| /* |
| * G.726 ADPCM audio codec |
| * Copyright (c) 2004 Roman Shaposhnik |
| * |
| * This is a very straightforward rendition of the G.726 |
| * Section 4 "Computational Details". |
| * |
| * 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 |
| */ |
| #include <limits.h> |
| #include "avcodec.h" |
| #include "bitstream.h" |
| |
| /** |
| * G.726 11bit float. |
| * G.726 Standard uses rather odd 11bit floating point arithmentic for |
| * numerous occasions. It's a mistery to me why they did it this way |
| * instead of simply using 32bit integer arithmetic. |
| */ |
| typedef struct Float11 { |
| uint8_t sign; /**< 1bit sign */ |
| uint8_t exp; /**< 4bit exponent */ |
| uint8_t mant; /**< 6bit mantissa */ |
| } Float11; |
| |
| static inline Float11* i2f(int i, Float11* f) |
| { |
| f->sign = (i < 0); |
| if (f->sign) |
| i = -i; |
| f->exp = av_log2_16bit(i) + !!i; |
| f->mant = i? (i<<6) >> f->exp : 1<<5; |
| return f; |
| } |
| |
| static inline int16_t mult(Float11* f1, Float11* f2) |
| { |
| int res, exp; |
| |
| exp = f1->exp + f2->exp; |
| res = (((f1->mant * f2->mant) + 0x30) >> 4); |
| res = exp > 19 ? res << (exp - 19) : res >> (19 - exp); |
| return (f1->sign ^ f2->sign) ? -res : res; |
| } |
| |
| static inline int sgn(int value) |
| { |
| return (value < 0) ? -1 : 1; |
| } |
| |
| typedef struct G726Tables { |
| const int* quant; /**< quantization table */ |
| const int16_t* iquant; /**< inverse quantization table */ |
| const int16_t* W; /**< special table #1 ;-) */ |
| const uint8_t* F; /**< special table #2 */ |
| } G726Tables; |
| |
| typedef struct G726Context { |
| G726Tables tbls; /**< static tables needed for computation */ |
| |
| Float11 sr[2]; /**< prev. reconstructed samples */ |
| Float11 dq[6]; /**< prev. difference */ |
| int a[2]; /**< second order predictor coeffs */ |
| int b[6]; /**< sixth order predictor coeffs */ |
| int pk[2]; /**< signs of prev. 2 sez + dq */ |
| |
| int ap; /**< scale factor control */ |
| int yu; /**< fast scale factor */ |
| int yl; /**< slow scale factor */ |
| int dms; /**< short average magnitude of F[i] */ |
| int dml; /**< long average magnitude of F[i] */ |
| int td; /**< tone detect */ |
| |
| int se; /**< estimated signal for the next iteration */ |
| int sez; /**< estimated second order prediction */ |
| int y; /**< quantizer scaling factor for the next iteration */ |
| int code_size; |
| } G726Context; |
| |
| static const int quant_tbl16[] = /**< 16kbit/s 2bits per sample */ |
| { 260, INT_MAX }; |
| static const int16_t iquant_tbl16[] = |
| { 116, 365, 365, 116 }; |
| static const int16_t W_tbl16[] = |
| { -22, 439, 439, -22 }; |
| static const uint8_t F_tbl16[] = |
| { 0, 7, 7, 0 }; |
| |
| static const int quant_tbl24[] = /**< 24kbit/s 3bits per sample */ |
| { 7, 217, 330, INT_MAX }; |
| static const int16_t iquant_tbl24[] = |
