decoder/srce/decoder-sbc.c

/******************************************************************************
 *
 *  Copyright (C) 2014 The Android Open Source Project
 *  Copyright 2006 Open Interface North America, Inc. All rights reserved.
 *
 *  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.
 *
 ******************************************************************************/

/*******************************************************************************
  $Revision: #1 $
 ******************************************************************************/

/** @file
@ingroup codec_internal
*/

/**@addtogroup codec_internal */
/**@{*/

#include "oi_bitstream.h"
#include "oi_codec_sbc_private.h"

#define SPECIALIZE_READ_SAMPLES_JOINT

/**
 * Scans through a buffer looking for a codec syncword. If the decoder has been
 * set for enhanced operation using OI_CODEC_SBC_DecoderReset(), it will search
 * for both a standard and an enhanced syncword.
 */
PRIVATE OI_STATUS FindSyncword(OI_CODEC_SBC_DECODER_CONTEXT* context,
                               const OI_BYTE** frameData,
                               uint32_t* frameBytes) {
#ifdef SBC_ENHANCED
  OI_BYTE search1 = OI_SBC_SYNCWORD;
  OI_BYTE search2 = OI_SBC_ENHANCED_SYNCWORD;
#endif  // SBC_ENHANCED

  if (*frameBytes == 0) {
    return OI_CODEC_SBC_NOT_ENOUGH_HEADER_DATA;
  }

#ifdef SBC_ENHANCED
  if (context->limitFrameFormat && context->enhancedEnabled) {
    /* If the context is restricted, only search for specified SYNCWORD */
    search1 = search2;
  } else if (context->enhancedEnabled == FALSE) {
    /* If enhanced is not enabled, only search for classic SBC SYNCWORD*/
    search2 = search1;
  }
  while (*frameBytes && (**frameData != search1) && (**frameData != search2)) {
    (*frameBytes)--;
    (*frameData)++;
  }
  if (*frameBytes) {
    /* Syncword found, *frameData points to it, and *frameBytes correctly
     * reflects the number of bytes available to read, including the
     * syncword. */
    context->common.frameInfo.enhanced =
        (**frameData == OI_SBC_ENHANCED_SYNCWORD);
    return OI_OK;
  } else {
    /* No syncword was found anywhere in the provided input data.
     * *frameData points past the end of the original input, and
     * *frameBytes is 0. */
    return OI_CODEC_SBC_NO_SYNCWORD;
  }
#else   // SBC_ENHANCED
  while (*frameBytes && (**frameData != OI_SBC_SYNCWORD)) {
    (*frameBytes)--;
    (*frameData)++;
  }
  if (*frameBytes) {
    /* Syncword found, *frameData points to it, and *frameBytes correctly
     * reflects the number of bytes available to read, including the
     * syncword. */
    context->common.frameInfo.enhanced = FALSE;
    return OI_OK;
  } else {
    /* No syncword was found anywhere in the provided input data.
     * *frameData points past the end of the original input, and
     * *frameBytes is 0. */
    return OI_CODEC_SBC_NO_SYNCWORD;
  }
#endif  // SBC_ENHANCED
}

static OI_STATUS DecodeBody(OI_CODEC_SBC_DECODER_CONTEXT* context,
                            const OI_BYTE* bodyData, int16_t* pcmData,
                            uint32_t* pcmBytes, OI_BOOL allowPartial) {
  OI_BITSTREAM bs;
  OI_UINT frameSamples = context->common.frameInfo.nrof_blocks *
                         context->common.frameInfo.nrof_subbands;
  OI_UINT decode_block_count;

  /*
   * Based on the header data, make sure that there is enough room to write the
   * output samples.
   */
  if (*pcmBytes <
          (sizeof(int16_t) * frameSamples * context->common.pcmStride) &&
      !allowPartial) {
    /* If we're not allowing partial decodes, we need room for the entire
     * codec frame */
    TRACE(("-OI_CODEC_SBC_Decode: OI_CODEC_SBC_NOT_ENOUGH_AUDIO_DATA"));
    return OI_CODEC_SBC_NOT_ENOUGH_AUDIO_DATA;
  } else if (*pcmBytes < sizeof(int16_t) *
                             context->common.frameInfo.nrof_subbands *
                             context->common.pcmStride) {
    /* Even if we're allowing partials, we can still only decode on a frame
     * boundary */
    return OI_CODEC_SBC_NOT_ENOUGH_AUDIO_DATA;
  }

  if (context->bufferedBlocks == 0) {
    TRACE(("Reading scalefactors"));
    OI_SBC_ReadScalefactors(&context->common, bodyData, &bs);

