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