| { INT16_MIN, 135, 273, 373, 373, 273, 135, INT16_MIN }; |
| static const int16_t W_tbl24[] = |
| { -4, 30, 137, 582, 582, 137, 30, -4 }; |
| static const uint8_t F_tbl24[] = |
| { 0, 1, 2, 7, 7, 2, 1, 0 }; |
| |
| static const int quant_tbl32[] = /**< 32kbit/s 4bits per sample */ |
| { -125, 79, 177, 245, 299, 348, 399, INT_MAX }; |
| static const int16_t iquant_tbl32[] = |
| { INT16_MIN, 4, 135, 213, 273, 323, 373, 425, |
| 425, 373, 323, 273, 213, 135, 4, INT16_MIN }; |
| static const int16_t W_tbl32[] = |
| { -12, 18, 41, 64, 112, 198, 355, 1122, |
| 1122, 355, 198, 112, 64, 41, 18, -12}; |
| static const uint8_t F_tbl32[] = |
| { 0, 0, 0, 1, 1, 1, 3, 7, 7, 3, 1, 1, 1, 0, 0, 0 }; |
| |
| static const int quant_tbl40[] = /**< 40kbit/s 5bits per sample */ |
| { -122, -16, 67, 138, 197, 249, 297, 338, |
| 377, 412, 444, 474, 501, 527, 552, INT_MAX }; |
| static const int16_t iquant_tbl40[] = |
| { INT16_MIN, -66, 28, 104, 169, 224, 274, 318, |
| 358, 395, 429, 459, 488, 514, 539, 566, |
| 566, 539, 514, 488, 459, 429, 395, 358, |
| 318, 274, 224, 169, 104, 28, -66, INT16_MIN }; |
| static const int16_t W_tbl40[] = |
| { 14, 14, 24, 39, 40, 41, 58, 100, |
| 141, 179, 219, 280, 358, 440, 529, 696, |
| 696, 529, 440, 358, 280, 219, 179, 141, |
| 100, 58, 41, 40, 39, 24, 14, 14 }; |
| static const uint8_t F_tbl40[] = |
| { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 6, |
| 6, 6, 5, 4, 3, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 }; |
| |
| static const G726Tables G726Tables_pool[] = |
| {{ quant_tbl16, iquant_tbl16, W_tbl16, F_tbl16 }, |
| { quant_tbl24, iquant_tbl24, W_tbl24, F_tbl24 }, |
| { quant_tbl32, iquant_tbl32, W_tbl32, F_tbl32 }, |
| { quant_tbl40, iquant_tbl40, W_tbl40, F_tbl40 }}; |
| |
| |
| /** |
| * Para 4.2.2 page 18: Adaptive quantizer. |
| */ |
| static inline uint8_t quant(G726Context* c, int d) |
| { |
| int sign, exp, i, dln; |
| |
| sign = i = 0; |
| if (d < 0) { |
| sign = 1; |
| d = -d; |
| } |
| exp = av_log2_16bit(d); |
| dln = ((exp<<7) + (((d<<7)>>exp)&0x7f)) - (c->y>>2); |
| |
| while (c->tbls.quant[i] < INT_MAX && c->tbls.quant[i] < dln) |
| ++i; |
| |
| if (sign) |
| i = ~i; |
| if (c->code_size != 2 && i == 0) /* I'm not sure this is a good idea */ |
| i = 0xff; |
| |
| return i; |
| } |
| |
| /** |
| * Para 4.2.3 page 22: Inverse adaptive quantizer. |
| */ |
| static inline int16_t inverse_quant(G726Context* c, int i) |
| { |
| int dql, dex, dqt; |
| |
| dql = c->tbls.iquant[i] + (c->y >> 2); |
| dex = (dql>>7) & 0xf; /* 4bit exponent */ |
| dqt = (1<<7) + (dql & 0x7f); /* log2 -> linear */ |
| return (dql < 0) ? 0 : ((dqt<<dex) >> 7); |
| } |
| |
| static int16_t g726_decode(G726Context* c, int I) |
| { |
| int dq, re_signal, pk0, fa1, i, tr, ylint, ylfrac, thr2, al, dq0; |
| Float11 f; |
| int I_sig= I >> (c->code_size - 1); |
