blob: 302c703f7216ae3163452b8160ccf8b55f3928a2
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_packet2(avctx, avpkt, 1 + p->order, 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_uintp2(-floor(dbov), 7); |
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 | av_assert1(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 | }; |
117 |