1/* 2 * Discworld II BMV audio decoder 3 * Copyright (c) 2011 Konstantin Shishkov 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * FFmpeg is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with FFmpeg; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22#include "libavutil/channel_layout.h" 23#include "libavutil/common.h" 24 25#include "avcodec.h" 26#include "internal.h" 27 28static const int bmv_aud_mults[16] = { 29 16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32 30}; 31 32static av_cold int bmv_aud_decode_init(AVCodecContext *avctx) 33{ 34 avctx->channels = 2; 35 avctx->channel_layout = AV_CH_LAYOUT_STEREO; 36 avctx->sample_fmt = AV_SAMPLE_FMT_S16; 37 38 return 0; 39} 40 41static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data, 42 int *got_frame_ptr, AVPacket *avpkt) 43{ 44 AVFrame *frame = data; 45 const uint8_t *buf = avpkt->data; 46 int buf_size = avpkt->size; 47 int blocks = 0, total_blocks, i; 48 int ret; 49 int16_t *output_samples; 50 int scale[2]; 51 52 total_blocks = *buf++; 53 if (buf_size < total_blocks * 65 + 1) { 54 av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n", 55 total_blocks * 65 + 1, buf_size); 56 return AVERROR_INVALIDDATA; 57 } 58 59 /* get output buffer */ 60 frame->nb_samples = total_blocks * 32; 61 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) 62 return ret; 63 output_samples = (int16_t *)frame->data[0]; 64 65 for (blocks = 0; blocks < total_blocks; blocks++) { 66 uint8_t code = *buf++; 67 code = (code >> 1) | (code << 7); 68 scale[0] = bmv_aud_mults[code & 0xF]; 69 scale[1] = bmv_aud_mults[code >> 4]; 70 for (i = 0; i < 32; i++) { 71 *output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5); 72 *output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5); 73 } 74 } 75 76 *got_frame_ptr = 1; 77 78 return buf_size; 79} 80 81AVCodec ff_bmv_audio_decoder = { 82 .name = "bmv_audio", 83 .long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"), 84 .type = AVMEDIA_TYPE_AUDIO, 85 .id = AV_CODEC_ID_BMV_AUDIO, 86 .init = bmv_aud_decode_init, 87 .decode = bmv_aud_decode_frame, 88 .capabilities = CODEC_CAP_DR1, 89}; 90