| |
| dq = inverse_quant(c, I); |
| |
| /* Transition detect */ |
| ylint = (c->yl >> 15); |
| ylfrac = (c->yl >> 10) & 0x1f; |
| thr2 = (ylint > 9) ? 0x1f << 10 : (0x20 + ylfrac) << ylint; |
| tr= (c->td == 1 && dq > ((3*thr2)>>2)); |
| |
| if (I_sig) /* get the sign */ |
| dq = -dq; |
| re_signal = c->se + dq; |
| |
| /* Update second order predictor coefficient A2 and A1 */ |
| pk0 = (c->sez + dq) ? sgn(c->sez + dq) : 0; |
| dq0 = dq ? sgn(dq) : 0; |
| if (tr) { |
| c->a[0] = 0; |
| c->a[1] = 0; |
| for (i=0; i<6; i++) |
| c->b[i] = 0; |
| } else { |
| /* This is a bit crazy, but it really is +255 not +256 */ |
| fa1 = av_clip((-c->a[0]*c->pk[0]*pk0)>>5, -256, 255); |
| |
| c->a[1] += 128*pk0*c->pk[1] + fa1 - (c->a[1]>>7); |
| c->a[1] = av_clip(c->a[1], -12288, 12288); |
| c->a[0] += 64*3*pk0*c->pk[0] - (c->a[0] >> 8); |
| c->a[0] = av_clip(c->a[0], -(15360 - c->a[1]), 15360 - c->a[1]); |
| |
| for (i=0; i<6; i++) |
| c->b[i] += 128*dq0*sgn(-c->dq[i].sign) - (c->b[i]>>8); |
| } |
| |
| /* Update Dq and Sr and Pk */ |
| c->pk[1] = c->pk[0]; |
| c->pk[0] = pk0 ? pk0 : 1; |
| c->sr[1] = c->sr[0]; |
| i2f(re_signal, &c->sr[0]); |
| for (i=5; i>0; i--) |
| c->dq[i] = c->dq[i-1]; |
| i2f(dq, &c->dq[0]); |
| c->dq[0].sign = I_sig; /* Isn't it crazy ?!?! */ |
| |
| c->td = c->a[1] < -11776; |
| |
| /* Update Ap */ |
| c->dms += (c->tbls.F[I]<<4) + ((- c->dms) >> 5); |
| c->dml += (c->tbls.F[I]<<4) + ((- c->dml) >> 7); |
| if (tr) |
| c->ap = 256; |
| else { |
| c->ap += (-c->ap) >> 4; |
| if (c->y <= 1535 || c->td || abs((c->dms << 2) - c->dml) >= (c->dml >> 3)) |
| c->ap += 0x20; |
| } |
| |
| /* Update Yu and Yl */ |
| c->yu = av_clip(c->y + c->tbls.W[I] + ((-c->y)>>5), 544, 5120); |
| c->yl += c->yu + ((-c->yl)>>6); |
| |
| /* Next iteration for Y */ |
| al = (c->ap >= 256) ? 1<<6 : c->ap >> 2; |
| c->y = (c->yl + (c->yu - (c->yl>>6))*al) >> 6; |
| |
| /* Next iteration for SE and SEZ */ |
| c->se = 0; |
| for (i=0; i<6; i++) |
| c->se += mult(i2f(c->b[i] >> 2, &f), &c->dq[i]); |
| c->sez = c->se >> 1; |
| for (i=0; i<2; i++) |
| c->se += mult(i2f(c->a[i] >> 2, &f), &c->sr[i]); |
| c->se >>= 1; |
| |
| return av_clip(re_signal << 2, -0xffff, 0xffff); |
| } |
| |
| static av_cold int g726_reset(G726Context* c, int index) |
| { |
| int i; |
| |
| c->tbls = G726Tables_pool[index]; |
| for (i=0; i<2; i++) { |
| c->sr[i].mant = 1<<5; |
| c->pk[i] = 1; |
| } |
| for (i=0; i<6; i++) { |
| c->dq[i].mant = 1<<5; |
| } |
| c->yu = 544; |
| c->yl = 34816; |
| |
| c->y = 544; |
| |
| return 0; |
| } |
| |
| #if CONFIG_ADPCM_G726_ENCODER |
| static int16_t g726_encode(G726Context* c, int16_t sig) |
| { |
| uint8_t i; |
| |
| i = quant(c, sig/4 - c->se) & ((1<<c->code_size) - 1); |
| g726_decode(c, i); |
| return i; |
| } |
| #endif |
| |
| /* Interfacing to the libavcodec */ |
| |
