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2ba45a60 DM |
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 | |
36 | { | |
37 | short lastSample[2]; | |
38 | int input_frames; | |
39 | int buffered_samples; | |
40 | int16_t *frame_buffer; | |
41 | int64_t first_pts; | |
42 | } ROQDPCMContext; | |
43 | ||
44 | ||
45 | static av_cold int roq_dpcm_encode_close(AVCodecContext *avctx) | |
46 | { | |
47 | ROQDPCMContext *context = avctx->priv_data; | |
48 | ||
49 | av_freep(&context->frame_buffer); | |
50 | ||
51 | return 0; | |
52 | } | |
53 | ||
54 | static av_cold int roq_dpcm_encode_init(AVCodecContext *avctx) | |
55 | { | |
56 | ROQDPCMContext *context = avctx->priv_data; | |
57 | int ret; | |
58 | ||
59 | if (avctx->channels > 2) { | |
60 | av_log(avctx, AV_LOG_ERROR, "Audio must be mono or stereo\n"); | |
61 | return AVERROR(EINVAL); | |
62 | } | |
63 | if (avctx->sample_rate != 22050) { | |
64 | av_log(avctx, AV_LOG_ERROR, "Audio must be 22050 Hz\n"); | |
65 | return AVERROR(EINVAL); | |
66 | } | |
67 | ||
68 | avctx->frame_size = ROQ_FRAME_SIZE; | |
69 | avctx->bit_rate = (ROQ_HEADER_SIZE + ROQ_FRAME_SIZE * avctx->channels) * | |
70 | (22050 / ROQ_FRAME_SIZE) * 8; | |
71 | ||
72 | context->frame_buffer = av_malloc(8 * ROQ_FRAME_SIZE * avctx->channels * | |
73 | sizeof(*context->frame_buffer)); | |
74 | if (!context->frame_buffer) { | |
75 | ret = AVERROR(ENOMEM); | |
76 | goto error; | |
77 | } | |
78 | ||
79 | context->lastSample[0] = context->lastSample[1] = 0; | |
80 | ||
81 | return 0; | |
82 | error: | |
83 | roq_dpcm_encode_close(avctx); | |
84 | return ret; | |
85 | } | |
86 | ||
87 | static unsigned char dpcm_predict(short *previous, short current) | |
88 | { | |
89 | int diff; | |
90 | int negative; | |
91 | int result; | |
92 | int predicted; | |
93 | ||
94 | diff = current - *previous; | |
95 | ||
96 | negative = diff<0; | |
97 | diff = FFABS(diff); | |
98 | ||
99 | if (diff >= MAX_DPCM) | |
100 | result = 127; | |
101 | else { | |
102 | result = ff_sqrt(diff); | |
103 | result += diff > result*result+result; | |
104 | } | |
105 | ||
106 | /* See if this overflows */ | |
107 | retry: | |
108 | diff = result*result; | |
109 | if (negative) | |
110 | diff = -diff; | |
111 | predicted = *previous + diff; | |
112 | ||
113 | /* If it overflows, back off a step */ | |
114 | if (predicted > 32767 || predicted < -32768) { | |
115 | result--; | |
116 | goto retry; | |
117 | } | |
118 | ||
119 | /* Add the sign bit */ | |
120 | result |= negative << 7; //if (negative) result |= 128; | |
121 | ||
122 | *previous = predicted; | |
123 | ||
124 | return result; | |
125 | } | |
126 | ||
127 | static int roq_dpcm_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, | |
128 | const AVFrame *frame, int *got_packet_ptr) | |
129 | { | |
130 | int i, stereo, data_size, ret; | |
131 | const int16_t *in = frame ? (const int16_t *)frame->data[0] : NULL; | |
132 | uint8_t *out; | |
133 | ROQDPCMContext *context = avctx->priv_data; | |
134 | ||
135 | stereo = (avctx->channels == 2); | |
136 | ||
137 | if (!in && context->input_frames >= 8) | |
138 | return 0; | |
139 | ||
140 | if (in && context->input_frames < 8) { | |
141 | memcpy(&context->frame_buffer[context->buffered_samples * avctx->channels], | |
142 | in, avctx->frame_size * avctx->channels * sizeof(*in)); | |
143 | context->buffered_samples += avctx->frame_size; | |
144 | if (context->input_frames == 0) | |
145 | context->first_pts = frame->pts; | |
146 | if (context->input_frames < 7) { | |
147 | context->input_frames++; | |
148 | return 0; | |
149 | } | |
150 | } | |
f6fa7814 | 151 | if (context->input_frames < 8) |
2ba45a60 | 152 | in = context->frame_buffer; |
2ba45a60 DM |
153 | |
154 | if (stereo) { | |
155 | context->lastSample[0] &= 0xFF00; | |
156 | context->lastSample[1] &= 0xFF00; | |
157 | } | |
158 | ||
159 | if (context->input_frames == 7) | |
160 | data_size = avctx->channels * context->buffered_samples; | |
161 | else | |
162 | data_size = avctx->channels * avctx->frame_size; | |
163 | ||
164 | if ((ret = ff_alloc_packet2(avctx, avpkt, ROQ_HEADER_SIZE + data_size)) < 0) | |
165 | return ret; | |
166 | out = avpkt->data; | |
167 | ||
168 | bytestream_put_byte(&out, stereo ? 0x21 : 0x20); | |
169 | bytestream_put_byte(&out, 0x10); | |
170 | bytestream_put_le32(&out, data_size); | |
171 | ||
172 | if (stereo) { | |
173 | bytestream_put_byte(&out, (context->lastSample[1])>>8); | |
174 | bytestream_put_byte(&out, (context->lastSample[0])>>8); | |
175 | } else | |
176 | bytestream_put_le16(&out, context->lastSample[0]); | |
177 | ||
178 | /* Write the actual samples */ | |
179 | for (i = 0; i < data_size; i++) | |
180 | *out++ = dpcm_predict(&context->lastSample[i & 1], *in++); | |
181 | ||
182 | avpkt->pts = context->input_frames <= 7 ? context->first_pts : frame->pts; | |
183 | avpkt->duration = data_size / avctx->channels; | |
184 | ||
185 | context->input_frames++; | |
186 | if (!in) | |
187 | context->input_frames = FFMAX(context->input_frames, 8); | |
188 | ||
189 | *got_packet_ptr = 1; | |
190 | return 0; | |
191 | } | |
192 | ||
193 | AVCodec ff_roq_dpcm_encoder = { | |
194 | .name = "roq_dpcm", | |
195 | .long_name = NULL_IF_CONFIG_SMALL("id RoQ DPCM"), | |
196 | .type = AVMEDIA_TYPE_AUDIO, | |
197 | .id = AV_CODEC_ID_ROQ_DPCM, | |
198 | .priv_data_size = sizeof(ROQDPCMContext), | |
199 | .init = roq_dpcm_encode_init, | |
200 | .encode2 = roq_dpcm_encode_frame, | |
201 | .close = roq_dpcm_encode_close, | |
202 | .capabilities = CODEC_CAP_DELAY, | |
203 | .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, | |
204 | AV_SAMPLE_FMT_NONE }, | |
205 | }; |