Move ff_sqrt() to libavutil/intmath.h
[libav.git] / libavcodec / roqaudioenc.c
1 /*
2 * RoQ audio encoder
3 *
4 * Copyright (c) 2005 Eric Lasota
5 * Based on RoQ specs (c)2001 Tim Ferguson
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 #include "libavutil/intmath.h"
25 #include "avcodec.h"
26 #include "bytestream.h"
27
28 #define ROQ_FIRST_FRAME_SIZE (735*8)
29 #define ROQ_FRAME_SIZE 735
30
31
32 #define MAX_DPCM (127*127)
33
34
35 typedef struct
36 {
37 short lastSample[2];
38 } ROQDPCMContext;
39
40 static av_cold int roq_dpcm_encode_init(AVCodecContext *avctx)
41 {
42 ROQDPCMContext *context = avctx->priv_data;
43
44 if (avctx->channels > 2) {
45 av_log(avctx, AV_LOG_ERROR, "Audio must be mono or stereo\n");
46 return -1;
47 }
48 if (avctx->sample_rate != 22050) {
49 av_log(avctx, AV_LOG_ERROR, "Audio must be 22050 Hz\n");
50 return -1;
51 }
52 if (avctx->sample_fmt != SAMPLE_FMT_S16) {
53 av_log(avctx, AV_LOG_ERROR, "Audio must be signed 16-bit\n");
54 return -1;
55 }
56
57 avctx->frame_size = ROQ_FIRST_FRAME_SIZE;
58
59 context->lastSample[0] = context->lastSample[1] = 0;
60
61 avctx->coded_frame= avcodec_alloc_frame();
62 avctx->coded_frame->key_frame= 1;
63
64 return 0;
65 }
66
67 static unsigned char dpcm_predict(short *previous, short current)
68 {
69 int diff;
70 int negative;
71 int result;
72 int predicted;
73
74 diff = current - *previous;
75
76 negative = diff<0;
77 diff = FFABS(diff);
78
79 if (diff >= MAX_DPCM)
80 result = 127;
81 else {
82 result = ff_sqrt(diff);
83 result += diff > result*result+result;
84 }
85
86 /* See if this overflows */
87 retry:
88 diff = result*result;
89 if (negative)
90 diff = -diff;
91 predicted = *previous + diff;
92
93 /* If it overflows, back off a step */
94 if (predicted > 32767 || predicted < -32768) {
95 result--;
96 goto retry;
97 }
98
99 /* Add the sign bit */
100 result |= negative << 7; //if (negative) result |= 128;
101
102 *previous = predicted;
103
104 return result;
105 }
106
107 static int roq_dpcm_encode_frame(AVCodecContext *avctx,
108 unsigned char *frame, int buf_size, void *data)
109 {
110 int i, samples, stereo, ch;
111 short *in;
112 unsigned char *out;
113
114 ROQDPCMContext *context = avctx->priv_data;
115
116 stereo = (avctx->channels == 2);
117
118 if (stereo) {
119 context->lastSample[0] &= 0xFF00;
120 context->lastSample[1] &= 0xFF00;
121 }
122
123 out = frame;
124 in = data;
125
126 bytestream_put_byte(&out, stereo ? 0x21 : 0x20);
127 bytestream_put_byte(&out, 0x10);
128 bytestream_put_le32(&out, avctx->frame_size*avctx->channels);
129
130 if (stereo) {
131 bytestream_put_byte(&out, (context->lastSample[1])>>8);
132 bytestream_put_byte(&out, (context->lastSample[0])>>8);
133 } else
134 bytestream_put_le16(&out, context->lastSample[0]);
135
136 /* Write the actual samples */
137 samples = avctx->frame_size;
138 for (i=0; i<samples; i++)
139 for (ch=0; ch<avctx->channels; ch++)
140 *out++ = dpcm_predict(&context->lastSample[ch], *in++);
141
142 /* Use smaller frames from now on */
143 avctx->frame_size = ROQ_FRAME_SIZE;
144
145 /* Return the result size */
146 return out - frame;
147 }
148
149 static av_cold int roq_dpcm_encode_close(AVCodecContext *avctx)
150 {
151 av_freep(&avctx->coded_frame);
152
153 return 0;
154 }
155
156 AVCodec roq_dpcm_encoder = {
157 "roq_dpcm",
158 CODEC_TYPE_AUDIO,
159 CODEC_ID_ROQ_DPCM,
160 sizeof(ROQDPCMContext),
161 roq_dpcm_encode_init,
162 roq_dpcm_encode_frame,
163 roq_dpcm_encode_close,
164 NULL,
165 .sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
166 .long_name = NULL_IF_CONFIG_SMALL("id RoQ DPCM"),
167 };