xref: /aosp_15_r20/external/aac/libMpegTPEnc/src/tpenc_adts.cpp (revision e54365361535b070c2db7374cec45c159c7d0e7a)

/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android

© Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
Forschung e.V. All rights reserved.

 1.    INTRODUCTION
The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software
that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding
scheme for digital audio. This FDK AAC Codec software is intended to be used on
a wide variety of Android devices.

AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient
general perceptual audio codecs. AAC-ELD is considered the best-performing
full-bandwidth communications codec by independent studies and is widely
deployed. AAC has been standardized by ISO and IEC as part of the MPEG
specifications.

Patent licenses for necessary patent claims for the FDK AAC Codec (including
those of Fraunhofer) may be obtained through Via Licensing
(www.vialicensing.com) or through the respective patent owners individually for
the purpose of encoding or decoding bit streams in products that are compliant
with the ISO/IEC MPEG audio standards. Please note that most manufacturers of
Android devices already license these patent claims through Via Licensing or
directly from the patent owners, and therefore FDK AAC Codec software may
already be covered under those patent licenses when it is used for those
licensed purposes only.

Commercially-licensed AAC software libraries, including floating-point versions
with enhanced sound quality, are also available from Fraunhofer. Users are
encouraged to check the Fraunhofer website for additional applications
information and documentation.

2.    COPYRIGHT LICENSE

Redistribution and use in source and binary forms, with or without modification,
are permitted without payment of copyright license fees provided that you
satisfy the following conditions:

You must retain the complete text of this software license in redistributions of
the FDK AAC Codec or your modifications thereto in source code form.

You must retain the complete text of this software license in the documentation
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Fraunhofer provides no warranty of patent non-infringement with respect to this
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You may use this FDK AAC Codec software or modifications thereto only for
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This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright
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5.    CONTACT INFORMATION

Fraunhofer Institute for Integrated Circuits IIS
Attention: Audio and Multimedia Departments - FDK AAC LL
Am Wolfsmantel 33
91058 Erlangen, Germany

www.iis.fraunhofer.de/amm
[email protected]
----------------------------------------------------------------------------- */

/******************* MPEG transport format encoder library *********************

   Author(s):   Alex Groeschel

   Description: ADTS Transport Headers support

*******************************************************************************/

#include "tpenc_adts.h"

#include "tpenc_lib.h"
#include "tpenc_asc.h"

int adtsWrite_CrcStartReg(
    HANDLE_ADTS pAdts,        /*!< pointer to adts stucture */
    HANDLE_FDK_BITSTREAM hBs, /*!< handle to current bit buffer structure */
    int mBits                 /*!< number of bits in crc region */
) {
  if (pAdts->protection_absent) {
    return 0;
  }
  return (FDKcrcStartReg(&pAdts->crcInfo, hBs, mBits));
}

void adtsWrite_CrcEndReg(
    HANDLE_ADTS pAdts,        /*!< pointer to adts crc info stucture */
    HANDLE_FDK_BITSTREAM hBs, /*!< handle to current bit buffer structure */
    int reg                   /*!< crc region */
) {
  if (pAdts->protection_absent == 0) {
    FDKcrcEndReg(&pAdts->crcInfo, hBs, reg);
  }
}

int adtsWrite_GetHeaderBits(HANDLE_ADTS hAdts) {
  int bits = 0;

  if (hAdts->currentBlock == 0) {
    /* Static and variable header bits */
    bits = 56;
    if (!hAdts->protection_absent) {
      /* Add header/ single raw data block CRC bits */
      bits += 16;
      if (hAdts->num_raw_blocks > 0) {
        /* Add bits of raw data block position markers */
        bits += (hAdts->num_raw_blocks) * 16;
      }
    }
  }
  if (!hAdts->protection_absent && hAdts->num_raw_blocks > 0) {
    /* Add raw data block CRC bits. Not really part of the header, put they
     * cause bit overhead to be accounted. */
    bits += 16;
  }

  hAdts->headerBits = bits;

  return bits;
}

INT adtsWrite_Init(HANDLE_ADTS hAdts, CODER_CONFIG *config) {
  /* Sanity checks */
  if (config->nSubFrames < 1 || config->nSubFrames > 4 ||
      (int)config->aot > 4 || (int)config->aot < 1) {
    return -1;
  }

  /* fixed header */
  if (config->flags & CC_MPEG_ID) {
    hAdts->mpeg_id = 0; /* MPEG 4 */
  } else {
    hAdts->mpeg_id = 1; /* MPEG 2 */
  }
  hAdts->layer = 0;
  hAdts->protection_absent = !(config->flags & CC_PROTECTION);
  hAdts->profile = ((int)config->aot) - 1;
  hAdts->sample_freq_index = getSamplingRateIndex(config->samplingRate, 4);
  hAdts->sample_freq = config->samplingRate;
  hAdts->private_bit = 0;
  hAdts->channel_mode = config->channelMode;
  hAdts->original = 0;
  hAdts->home = 0;
  /* variable header */
  hAdts->copyright_id = 0;
  hAdts->copyright_start = 0;

  hAdts->num_raw_blocks = config->nSubFrames - 1; /* 0 means 1 raw data block */

  hAdts->channel_config_zero = config->channelConfigZero;

  FDKcrcInit(&hAdts->crcInfo, 0x8005, 0xFFFF, 16);

  hAdts->currentBlock = 0;

  return 0;
}

int adtsWrite_EncodeHeader(HANDLE_ADTS hAdts, HANDLE_FDK_BITSTREAM hBitStream,
                           int buffer_fullness, int frame_length) {
  INT crcIndex = 0;

  hAdts->headerBits = adtsWrite_GetHeaderBits(hAdts);

