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1 | /* |
2 | * RFC 3389 comfort noise generator | |
3 | * Copyright (c) 2012 Martin Storsjo | |
4 | * | |
5 | * This file is part of FFmpeg. | |
6 | * | |
7 | * FFmpeg is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU Lesser General Public | |
9 | * License as published by the Free Software Foundation; either | |
10 | * version 2.1 of the License, or (at your option) any later version. | |
11 | * | |
12 | * FFmpeg is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | * Lesser General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU Lesser General Public | |
18 | * License along with FFmpeg; if not, write to the Free Software | |
19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
20 | */ | |
21 | ||
22 | #include <math.h> | |
23 | ||
24 | #include "libavutil/common.h" | |
25 | #include "avcodec.h" | |
26 | #include "internal.h" | |
27 | #include "lpc.h" | |
28 | ||
29 | typedef struct CNGContext { | |
30 | LPCContext lpc; | |
31 | int order; | |
32 | int32_t *samples32; | |
33 | double *ref_coef; | |
34 | } CNGContext; | |
35 | ||
36 | static av_cold int cng_encode_close(AVCodecContext *avctx) | |
37 | { | |
38 | CNGContext *p = avctx->priv_data; | |
39 | ff_lpc_end(&p->lpc); | |
40 | av_free(p->samples32); | |
41 | av_free(p->ref_coef); | |
42 | return 0; | |
43 | } | |
44 | ||
45 | static av_cold int cng_encode_init(AVCodecContext *avctx) | |
46 | { | |
47 | CNGContext *p = avctx->priv_data; | |
48 | int ret; | |
49 | ||
50 | if (avctx->channels != 1) { | |
51 | av_log(avctx, AV_LOG_ERROR, "Only mono supported\n"); | |
52 | return AVERROR(EINVAL); | |
53 | } | |
54 | ||
55 | avctx->frame_size = 640; | |
56 | p->order = 10; | |
57 | if ((ret = ff_lpc_init(&p->lpc, avctx->frame_size, p->order, FF_LPC_TYPE_LEVINSON)) < 0) | |
58 | return ret; | |
59 | p->samples32 = av_malloc_array(avctx->frame_size, sizeof(*p->samples32)); | |
60 | p->ref_coef = av_malloc_array(p->order, sizeof(*p->ref_coef)); | |
61 | if (!p->samples32 || !p->ref_coef) { | |
62 | cng_encode_close(avctx); | |
63 | return AVERROR(ENOMEM); | |
64 | } | |
65 | ||
66 | return 0; | |
67 | } | |
68 | ||
69 | static int cng_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, | |
70 | const AVFrame *frame, int *got_packet_ptr) | |
71 | { | |
72 | CNGContext *p = avctx->priv_data; | |
73 | int ret, i; | |
74 | double energy = 0; | |
75 | int qdbov; | |
76 | int16_t *samples = (int16_t*) frame->data[0]; | |
77 | ||
78 | if ((ret = ff_alloc_packet(avpkt, 1 + p->order))) { | |
79 | av_log(avctx, AV_LOG_ERROR, "Error getting output packet\n"); | |
80 | return ret; | |
81 | } | |
82 | ||
83 | for (i = 0; i < frame->nb_samples; i++) { | |
84 | p->samples32[i] = samples[i]; | |
85 | energy += samples[i] * samples[i]; | |
86 | } | |
87 | energy /= frame->nb_samples; | |
88 | if (energy > 0) { | |
89 | double dbov = 10 * log10(energy / 1081109975); | |
90 | qdbov = av_clip(-floor(dbov), 0, 127); | |
91 | } else { | |
92 | qdbov = 127; | |
93 | } | |
94 | ret = ff_lpc_calc_ref_coefs(&p->lpc, p->samples32, p->order, p->ref_coef); | |
95 | avpkt->data[0] = qdbov; | |
96 | for (i = 0; i < p->order; i++) | |
97 | avpkt->data[1 + i] = p->ref_coef[i] * 127 + 127; | |
98 | ||
99 | *got_packet_ptr = 1; | |
100 | avpkt->size = 1 + p->order; | |
101 | ||
102 | return 0; | |
103 | } | |
104 | ||
105 | AVCodec ff_comfortnoise_encoder = { | |
106 | .name = "comfortnoise", | |
107 | .long_name = NULL_IF_CONFIG_SMALL("RFC 3389 comfort noise generator"), | |
108 | .type = AVMEDIA_TYPE_AUDIO, | |
109 | .id = AV_CODEC_ID_COMFORT_NOISE, | |
110 | .priv_data_size = sizeof(CNGContext), | |
111 | .init = cng_encode_init, | |
112 | .encode2 = cng_encode_frame, | |
113 | .close = cng_encode_close, | |
114 | .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, | |
115 | AV_SAMPLE_FMT_NONE }, | |
116 | }; |