    TRACE(("Computing bit allocation"));
    OI_SBC_ComputeBitAllocation(&context->common);

    TRACE(("Reading samples"));
    if (context->common.frameInfo.mode == SBC_JOINT_STEREO) {
      OI_SBC_ReadSamplesJoint(context, &bs);
    } else {
      OI_SBC_ReadSamples(context, &bs);
    }

    context->bufferedBlocks = context->common.frameInfo.nrof_blocks;
  }

  if (allowPartial) {
    decode_block_count = *pcmBytes / sizeof(int16_t) /
                         context->common.pcmStride /
                         context->common.frameInfo.nrof_subbands;

    if (decode_block_count > context->bufferedBlocks) {
      decode_block_count = context->bufferedBlocks;
    }

  } else {
    decode_block_count = context->common.frameInfo.nrof_blocks;
  }

  TRACE(("Synthesizing frame"));
  {
    OI_UINT start_block =
        context->common.frameInfo.nrof_blocks - context->bufferedBlocks;
    OI_SBC_SynthFrame(context, pcmData, start_block, decode_block_count);
  }

  OI_ASSERT(context->bufferedBlocks >= decode_block_count);
  context->bufferedBlocks -= decode_block_count;

  frameSamples = decode_block_count * context->common.frameInfo.nrof_subbands;

  /*
   * When decoding mono into a stride-2 array, copy pcm data to second channel
   */
  if (context->common.frameInfo.nrof_channels == 1 &&
      context->common.pcmStride == 2) {
    OI_UINT i;
    for (i = 0; i < frameSamples; ++i) {
      pcmData[2 * i + 1] = pcmData[2 * i];
    }
  }

  /*
   * Return number of pcm bytes generated by the decode operation.
   */
  *pcmBytes = frameSamples * sizeof(int16_t) * context->common.pcmStride;
  if (context->bufferedBlocks > 0) {
    return OI_CODEC_SBC_PARTIAL_DECODE;
  } else {
    return OI_OK;
  }
}

PRIVATE OI_STATUS internal_DecodeRaw(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                     uint8_t bitpool, const OI_BYTE** frameData,
                                     uint32_t* frameBytes, int16_t* pcmData,
                                     uint32_t* pcmBytes) {
  OI_STATUS status;
  OI_UINT bodyLen;

  TRACE(("+OI_CODEC_SBC_DecodeRaw"));

  if (context->bufferedBlocks == 0) {
    /*
     * The bitallocator needs to know the bitpool value.
     */
    context->common.frameInfo.bitpool = bitpool;
    /*
     * Compute the frame length and check we have enough frame data to proceed
     */
    bodyLen = OI_CODEC_SBC_CalculateFramelen(&context->common.frameInfo) -
              SBC_HEADER_LEN;
    if (*frameBytes < bodyLen) {
      TRACE(("-OI_CODEC_SBC_Decode: OI_CODEC_SBC_NOT_ENOUGH_BODY_DATA"));
      return OI_CODEC_SBC_NOT_ENOUGH_BODY_DATA;
    }
  } else {
    bodyLen = 0;
  }
  /*
   * Decode the SBC data. Pass TRUE to DecodeBody to allow partial decoding of
   * tones.
   */
  status = DecodeBody(context, *frameData, pcmData, pcmBytes, TRUE);
  if (OI_SUCCESS(status) || status == OI_CODEC_SBC_PARTIAL_DECODE) {
    *frameData += bodyLen;
    *frameBytes -= bodyLen;
  }
  TRACE(("-OI_CODEC_SBC_DecodeRaw: %d", status));
  return status;
}

OI_STATUS OI_CODEC_SBC_DecoderReset(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                    uint32_t* decoderData,
                                    uint32_t decoderDataBytes,
                                    uint8_t maxChannels, uint8_t pcmStride,
                                    OI_BOOL enhanced) {
  return internal_DecoderReset(context, decoderData, decoderDataBytes,
                               maxChannels, pcmStride, enhanced);
}

OI_STATUS OI_CODEC_SBC_DecodeFrame(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                   const OI_BYTE** frameData,
                                   uint32_t* frameBytes, int16_t* pcmData,
                                   uint32_t* pcmBytes) {
  OI_STATUS status;
  OI_UINT framelen;
  uint8_t crc;

  TRACE(("+OI_CODEC_SBC_DecodeFrame"));