| static av_cold int g726_init(AVCodecContext * avctx) |
| { |
| G726Context* c = avctx->priv_data; |
| unsigned int index; |
| |
| if (avctx->sample_rate <= 0) { |
| av_log(avctx, AV_LOG_ERROR, "Samplerate is invalid\n"); |
| return -1; |
| } |
| |
| index = (avctx->bit_rate + avctx->sample_rate/2) / avctx->sample_rate - 2; |
| |
| if (avctx->bit_rate % avctx->sample_rate && avctx->codec->encode) { |
| av_log(avctx, AV_LOG_ERROR, "Bitrate - Samplerate combination is invalid\n"); |
| return -1; |
| } |
| if(avctx->channels != 1){ |
| av_log(avctx, AV_LOG_ERROR, "Only mono is supported\n"); |
| return -1; |
| } |
| if(index>3){ |
| av_log(avctx, AV_LOG_ERROR, "Unsupported number of bits %d\n", index+2); |
| return -1; |
| } |
| g726_reset(c, index); |
| c->code_size = index+2; |
| |
| avctx->coded_frame = avcodec_alloc_frame(); |
| if (!avctx->coded_frame) |
| return AVERROR(ENOMEM); |
| avctx->coded_frame->key_frame = 1; |
| |
| if (avctx->codec->decode) |
| avctx->sample_fmt = SAMPLE_FMT_S16; |
| |
| return 0; |
| } |
| |
| static av_cold int g726_close(AVCodecContext *avctx) |
| { |
| av_freep(&avctx->coded_frame); |
| return 0; |
| } |
| |
| #if CONFIG_ADPCM_G726_ENCODER |
| static int g726_encode_frame(AVCodecContext *avctx, |
| uint8_t *dst, int buf_size, void *data) |
| { |
| G726Context *c = avctx->priv_data; |
| short *samples = data; |
| PutBitContext pb; |
| |
| init_put_bits(&pb, dst, 1024*1024); |
| |
| for (; buf_size; buf_size--) |
| put_bits(&pb, c->code_size, g726_encode(c, *samples++)); |
| |
| flush_put_bits(&pb); |
| |
| return put_bits_count(&pb)>>3; |
| } |
| #endif |
| |
| static int g726_decode_frame(AVCodecContext *avctx, |
| void *data, int *data_size, |
| const uint8_t *buf, int buf_size) |
| { |
| G726Context *c = avctx->priv_data; |
| short *samples = data; |
| GetBitContext gb; |
| |
| init_get_bits(&gb, buf, buf_size * 8); |
| |
| while (get_bits_count(&gb) + c->code_size <= buf_size*8) |
| *samples++ = g726_decode(c, get_bits(&gb, c->code_size)); |
| |
| if(buf_size*8 != get_bits_count(&gb)) |
| av_log(avctx, AV_LOG_ERROR, "Frame invalidly split, missing parser?\n"); |
| |
| *data_size = (uint8_t*)samples - (uint8_t*)data; |
| return buf_size; |
| } |
| |
| #if CONFIG_ADPCM_G726_ENCODER |
| AVCodec adpcm_g726_encoder = { |
| "g726", |
| CODEC_TYPE_AUDIO, |
| CODEC_ID_ADPCM_G726, |
| sizeof(G726Context), |
| g726_init, |
| g726_encode_frame, |
| g726_close, |
| NULL, |
| .sample_fmts = (enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE}, |
| .long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"), |
| }; |
| #endif |
| |
| AVCodec adpcm_g726_decoder = { |
| "g726", |
| CODEC_TYPE_AUDIO, |
| CODEC_ID_ADPCM_G726, |
| sizeof(G726Context), |
| g726_init, |
| NULL, |
| g726_close, |
| g726_decode_frame, |
| .long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"), |
| }; |
