4 * Copyright (c) 2005 Eric Lasota
5 * Based on RoQ specs (c)2001 Tim Ferguson
7 * This file is part of Libav.
9 * Libav 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.
14 * Libav 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.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with Libav; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include "libavutil/intmath.h"
26 #include "bytestream.h"
28 #define ROQ_FRAME_SIZE 735
29 #define ROQ_HEADER_SIZE 8
31 #define MAX_DPCM (127*127)
39 int16_t *frame_buffer;
43 static av_cold int roq_dpcm_encode_close(AVCodecContext *avctx)
45 ROQDPCMContext *context = avctx->priv_data;
47 av_freep(&avctx->coded_frame);
48 av_freep(&context->frame_buffer);
53 static av_cold int roq_dpcm_encode_init(AVCodecContext *avctx)
55 ROQDPCMContext *context = avctx->priv_data;
58 if (avctx->channels > 2) {
59 av_log(avctx, AV_LOG_ERROR, "Audio must be mono or stereo\n");
60 return AVERROR(EINVAL);
62 if (avctx->sample_rate != 22050) {
63 av_log(avctx, AV_LOG_ERROR, "Audio must be 22050 Hz\n");
64 return AVERROR(EINVAL);
67 avctx->frame_size = ROQ_FRAME_SIZE;
68 avctx->bit_rate = (ROQ_HEADER_SIZE + ROQ_FRAME_SIZE * avctx->channels) *
69 (22050 / ROQ_FRAME_SIZE) * 8;
71 context->frame_buffer = av_malloc(8 * ROQ_FRAME_SIZE * avctx->channels *
72 sizeof(*context->frame_buffer));
73 if (!context->frame_buffer) {
74 ret = AVERROR(ENOMEM);
78 context->lastSample[0] = context->lastSample[1] = 0;
80 avctx->coded_frame= avcodec_alloc_frame();
81 if (!avctx->coded_frame) {
82 ret = AVERROR(ENOMEM);
88 roq_dpcm_encode_close(avctx);
92 static unsigned char dpcm_predict(short *previous, short current)
99 diff = current - *previous;
104 if (diff >= MAX_DPCM)
107 result = ff_sqrt(diff);
108 result += diff > result*result+result;
111 /* See if this overflows */
113 diff = result*result;
116 predicted = *previous + diff;
118 /* If it overflows, back off a step */
119 if (predicted > 32767 || predicted < -32768) {
124 /* Add the sign bit */
125 result |= negative << 7; //if (negative) result |= 128;
127 *previous = predicted;
132 static int roq_dpcm_encode_frame(AVCodecContext *avctx,
133 unsigned char *frame, int buf_size, void *data)
135 int i, stereo, data_size;
136 const int16_t *in = data;
137 uint8_t *out = frame;
138 ROQDPCMContext *context = avctx->priv_data;
140 stereo = (avctx->channels == 2);
142 if (!data && context->input_frames >= 8)
145 if (data && context->input_frames < 8) {
146 memcpy(&context->frame_buffer[context->buffered_samples * avctx->channels],
147 in, avctx->frame_size * avctx->channels * sizeof(*in));
148 context->buffered_samples += avctx->frame_size;
149 if (context->input_frames < 7) {
150 context->input_frames++;
153 in = context->frame_buffer;
157 context->lastSample[0] &= 0xFF00;
158 context->lastSample[1] &= 0xFF00;
161 if (context->input_frames == 7 || !data)
162 data_size = avctx->channels * context->buffered_samples;
164 data_size = avctx->channels * avctx->frame_size;
166 if (buf_size < ROQ_HEADER_SIZE + data_size) {
167 av_log(avctx, AV_LOG_ERROR, "output buffer is too small\n");
168 return AVERROR(EINVAL);
171 bytestream_put_byte(&out, stereo ? 0x21 : 0x20);
172 bytestream_put_byte(&out, 0x10);
173 bytestream_put_le32(&out, data_size);
176 bytestream_put_byte(&out, (context->lastSample[1])>>8);
177 bytestream_put_byte(&out, (context->lastSample[0])>>8);
179 bytestream_put_le16(&out, context->lastSample[0]);
181 /* Write the actual samples */
182 for (i = 0; i < data_size; i++)
183 *out++ = dpcm_predict(&context->lastSample[i & 1], *in++);
185 context->input_frames++;
187 context->input_frames = FFMAX(context->input_frames, 8);
189 /* Return the result size */
190 return ROQ_HEADER_SIZE + data_size;
193 AVCodec ff_roq_dpcm_encoder = {
195 .type = AVMEDIA_TYPE_AUDIO,
196 .id = CODEC_ID_ROQ_DPCM,
197 .priv_data_size = sizeof(ROQDPCMContext),
198 .init = roq_dpcm_encode_init,
199 .encode = roq_dpcm_encode_frame,
200 .close = roq_dpcm_encode_close,
201 .capabilities = CODEC_CAP_DELAY,
202 .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
203 .long_name = NULL_IF_CONFIG_SMALL("id RoQ DPCM"),