diff options
Diffstat (limited to 'libavcodec/sbc.c')
-rw-r--r-- | libavcodec/sbc.c | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/libavcodec/sbc.c b/libavcodec/sbc.c new file mode 100644 index 0000000..f7dba79 --- /dev/null +++ b/libavcodec/sbc.c @@ -0,0 +1,271 @@ +/* + * Bluetooth low-complexity, subband codec (SBC) + * + * Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org> + * Copyright (C) 2012-2013 Intel Corporation + * Copyright (C) 2008-2010 Nokia Corporation + * Copyright (C) 2004-2010 Marcel Holtmann <marcel@holtmann.org> + * Copyright (C) 2004-2005 Henryk Ploetz <henryk@ploetzli.ch> + * Copyright (C) 2005-2008 Brad Midgley <bmidgley@xmission.com> + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * SBC common functions for the encoder and decoder + */ + +#include "avcodec.h" +#include "sbc.h" + +/* A2DP specification: Appendix B, page 69 */ +static const int sbc_offset4[4][4] = { + { -1, 0, 0, 0 }, + { -2, 0, 0, 1 }, + { -2, 0, 0, 1 }, + { -2, 0, 0, 1 } +}; + +/* A2DP specification: Appendix B, page 69 */ +static const int sbc_offset8[4][8] = { + { -2, 0, 0, 0, 0, 0, 0, 1 }, + { -3, 0, 0, 0, 0, 0, 1, 2 }, + { -4, 0, 0, 0, 0, 0, 1, 2 }, + { -4, 0, 0, 0, 0, 0, 1, 2 } +}; + +/* + * Calculates the CRC-8 of the first len bits in data + */ +uint8_t sbc_crc8(const AVCRC *ctx, const uint8_t *data, size_t len) +{ + size_t byte_length = len >> 3; + int bit_length = len & 7; + uint8_t crc; + + crc = av_crc(ctx, 0x0F, data, byte_length); + + if (bit_length) { + uint8_t bits = data[byte_length]; + while (bit_length--) { + int8_t mask = bits ^ crc; + crc = (crc << 1) ^ ((mask >> 7) & 0x1D); + bits <<= 1; + } + } + + return crc; +} + +/* + * Code straight from the spec to calculate the bits array + * Takes a pointer to the frame in question and a pointer to the bits array + */ +void ff_sbc_calculate_bits(const struct sbc_frame *frame, int (*bits)[8]) +{ + int subbands = frame->subbands; + uint8_t sf = frame->frequency; + + if (frame->mode == MONO || frame->mode == DUAL_CHANNEL) { + int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice; + int ch, sb; + + for (ch = 0; ch < frame->channels; ch++) { + max_bitneed = 0; + if (frame->allocation == SNR) { + for (sb = 0; sb < subbands; sb++) { + bitneed[ch][sb] = frame->scale_factor[ch][sb]; + if (bitneed[ch][sb] > max_bitneed) + max_bitneed = bitneed[ch][sb]; + } + } else { + for (sb = 0; sb < subbands; sb++) { + if (frame->scale_factor[ch][sb] == 0) + bitneed[ch][sb] = -5; + else { + if (subbands == 4) + loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb]; + else + loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb]; + if (loudness > 0) + bitneed[ch][sb] = loudness / 2; + else + bitneed[ch][sb] = loudness; + } + if (bitneed[ch][sb] > max_bitneed) + max_bitneed = bitneed[ch][sb]; + } + } + + bitcount = 0; + slicecount = 0; + bitslice = max_bitneed + 1; + do { + bitslice--; + bitcount += slicecount; + slicecount = 0; + for (sb = 0; sb < subbands; sb++) { + if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16)) + slicecount++; + else if (bitneed[ch][sb] == bitslice + 1) + slicecount += 2; + } + } while (bitcount + slicecount < frame->bitpool); + + if (bitcount + slicecount == frame->bitpool) { + bitcount += slicecount; + bitslice--; + } + + for (sb = 0; sb < subbands; sb++) { + if (bitneed[ch][sb] < bitslice + 2) + bits[ch][sb] = 0; + else { + bits[ch][sb] = bitneed[ch][sb] - bitslice; + if (bits[ch][sb] > 16) + bits[ch][sb] = 16; + } + } + + for (sb = 0; bitcount < frame->bitpool && + sb < subbands; sb++) { + if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) { + bits[ch][sb]++; + bitcount++; + } else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) { + bits[ch][sb] = 2; + bitcount += 2; + } + } + + for (sb = 0; bitcount < frame->bitpool && + sb < subbands; sb++) { + if (bits[ch][sb] < 16) { + bits[ch][sb]++; + bitcount++; + } + } + + } + + } else if (frame->mode == STEREO || frame->mode == JOINT_STEREO) { + int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice; + int ch, sb; + + max_bitneed = 0; + if (frame->allocation == SNR) { + for (ch = 0; ch < 2; ch++) { + for (sb = 0; sb < subbands; sb++) { + bitneed[ch][sb] = frame->scale_factor[ch][sb]; + if (bitneed[ch][sb] > max_bitneed) + max_bitneed = bitneed[ch][sb]; + } + } + } else { + for (ch = 0; ch < 2; ch++) { + for (sb = 0; sb < subbands; sb++) { + if (frame->scale_factor[ch][sb] == 0) + bitneed[ch][sb] = -5; + else { + if (subbands == 4) + loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb]; + else + loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb]; + if (loudness > 0) + bitneed[ch][sb] = loudness / 2; + else + bitneed[ch][sb] = loudness; + } + if (bitneed[ch][sb] > max_bitneed) + max_bitneed = bitneed[ch][sb]; + } + } + } + + bitcount = 0; + slicecount = 0; + bitslice = max_bitneed + 1; + do { + bitslice--; + bitcount += slicecount; + slicecount = 0; + for (ch = 0; ch < 2; ch++) { + for (sb = 0; sb < subbands; sb++) { + if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16)) + slicecount++; + else if (bitneed[ch][sb] == bitslice + 1) + slicecount += 2; + } + } + } while (bitcount + slicecount < frame->bitpool); + + if (bitcount + slicecount == frame->bitpool) { + bitcount += slicecount; + bitslice--; + } + + for (ch = 0; ch < 2; ch++) { + for (sb = 0; sb < subbands; sb++) { + if (bitneed[ch][sb] < bitslice + 2) { + bits[ch][sb] = 0; + } else { + bits[ch][sb] = bitneed[ch][sb] - bitslice; + if (bits[ch][sb] > 16) + bits[ch][sb] = 16; + } + } + } + + ch = 0; + sb = 0; + while (bitcount < frame->bitpool) { + if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) { + bits[ch][sb]++; + bitcount++; + } else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) { + bits[ch][sb] = 2; + bitcount += 2; + } + if (ch == 1) { + ch = 0; + sb++; + if (sb >= subbands) + break; + } else + ch = 1; + } + + ch = 0; + sb = 0; + while (bitcount < frame->bitpool) { + if (bits[ch][sb] < 16) { + bits[ch][sb]++; + bitcount++; + } + if (ch == 1) { + ch = 0; + sb++; + if (sb >= subbands) + break; + } else + ch = 1; + } + + } + +} |