  FDK_ASSERT(((frame_length + hAdts->headerBits) / 8) < 0x2000); /*13 bit*/
  FDK_ASSERT(buffer_fullness < 0x800);                           /* 11 bit   */

  if (!hAdts->protection_absent) {
    FDKcrcReset(&hAdts->crcInfo);
  }

  if (hAdts->currentBlock == 0) {
    FDKresetBitbuffer(hBitStream, BS_WRITER);
  }

  hAdts->subFrameStartBit = FDKgetValidBits(hBitStream);

  /* Skip new header if this is raw data block 1..n */
  if (hAdts->currentBlock == 0) {
    FDKresetBitbuffer(hBitStream, BS_WRITER);

    if (hAdts->num_raw_blocks == 0) {
      crcIndex = adtsWrite_CrcStartReg(hAdts, hBitStream, 0);
    }

    /* fixed header */
    FDKwriteBits(hBitStream, 0xFFF, 12);
    FDKwriteBits(hBitStream, hAdts->mpeg_id, 1);
    FDKwriteBits(hBitStream, hAdts->layer, 2);
    FDKwriteBits(hBitStream, hAdts->protection_absent, 1);
    FDKwriteBits(hBitStream, hAdts->profile, 2);
    FDKwriteBits(hBitStream, hAdts->sample_freq_index, 4);
    FDKwriteBits(hBitStream, hAdts->private_bit, 1);
    FDKwriteBits(
        hBitStream,
        getChannelConfig(hAdts->channel_mode, hAdts->channel_config_zero), 3);
    FDKwriteBits(hBitStream, hAdts->original, 1);
    FDKwriteBits(hBitStream, hAdts->home, 1);
    /* variable header */
    FDKwriteBits(hBitStream, hAdts->copyright_id, 1);
    FDKwriteBits(hBitStream, hAdts->copyright_start, 1);
    FDKwriteBits(hBitStream, (frame_length + hAdts->headerBits) >> 3, 13);
    FDKwriteBits(hBitStream, buffer_fullness, 11);
    FDKwriteBits(hBitStream, hAdts->num_raw_blocks, 2);

    if (!hAdts->protection_absent) {
      int i;

      /* End header CRC portion for single raw data block and write dummy zero
       * values for unknown fields. */
      if (hAdts->num_raw_blocks == 0) {
        adtsWrite_CrcEndReg(hAdts, hBitStream, crcIndex);
      } else {
        for (i = 0; i < hAdts->num_raw_blocks; i++) {
          FDKwriteBits(hBitStream, 0, 16);
        }
      }
      FDKwriteBits(hBitStream, 0, 16);
    }
  } /* End of ADTS header */

  return 0;
}

void adtsWrite_EndRawDataBlock(HANDLE_ADTS hAdts, HANDLE_FDK_BITSTREAM hBs,
                               int *pBits) {
  if (!hAdts->protection_absent) {
    FDK_BITSTREAM bsWriter;

    FDKinitBitStream(&bsWriter, hBs->hBitBuf.Buffer, hBs->hBitBuf.bufSize, 0,
                     BS_WRITER);
    FDKpushFor(&bsWriter, 56);

    if (hAdts->num_raw_blocks == 0) {
      FDKwriteBits(&bsWriter, FDKcrcGetCRC(&hAdts->crcInfo), 16);
    } else {
      int distance;

      /* Write CRC of current raw data block */
      FDKwriteBits(hBs, FDKcrcGetCRC(&hAdts->crcInfo), 16);

      /* Write distance to current data block */
      if (hAdts->currentBlock < hAdts->num_raw_blocks) {
        FDKpushFor(&bsWriter, hAdts->currentBlock * 16);
        distance =
            FDKgetValidBits(hBs) - (56 + (hAdts->num_raw_blocks) * 16 + 16);
        FDKwriteBits(&bsWriter, distance >> 3, 16);
      }
    }
    FDKsyncCache(&bsWriter);
  }

  /* Write total frame lenth for multiple raw data blocks and header CRC */
  if (hAdts->num_raw_blocks > 0 &&
      hAdts->currentBlock == hAdts->num_raw_blocks) {
    FDK_BITSTREAM bsWriter;
    int crcIndex = 0;

    FDKinitBitStream(&bsWriter, hBs->hBitBuf.Buffer, hBs->hBitBuf.bufSize, 0,
                     BS_WRITER);

    if (!hAdts->protection_absent) {
      FDKcrcReset(&hAdts->crcInfo);
      crcIndex = FDKcrcStartReg(&hAdts->crcInfo, &bsWriter, 0);
    }
    /* Write total frame length */
    FDKpushFor(&bsWriter, 56 - 28 + 2);
    FDKwriteBits(&bsWriter, FDKgetValidBits(hBs) >> 3, 13);

    /* Write header CRC */
    if (!hAdts->protection_absent) {
      FDKpushFor(&bsWriter, 11 + 2 + (hAdts->num_raw_blocks) * 16);
      FDKcrcEndReg(&hAdts->crcInfo, &bsWriter, crcIndex);
      FDKwriteBits(&bsWriter, FDKcrcGetCRC(&hAdts->crcInfo), 16);
    }
    FDKsyncCache(&bsWriter);
  }

  /* Correct *pBits to reflect the amount of bits of the current subframe */
  *pBits -= hAdts->subFrameStartBit;
  if (!hAdts->protection_absent && hAdts->num_raw_blocks > 0) {
    /* Fixup CRC bits, since they come after each raw data block */
    *pBits += 16;
  }
  hAdts->currentBlock++;
}