>= INBUF_ARRAY_INDEX_SHIFT; + uint8 *pElem = pVars->inputStream.pBuffer + offset; + uint16 tmp1 = *(pElem++); + uint16 tmp2 = *(pElem); + + val = (tmp1 << 3); + val |= (tmp2 >> 5); + } + } + else + { + val = 0; // force mismatch + } + + if (val == SYNC_WORD) + { + pExt->inputBufferUsedLength = pVars->inputStream.usedBits >> 3; /// !!!!! + err = NO_DECODING_ERROR; + } + else + { + pExt->inputBufferCurrentLength = 0; + err = SYNCH_LOST_ERROR; + } + } + else + { + pExt->inputBufferCurrentLength = 0; + } + + return(err); + +} + +/* +------------------------------------------------------------------------------ + REVISION HISTORY + + + Description: + +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + +pvmp3_header_sync + +Input + tmp3Bits *inputStream, structure holding the input stream parameters + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + search mp3 sync word + +------------------------------------------------------------------------------ + REQUIREMENTS + + +------------------------------------------------------------------------------ + REFERENCES + +------------------------------------------------------------------------------ + PSEUDO-CODE + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ + + +ERROR_CODE pvmp3_header_sync(tmp3Bits *inputStream) +{ + uint16 val; + uint32 availableBits = (inputStream->inputBufferCurrentLength << 3); // in bits + + // byte aligment + inputStream->usedBits = (inputStream->usedBits + 7) & 8; + + val = (uint16)getUpTo17bits(inputStream, SYNC_WORD_LNGTH); + + while (((val&SYNC_WORD) != SYNC_WORD) && (inputStream->usedBits < availableBits)) + { + val <<= 8; + val |= getUpTo9bits(inputStream, 8); + } + + if ((val&SYNC_WORD) == SYNC_WORD && (inputStream->usedBits < availableBits)) + { + return(NO_DECODING_ERROR); + } + else + { + return(SYNCH_LOST_ERROR); + } + +} + |