aac5773f
 hucm
功能基本完成，接口待打磨
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/*
* Discworld II BMV audio decoder
* Copyright (c) 2011 Konstantin Shishkov
*
* 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 "libavutil/channel_layout.h"
#include "libavutil/common.h"
#include "avcodec.h"
#include "internal.h"
static const int bmv_aud_mults[16] = {
16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
};
static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
{
avctx->channels = 2;
avctx->channel_layout = AV_CH_LAYOUT_STEREO;
avctx->sample_fmt = AV_SAMPLE_FMT_S16;
return 0;
}
static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data,
int *got_frame_ptr, AVPacket *avpkt)
{
AVFrame *frame = data;
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
int blocks = 0, total_blocks, i;
int ret;
int16_t *output_samples;
int scale[2];
total_blocks = *buf++;
if (buf_size < total_blocks * 65 + 1) {
av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n",
total_blocks * 65 + 1, buf_size);
return AVERROR_INVALIDDATA;
}
/* get output buffer */
frame->nb_samples = total_blocks * 32;
if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
return ret;
output_samples = (int16_t *)frame->data[0];
for (blocks = 0; blocks < total_blocks; blocks++) {
uint8_t code = *buf++;
code = (code >> 1) | (code << 7);
scale[0] = bmv_aud_mults[code & 0xF];
scale[1] = bmv_aud_mults[code >> 4];
for (i = 0; i < 32; i++) {
*output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5);
*output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5);
}
}
*got_frame_ptr = 1;
return buf_size;
}
AVCodec ff_bmv_audio_decoder = {
.name = "bmv_audio",
.long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),
.type = AVMEDIA_TYPE_AUDIO,
.id = AV_CODEC_ID_BMV_AUDIO,
.init = bmv_aud_decode_init,
.decode = bmv_aud_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
};
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