  TRACE(("Finding syncword"));
  status = FindSyncword(context, frameData, frameBytes);
  if (!OI_SUCCESS(status)) {
    return status;
  }

  /* Make sure enough data remains to read the header. */
  if (*frameBytes < SBC_HEADER_LEN) {
    TRACE(("-OI_CODEC_SBC_DecodeFrame: OI_CODEC_SBC_NOT_ENOUGH_HEADER_DATA"));
    return OI_CODEC_SBC_NOT_ENOUGH_HEADER_DATA;
  }

  TRACE(("Reading Header"));
  OI_SBC_ReadHeader(&context->common, *frameData);

  /*
   * Some implementations load the decoder into RAM and use overlays for 4 vs 8
   * subbands. We need
   * to ensure that the SBC parameters for this frame are compatible with the
   * restrictions imposed
   * by the loaded overlays.
   */
  if (context->limitFrameFormat &&
      (context->common.frameInfo.subbands != context->restrictSubbands)) {
    ERROR(("SBC parameters incompatible with loaded overlay"));
    return OI_STATUS_INVALID_PARAMETERS;
  }

  if (context->common.frameInfo.nrof_channels > context->common.maxChannels) {
    ERROR(
        ("SBC parameters incompatible with number of channels specified during "
         "reset"));
    return OI_STATUS_INVALID_PARAMETERS;
  }

  if (context->common.pcmStride < 1 || context->common.pcmStride > 2) {
    ERROR(("PCM stride not set correctly during reset"));
    return OI_STATUS_INVALID_PARAMETERS;
  }

  /*
   * At this point a header has been read. However, it's possible that we found
   * a false syncword,
   * so the header data might be invalid. Make sure we have enough bytes to read
   * in the
   * CRC-protected header, but don't require we have the whole frame. That way,
   * if it turns out
   * that we're acting on bogus header data, we don't stall the decoding process
   * by waiting for
   * data that we don't actually need.
   */
  framelen = OI_CODEC_SBC_CalculateFramelen(&context->common.frameInfo);
  if (*frameBytes < framelen) {
    TRACE(("-OI_CODEC_SBC_DecodeFrame: OI_CODEC_SBC_NOT_ENOUGH_BODY_DATA"));
    return OI_CODEC_SBC_NOT_ENOUGH_BODY_DATA;
  }

  TRACE(("Calculating checksum"));

  crc = OI_SBC_CalculateChecksum(&context->common.frameInfo, *frameData);
  if (crc != context->common.frameInfo.crc) {
    TRACE(("CRC Mismatch:  calc=%02x read=%02x\n", crc,
           context->common.frameInfo.crc));
    TRACE(("-OI_CODEC_SBC_DecodeFrame: OI_CODEC_SBC_CHECKSUM_MISMATCH"));
    return OI_CODEC_SBC_CHECKSUM_MISMATCH;
  }

#ifdef OI_DEBUG
  /*
   * Make sure the bitpool values are sane.
   */
  if ((context->common.frameInfo.bitpool < SBC_MIN_BITPOOL) &&
      !context->common.frameInfo.enhanced) {
    ERROR(("Bitpool too small: %d (must be >= 2)",
           context->common.frameInfo.bitpool));
    return OI_STATUS_INVALID_PARAMETERS;
  }
  if (context->common.frameInfo.bitpool >
      OI_SBC_MaxBitpool(&context->common.frameInfo)) {
    ERROR(("Bitpool too large: %d (must be <= %ld)",
           context->common.frameInfo.bitpool,
           OI_SBC_MaxBitpool(&context->common.frameInfo)));
    return OI_STATUS_INVALID_PARAMETERS;
  }
#endif

  /*
   * Now decode the SBC data. Partial decode is not yet implemented for an SBC
   * stream, so pass FALSE to decode body to have it enforce the old rule that
   * you have to decode a whole packet at a time.
   */
  status = DecodeBody(context, *frameData + SBC_HEADER_LEN, pcmData, pcmBytes,
                      FALSE);
  if (OI_SUCCESS(status)) {
    *frameData += framelen;
    *frameBytes -= framelen;
  }
  TRACE(("-OI_CODEC_SBC_DecodeFrame: %d", status));

  return status;
}

OI_STATUS OI_CODEC_SBC_SkipFrame(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                 const OI_BYTE** frameData,
                                 uint32_t* frameBytes) {
  OI_STATUS status;
  OI_UINT framelen;
  OI_UINT headerlen;
  uint8_t crc;

