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/* |
* RoQ audio encoder |
* |
* Copyright (c) 2005 Eric Lasota |
* Based on RoQ specs (c)2001 Tim Ferguson |
* |
* This file is part of FFmpeg. |
* |
* FFmpeg is free software; you can redistribute it and/or |
* modify it under the terms of the GNU Lesser General Public |
* License as published by the Free Software Foundation; either |
* version 2.1 of the License, or (at your option) any later version. |
* |
* FFmpeg is distributed in the hope that it will be useful, |
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
* Lesser General Public License for more details. |
* |
* You should have received a copy of the GNU Lesser General Public |
* License along with FFmpeg; if not, write to the Free Software |
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
*/ |
|
#include "avcodec.h" |
#include "bytestream.h" |
#include "internal.h" |
#include "mathops.h" |
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#define ROQ_FRAME_SIZE 735 |
#define ROQ_HEADER_SIZE 8 |
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#define MAX_DPCM (127*127) |
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typedef struct ROQDPCMContext { |
short lastSample[2]; |
int input_frames; |
int buffered_samples; |
int16_t *frame_buffer; |
int64_t first_pts; |
} ROQDPCMContext; |
|
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static av_cold int roq_dpcm_encode_close(AVCodecContext *avctx) |
{ |
ROQDPCMContext *context = avctx->priv_data; |
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av_freep(&context->frame_buffer); |
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return 0; |
} |
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static av_cold int roq_dpcm_encode_init(AVCodecContext *avctx) |
{ |
ROQDPCMContext *context = avctx->priv_data; |
int ret; |
|
if (avctx->channels > 2) { |
av_log(avctx, AV_LOG_ERROR, "Audio must be mono or stereo\n"); |
return AVERROR(EINVAL); |
} |
if (avctx->sample_rate != 22050) { |
av_log(avctx, AV_LOG_ERROR, "Audio must be 22050 Hz\n"); |
return AVERROR(EINVAL); |
} |
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avctx->frame_size = ROQ_FRAME_SIZE; |
avctx->bit_rate = (ROQ_HEADER_SIZE + ROQ_FRAME_SIZE * avctx->channels) * |
(22050 / ROQ_FRAME_SIZE) * 8; |
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context->frame_buffer = av_malloc(8 * ROQ_FRAME_SIZE * avctx->channels * |
sizeof(*context->frame_buffer)); |
if (!context->frame_buffer) { |
ret = AVERROR(ENOMEM); |
goto error; |
} |
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context->lastSample[0] = context->lastSample[1] = 0; |
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return 0; |
error: |
roq_dpcm_encode_close(avctx); |
return ret; |
} |
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static unsigned char dpcm_predict(short *previous, short current) |
{ |
int diff; |
int negative; |
int result; |
int predicted; |
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diff = current - *previous; |
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negative = diff<0; |
diff = FFABS(diff); |
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if (diff >= MAX_DPCM) |
result = 127; |
else { |
result = ff_sqrt(diff); |
result += diff > result*result+result; |
} |
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/* See if this overflows */ |
retry: |
diff = result*result; |
if (negative) |
diff = -diff; |
predicted = *previous + diff; |
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/* If it overflows, back off a step */ |
if (predicted > 32767 || predicted < -32768) { |
result--; |
goto retry; |
} |
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/* Add the sign bit */ |
result |= negative << 7; //if (negative) result |= 128; |
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*previous = predicted; |
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return result; |
} |
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static int roq_dpcm_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, |
const AVFrame *frame, int *got_packet_ptr) |
{ |
int i, stereo, data_size, ret; |
const int16_t *in = frame ? (const int16_t *)frame->data[0] : NULL; |
uint8_t *out; |
ROQDPCMContext *context = avctx->priv_data; |
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stereo = (avctx->channels == 2); |
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if (!in && context->input_frames >= 8) |
return 0; |
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if (in && context->input_frames < 8) { |
memcpy(&context->frame_buffer[context->buffered_samples * avctx->channels], |
in, avctx->frame_size * avctx->channels * sizeof(*in)); |
context->buffered_samples += avctx->frame_size; |
if (context->input_frames == 0) |
context->first_pts = frame->pts; |
if (context->input_frames < 7) { |
context->input_frames++; |
return 0; |
} |
} |
if (context->input_frames < 8) |
in = context->frame_buffer; |
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if (stereo) { |
context->lastSample[0] &= 0xFF00; |
context->lastSample[1] &= 0xFF00; |
} |
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if (context->input_frames == 7) |
data_size = avctx->channels * context->buffered_samples; |
else |
data_size = avctx->channels * avctx->frame_size; |
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if ((ret = ff_alloc_packet2(avctx, avpkt, ROQ_HEADER_SIZE + data_size, 0)) < 0) |
return ret; |
out = avpkt->data; |
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bytestream_put_byte(&out, stereo ? 0x21 : 0x20); |
bytestream_put_byte(&out, 0x10); |
bytestream_put_le32(&out, data_size); |
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if (stereo) { |
bytestream_put_byte(&out, (context->lastSample[1])>>8); |
bytestream_put_byte(&out, (context->lastSample[0])>>8); |
} else |
bytestream_put_le16(&out, context->lastSample[0]); |
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/* Write the actual samples */ |
for (i = 0; i < data_size; i++) |
*out++ = dpcm_predict(&context->lastSample[i & 1], *in++); |
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avpkt->pts = context->input_frames <= 7 ? context->first_pts : frame->pts; |
avpkt->duration = data_size / avctx->channels; |
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context->input_frames++; |
if (!in) |
context->input_frames = FFMAX(context->input_frames, 8); |
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*got_packet_ptr = 1; |
return 0; |
} |
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AVCodec ff_roq_dpcm_encoder = { |
.name = "roq_dpcm", |
.long_name = NULL_IF_CONFIG_SMALL("id RoQ DPCM"), |
.type = AVMEDIA_TYPE_AUDIO, |
.id = AV_CODEC_ID_ROQ_DPCM, |
.priv_data_size = sizeof(ROQDPCMContext), |
.init = roq_dpcm_encode_init, |
.encode2 = roq_dpcm_encode_frame, |
.close = roq_dpcm_encode_close, |
.capabilities = AV_CODEC_CAP_DELAY, |
.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, |
AV_SAMPLE_FMT_NONE }, |
}; |