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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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✗✓ |
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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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✗✓ |
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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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✓✓ |
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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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✓✓ |
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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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}; |