  status = FindSyncword(context, frameData, frameBytes);
  if (!OI_SUCCESS(status)) {
    return status;
  }
  if (*frameBytes < SBC_HEADER_LEN) {
    return OI_CODEC_SBC_NOT_ENOUGH_HEADER_DATA;
  }
  OI_SBC_ReadHeader(&context->common, *frameData);
  framelen =
      OI_SBC_CalculateFrameAndHeaderlen(&context->common.frameInfo, &headerlen);
  if (*frameBytes < headerlen) {
    return OI_CODEC_SBC_NOT_ENOUGH_HEADER_DATA;
  }
  crc = OI_SBC_CalculateChecksum(&context->common.frameInfo, *frameData);
  if (crc != context->common.frameInfo.crc) {
    return OI_CODEC_SBC_CHECKSUM_MISMATCH;
  }
  if (*frameBytes < framelen) {
    return OI_CODEC_SBC_NOT_ENOUGH_BODY_DATA;
  }
  context->bufferedBlocks = 0;
  *frameData += framelen;
  *frameBytes -= framelen;
  return OI_OK;
}

uint8_t OI_CODEC_SBC_FrameCount(OI_BYTE* frameData, uint32_t frameBytes) {
  uint8_t mode;
  uint8_t blocks;
  uint8_t subbands;
  uint8_t frameCount = 0;
  OI_UINT frameLen;

  while (frameBytes) {
    while (frameBytes && ((frameData[0] & 0xFE) != 0x9C)) {
      frameData++;
      frameBytes--;
    }

    if (frameBytes < SBC_HEADER_LEN) {
      return frameCount;
    }

    /* Extract and translate required fields from Header */
    subbands = mode = blocks = frameData[1];
    ;
    mode = (mode & (BIT3 | BIT2)) >> 2;
    blocks = block_values[(blocks & (BIT5 | BIT4)) >> 4];
    subbands = band_values[(subbands & BIT0)];

    /* Inline logic to avoid corrupting context */
    frameLen = blocks * frameData[2];
    switch (mode) {
      case SBC_JOINT_STEREO:
        frameLen += subbands + (8 * subbands);
        break;

      case SBC_DUAL_CHANNEL:
        frameLen *= 2;
      /* fall through */

      default:
        if (mode == SBC_MONO) {
          frameLen += 4 * subbands;
        } else {
          frameLen += 8 * subbands;
        }
    }

    frameCount++;
    frameLen = SBC_HEADER_LEN + (frameLen + 7) / 8;
    if (frameBytes > frameLen) {
      frameBytes -= frameLen;
      frameData += frameLen;
    } else {
      frameBytes = 0;
    }
  }
  return frameCount;
}

/** Read quantized subband samples from the input bitstream and expand them. */

#ifdef SPECIALIZE_READ_SAMPLES_JOINT

PRIVATE void OI_SBC_ReadSamplesJoint4(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                      OI_BITSTREAM* global_bs) {
#define NROF_SUBBANDS 4
#include "readsamplesjoint.inc"
#undef NROF_SUBBANDS
}

PRIVATE void OI_SBC_ReadSamplesJoint8(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                      OI_BITSTREAM* global_bs) {
#define NROF_SUBBANDS 8
#include "readsamplesjoint.inc"
#undef NROF_SUBBANDS
}

typedef void (*READ_SAMPLES)(OI_CODEC_SBC_DECODER_CONTEXT* context,
                             OI_BITSTREAM* global_bs);

static const READ_SAMPLES SpecializedReadSamples[] = {OI_SBC_ReadSamplesJoint4,
                                                      OI_SBC_ReadSamplesJoint8};

#endif /* SPECIALIZE_READ_SAMPLES_JOINT */

PRIVATE void OI_SBC_ReadSamplesJoint(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                     OI_BITSTREAM* global_bs) {
  OI_CODEC_SBC_COMMON_CONTEXT* common = &context->common;
  OI_UINT nrof_subbands = common->frameInfo.nrof_subbands;
#ifdef SPECIALIZE_READ_SAMPLES_JOINT
  OI_ASSERT((nrof_subbands >> 3u) <= 1u);
  SpecializedReadSamples[nrof_subbands >> 3](context, global_bs);
#else

#define NROF_SUBBANDS nrof_subbands
#include "readsamplesjoint.inc"
#undef NROF_SUBBANDS
#endif /* SPECIALIZE_READ_SAMPLES_JOINT */
}

/**@}*/