/* * G.728 decoder * Copyright (c) 2025 Peter Ross * * 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 "avcodec.h" #include "celp_filters.h" #include "codec_internal.h" #include "decode.h" #include "get_bits.h" #include "g728data.h" #include "lpc_functions.h" #include "ra288.h" #include "libavutil/float_dsp.h" #include "libavutil/mem.h" #include "libavutil/mem_internal.h" #include "libavutil/opt.h" #include "libavutil/thread.h" #define MAX_BACKWARD_FILTER_ORDER LPC #define MAX_BACKWARD_FILTER_LEN NFRSZ #define MAX_BACKWARD_FILTER_NONREC NONR #define ATTEN 0.75f #include "g728_template.c" #define LPCW 10 /* Perceptual weighting filter order */ #define GOFF 32.0f /* Log-gain offset value */ static float g728_gq_db[8]; static float g728_y_db[128]; static DECLARE_ALIGNED(32, float, g728_wnr_r)[FFALIGN(NSBSZ,16)]; static DECLARE_ALIGNED(32, float, g728_wnrg_r)[FFALIGN(NSBGSZ, 16)]; static DECLARE_ALIGNED(32, float, g728_facv_f)[FFALIGN(LPC, 16)]; static av_cold void g728_init_static_data(void) { for(int i = 0; i < FF_ARRAY_ELEMS(amptable); i++) g728_gq_db[i] = 10.0f*log10f(amptable[i] * amptable[i]); for (int i = 0; i < FF_ARRAY_ELEMS(codetable); i++) { float cby[IDIM]; for (int j = 0; j < IDIM; j++) cby[j] = codetable[i][j] * (1.0f/(1<<11)); g728_y_db[i] = 10.0f*log10f(ff_scalarproduct_float_c(cby, cby, IDIM) / IDIM); } for (int i = 0; i < NSBSZ; i++) g728_wnr_r[i] = g728_wnr[NSBSZ - 1 - i] * (1.0f/(1<<15)); for (int i = 0; i < NSBGSZ; i++) g728_wnrg_r[i] = g728_wnrg[NSBGSZ - 1 - i] * (1.0f/(1<<15)); for (int i = 0; i < LPC; i++) g728_facv_f[i] = g728_facv[i] * (1.0f/(1<<14)); } typedef struct { AVFloatDSPContext *fdsp; int valid; float a[LPC]; DECLARE_ALIGNED(32, float, sb)[NSBSZ]; DECLARE_ALIGNED(32, float, sbg)[NSBGSZ]; DECLARE_ALIGNED(32, float, gp)[FFALIGN(LPCLG, 16)]; DECLARE_ALIGNED(32, float, atmp)[FFALIGN(LPC, 16)]; float rexp[LPC + 1]; float rexpg[LPCLG + 1]; float r[LPC + 1]; float alpha; } G728Context; static av_cold int g728_decode_init(AVCodecContext *avctx) { static AVOnce init_static_once = AV_ONCE_INIT; G728Context *s = avctx->priv_data; s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT); if (!s->fdsp) return AVERROR(ENOMEM); s->gp[0] = -1.0f; for (int i = 0; i < NUPDATE; i++) s->sbg[NSBGSZ - 1 -i] = -GOFF; avctx->sample_fmt = AV_SAMPLE_FMT_FLT; av_channel_layout_uninit(&avctx->ch_layout); avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO; ff_thread_once(&init_static_once, g728_init_static_data); return 0; } static av_cold int g728_decode_close(AVCodecContext *avctx) { G728Context *s = avctx->priv_data; av_freep(&s->fdsp); return 0; } static int hybrid_window(AVFloatDSPContext *fdsp, int order, int n, int non_rec, float *out, const float *hist, float *out2, const float *window) { do_hybrid_window(fdsp->vector_fmul, order, n, non_rec, out, hist, out2, window); return out[order] != 0.0f; } static void decode_frame(G728Context *s, GetBitContext *gb, float *dst) { float *gstate = s->sbg + NSBGSZ - 2; for (int idx = 0; idx < NUPDATE; idx++) { DECLARE_ALIGNED(32, float, et)[IDIM]; float *statelpc = s->sb + NSBSZ - NFRSZ + idx*IDIM; float gain, gain_db; int is, ig; gain_db = 0.0f; for (int i = 0; i < LPCLG; i++) gain_db -= s->gp[i] * gstate[-i]; gain_db = av_clipf(gain_db, -GOFF, 28.0f); is = get_bits(gb, 7); // shape index ig = get_bits(gb, 3); // gain index gain = powf(10.0f, (gain_db + GOFF) * .05f) * amptable[ig] * (1.0f/(1<<11)); for (int i = 0; i < IDIM; i++) et[i] = codetable[is][i] * gain; ff_celp_lp_synthesis_filterf(statelpc, s->a, et, IDIM, LPC); for (int i = 0; i < IDIM; i++) { statelpc[i] = av_clipf(statelpc[i], -4095.0f, 4095.0f); dst[idx*IDIM + i] = statelpc[i] * (1.0f/(1<<12)); } gstate++; *gstate = FFMAX(-GOFF, g728_gq_db[ig] + g728_y_db[is] + gain_db); if (idx == 0) { DECLARE_ALIGNED(32, float, gptmp)[FFALIGN(LPCLG, 16)]; if (s->valid && (s->valid = !compute_lpc_coefs(s->r + 1, LPCW, LPC, s->atmp, 0, 0, 1, &s->alpha))) { s->fdsp->vector_fmul(s->atmp, s->atmp, g728_facv_f, FFALIGN(LPC, 16)); } if (hybrid_window(s->fdsp, LPCLG, NUPDATE, NONRLG, s->r, s->sbg, s->rexpg, g728_wnrg_r) && !compute_lpc_coefs(s->r, 0, LPCLG, gptmp, 0, 0, 1, &s->alpha)) { s->fdsp->vector_fmul(s->gp, gptmp, gain_bw_tab, FFALIGN(LPCLG, 16)); } memmove(s->sbg, s->sbg + NUPDATE, sizeof(float)*(LPCLG + NONRLG)); gstate = s->sbg + NSBGSZ - 1 - NUPDATE; } else if (idx == 1) { if (s->valid) memcpy(s->a, s->atmp, sizeof(float)*LPC); } } s->valid = 0; if (hybrid_window(s->fdsp, LPC, NFRSZ, NONR, s->r, s->sb, s->rexp, g728_wnr_r)) { s->valid = !compute_lpc_coefs(s->r, 0, LPCW, s->atmp, 0, 0, 1, &s->alpha); } memmove(s->sb, s->sb + NFRSZ, sizeof(float)*(LPC + NONR)); } static int g728_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt) { G728Context *s = avctx->priv_data; GetBitContext gb; int ret; int nb_frames = avpkt->size / 5; if (!nb_frames) return AVERROR_INVALIDDATA; if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0) return ret; #define SAMPLES_PER_FRAME 20 frame->nb_samples = nb_frames * SAMPLES_PER_FRAME; if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) return ret; for (int i = 0; i < nb_frames; i++) decode_frame(s, &gb, (float *)frame->data[0] + i * 20); *got_frame_ptr = 1; return nb_frames * 5; } const FFCodec ff_g728_decoder = { .p.name = "g728", CODEC_LONG_NAME("G.728)"), .p.type = AVMEDIA_TYPE_AUDIO, .p.id = AV_CODEC_ID_G728, .priv_data_size = sizeof(G728Context), .init = g728_decode_init, .close = g728_decode_close, FF_CODEC_DECODE_CB(g728_decode_frame), .p.capabilities = AV_CODEC_CAP_CHANNEL_CONF | AV_CODEC_CAP_DR1, };