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 "avcodec.h"
25 #include "bytestream.h"
26 #include "internal.h"
27 #include "mathops.h"
28
29 #define ROQ_FRAME_SIZE 735
30 #define ROQ_HEADER_SIZE 8
31
32 #define MAX_DPCM (127*127)
33
34
35 typedef struct ROQDPCMContext {
36 short lastSample[2];
37 int input_frames;
38 int buffered_samples;
39 int16_t *frame_buffer;
40 int64_t first_pts;
41 } ROQDPCMContext;
42
43
roq_dpcm_encode_close(AVCodecContext * avctx)44 static av_cold int roq_dpcm_encode_close(AVCodecContext *avctx)
45 {
46 ROQDPCMContext *context = avctx->priv_data;
47
48 av_freep(&context->frame_buffer);
49
50 return 0;
51 }
52
roq_dpcm_encode_init(AVCodecContext * avctx)53 static av_cold int roq_dpcm_encode_init(AVCodecContext *avctx)
54 {
55 ROQDPCMContext *context = avctx->priv_data;
56
57 if (avctx->channels > 2) {
58 av_log(avctx, AV_LOG_ERROR, "Audio must be mono or stereo\n");
59 return AVERROR(EINVAL);
60 }
61 if (avctx->sample_rate != 22050) {
62 av_log(avctx, AV_LOG_ERROR, "Audio must be 22050 Hz\n");
63 return AVERROR(EINVAL);
64 }
65
66 avctx->frame_size = ROQ_FRAME_SIZE;
67 avctx->bit_rate = (ROQ_HEADER_SIZE + ROQ_FRAME_SIZE * avctx->channels) *
68 (22050 / ROQ_FRAME_SIZE) * 8;
69
70 context->frame_buffer = av_malloc(8 * ROQ_FRAME_SIZE * avctx->channels *
71 sizeof(*context->frame_buffer));
72 if (!context->frame_buffer)
73 return AVERROR(ENOMEM);
74
75 context->lastSample[0] = context->lastSample[1] = 0;
76
77 return 0;
78 }
79
dpcm_predict(short * previous,short current)80 static unsigned char dpcm_predict(short *previous, short current)
81 {
82 int diff;
83 int negative;
84 int result;
85 int predicted;
86
87 diff = current - *previous;
88
89 negative = diff<0;
90 diff = FFABS(diff);
91
92 if (diff >= MAX_DPCM)
93 result = 127;
94 else {
95 result = ff_sqrt(diff);
96 result += diff > result*result+result;
97 }
98
99 /* See if this overflows */
100 retry:
101 diff = result*result;
102 if (negative)
103 diff = -diff;
104 predicted = *previous + diff;
105
106 /* If it overflows, back off a step */
107 if (predicted > 32767 || predicted < -32768) {
108 result--;
109 goto retry;
110 }
111
112 /* Add the sign bit */
113 result |= negative << 7; //if (negative) result |= 128;
114
115 *previous = predicted;
116
117 return result;
118 }
119
roq_dpcm_encode_frame(AVCodecContext * avctx,AVPacket * avpkt,const AVFrame * frame,int * got_packet_ptr)120 static int roq_dpcm_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
121 const AVFrame *frame, int *got_packet_ptr)
122 {
123 int i, stereo, data_size, ret;
124 const int16_t *in = frame ? (const int16_t *)frame->data[0] : NULL;
125 uint8_t *out;
126 ROQDPCMContext *context = avctx->priv_data;
127
128 stereo = (avctx->channels == 2);
129
130 if (!in && context->input_frames >= 8)
131 return 0;
132
133 if (in && context->input_frames < 8) {
134 memcpy(&context->frame_buffer[context->buffered_samples * avctx->channels],
135 in, avctx->frame_size * avctx->channels * sizeof(*in));
136 context->buffered_samples += avctx->frame_size;
137 if (context->input_frames == 0)
138 context->first_pts = frame->pts;
139 if (context->input_frames < 7) {
140 context->input_frames++;
141 return 0;
142 }
143 }
144 if (context->input_frames < 8)
145 in = context->frame_buffer;
146
147 if (stereo) {
148 context->lastSample[0] &= 0xFF00;
149 context->lastSample[1] &= 0xFF00;
150 }
151
152 if (context->input_frames == 7)
153 data_size = avctx->channels * context->buffered_samples;
154 else
155 data_size = avctx->channels * avctx->frame_size;
156
157 if ((ret = ff_alloc_packet2(avctx, avpkt, ROQ_HEADER_SIZE + data_size, 0)) < 0)
158 return ret;
159 out = avpkt->data;
160
161 bytestream_put_byte(&out, stereo ? 0x21 : 0x20);
162 bytestream_put_byte(&out, 0x10);
163 bytestream_put_le32(&out, data_size);
164
165 if (stereo) {
166 bytestream_put_byte(&out, (context->lastSample[1])>>8);
167 bytestream_put_byte(&out, (context->lastSample[0])>>8);
168 } else
169 bytestream_put_le16(&out, context->lastSample[0]);
170
171 /* Write the actual samples */
172 for (i = 0; i < data_size; i++)
173 *out++ = dpcm_predict(&context->lastSample[i & 1], *in++);
174
175 avpkt->pts = context->input_frames <= 7 ? context->first_pts : frame->pts;
176 avpkt->duration = data_size / avctx->channels;
177
178 context->input_frames++;
179 if (!in)
180 context->input_frames = FFMAX(context->input_frames, 8);
181
182 *got_packet_ptr = 1;
183 return 0;
184 }
185
186 AVCodec ff_roq_dpcm_encoder = {
187 .name = "roq_dpcm",
188 .long_name = NULL_IF_CONFIG_SMALL("id RoQ DPCM"),
189 .type = AVMEDIA_TYPE_AUDIO,
190 .id = AV_CODEC_ID_ROQ_DPCM,
191 .priv_data_size = sizeof(ROQDPCMContext),
192 .init = roq_dpcm_encode_init,
193 .encode2 = roq_dpcm_encode_frame,
194 .close = roq_dpcm_encode_close,
195 .capabilities = AV_CODEC_CAP_DELAY,
196 .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
197 AV_SAMPLE_FMT_NONE },
198 };
199