90 lines
2.8 KiB
C
90 lines
2.8 KiB
C
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/*
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* Discworld II BMV audio decoder
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* Copyright (c) 2011 Konstantin Shishkov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/channel_layout.h"
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#include "libavutil/common.h"
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#include "avcodec.h"
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#include "internal.h"
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static const int bmv_aud_mults[16] = {
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16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
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};
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static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
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{
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avctx->channels = 2;
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avctx->channel_layout = AV_CH_LAYOUT_STEREO;
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avctx->sample_fmt = AV_SAMPLE_FMT_S16;
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return 0;
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}
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static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data,
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int *got_frame_ptr, AVPacket *avpkt)
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{
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AVFrame *frame = data;
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const uint8_t *buf = avpkt->data;
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int buf_size = avpkt->size;
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int blocks = 0, total_blocks, i;
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int ret;
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int16_t *output_samples;
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int scale[2];
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total_blocks = *buf++;
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if (buf_size < total_blocks * 65 + 1) {
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av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n",
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total_blocks * 65 + 1, buf_size);
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return AVERROR_INVALIDDATA;
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}
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/* get output buffer */
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frame->nb_samples = total_blocks * 32;
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if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
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return ret;
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output_samples = (int16_t *)frame->data[0];
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for (blocks = 0; blocks < total_blocks; blocks++) {
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uint8_t code = *buf++;
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code = (code >> 1) | (code << 7);
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scale[0] = bmv_aud_mults[code & 0xF];
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scale[1] = bmv_aud_mults[code >> 4];
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for (i = 0; i < 32; i++) {
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*output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5);
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*output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5);
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}
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}
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*got_frame_ptr = 1;
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return buf_size;
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}
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AVCodec ff_bmv_audio_decoder = {
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.name = "bmv_audio",
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.long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),
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.type = AVMEDIA_TYPE_AUDIO,
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.id = AV_CODEC_ID_BMV_AUDIO,
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.init = bmv_aud_decode_init,
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.decode = bmv_aud_decode_frame,
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.capabilities = AV_CODEC_CAP_DR1,
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};
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