diff options
Diffstat (limited to 'ffmpeg/libavcodec/cngdec.c')
| -rw-r--r-- | ffmpeg/libavcodec/cngdec.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/ffmpeg/libavcodec/cngdec.c b/ffmpeg/libavcodec/cngdec.c new file mode 100644 index 0000000..675f77d --- /dev/null +++ b/ffmpeg/libavcodec/cngdec.c @@ -0,0 +1,171 @@ +/* + * RFC 3389 comfort noise generator + * Copyright (c) 2012 Martin Storsjo + * + * 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 <math.h> + +#include "libavutil/common.h" +#include "avcodec.h" +#include "celp_filters.h" +#include "internal.h" +#include "libavutil/lfg.h" + +typedef struct CNGContext { + float *refl_coef, *target_refl_coef; + float *lpc_coef; + int order; + int energy, target_energy; + int inited; + float *filter_out; + float *excitation; + AVLFG lfg; +} CNGContext; + +static av_cold int cng_decode_close(AVCodecContext *avctx) +{ + CNGContext *p = avctx->priv_data; + av_free(p->refl_coef); + av_free(p->target_refl_coef); + av_free(p->lpc_coef); + av_free(p->filter_out); + av_free(p->excitation); + return 0; +} + +static av_cold int cng_decode_init(AVCodecContext *avctx) +{ + CNGContext *p = avctx->priv_data; + + avctx->sample_fmt = AV_SAMPLE_FMT_S16; + avctx->channels = 1; + avctx->sample_rate = 8000; + + p->order = 12; + avctx->frame_size = 640; + p->refl_coef = av_mallocz(p->order * sizeof(*p->refl_coef)); + p->target_refl_coef = av_mallocz(p->order * sizeof(*p->target_refl_coef)); + p->lpc_coef = av_mallocz(p->order * sizeof(*p->lpc_coef)); + p->filter_out = av_mallocz((avctx->frame_size + p->order) * + sizeof(*p->filter_out)); + p->excitation = av_mallocz(avctx->frame_size * sizeof(*p->excitation)); + if (!p->refl_coef || !p->target_refl_coef || !p->lpc_coef || + !p->filter_out || !p->excitation) { + cng_decode_close(avctx); + return AVERROR(ENOMEM); + } + + av_lfg_init(&p->lfg, 0); + + return 0; +} + +static void make_lpc_coefs(float *lpc, const float *refl, int order) +{ + float buf[100]; + float *next, *cur; + int m, i; + next = buf; + cur = lpc; + for (m = 0; m < order; m++) { + next[m] = refl[m]; + for (i = 0; i < m; i++) + next[i] = cur[i] + refl[m] * cur[m - i - 1]; + FFSWAP(float*, next, cur); + } + if (cur != lpc) + memcpy(lpc, cur, sizeof(*lpc) * order); +} + +static void cng_decode_flush(AVCodecContext *avctx) +{ + CNGContext *p = avctx->priv_data; + p->inited = 0; +} + +static int cng_decode_frame(AVCodecContext *avctx, void *data, + int *got_frame_ptr, AVPacket *avpkt) +{ + AVFrame *frame = data; + CNGContext *p = avctx->priv_data; + int buf_size = avpkt->size; + int ret, i; + int16_t *buf_out; + float e = 1.0; + float scaling; + + if (avpkt->size) { + int dbov = -avpkt->data[0]; + p->target_energy = 1081109975 * pow(10, dbov / 10.0) * 0.75; + memset(p->target_refl_coef, 0, p->order * sizeof(*p->target_refl_coef)); + for (i = 0; i < FFMIN(avpkt->size - 1, p->order); i++) { + p->target_refl_coef[i] = (avpkt->data[1 + i] - 127) / 128.0; + } + } + + if (p->inited) { + p->energy = p->energy / 2 + p->target_energy / 2; + for (i = 0; i < p->order; i++) + p->refl_coef[i] = 0.6 *p->refl_coef[i] + 0.4 * p->target_refl_coef[i]; + } else { + p->energy = p->target_energy; + memcpy(p->refl_coef, p->target_refl_coef, p->order * sizeof(*p->refl_coef)); + p->inited = 1; + } + make_lpc_coefs(p->lpc_coef, p->refl_coef, p->order); + + for (i = 0; i < p->order; i++) + e *= 1.0 - p->refl_coef[i]*p->refl_coef[i]; + + scaling = sqrt(e * p->energy / 1081109975); + for (i = 0; i < avctx->frame_size; i++) { + int r = (av_lfg_get(&p->lfg) & 0xffff) - 0x8000; + p->excitation[i] = scaling * r; + } + ff_celp_lp_synthesis_filterf(p->filter_out + p->order, p->lpc_coef, + p->excitation, avctx->frame_size, p->order); + + frame->nb_samples = avctx->frame_size; + if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) + return ret; + buf_out = (int16_t *)frame->data[0]; + for (i = 0; i < avctx->frame_size; i++) + buf_out[i] = p->filter_out[i + p->order]; + memcpy(p->filter_out, p->filter_out + avctx->frame_size, + p->order * sizeof(*p->filter_out)); + + *got_frame_ptr = 1; + + return buf_size; +} + +AVCodec ff_comfortnoise_decoder = { + .name = "comfortnoise", + .type = AVMEDIA_TYPE_AUDIO, + .id = AV_CODEC_ID_COMFORT_NOISE, + .priv_data_size = sizeof(CNGContext), + .init = cng_decode_init, + .decode = cng_decode_frame, + .flush = cng_decode_flush, + .close = cng_decode_close, + .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"), + .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, + AV_SAMPLE_FMT_NONE }, + .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1, +}; |