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 "codec_internal.h"
27 #include "internal.h"
28
29 static const int bmv_aud_mults[16] = {
30 16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
31 };
32
bmv_aud_decode_init(AVCodecContext *avctx)33 static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
34 {
35 av_channel_layout_uninit(&avctx->ch_layout);
36 avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
37 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
38
39 return 0;
40 }
41
bmv_aud_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt)42 static int bmv_aud_decode_frame(AVCodecContext *avctx, AVFrame *frame,
43 int *got_frame_ptr, AVPacket *avpkt)
44 {
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
81 const FFCodec ff_bmv_audio_decoder = {
82 .p.name = "bmv_audio",
83 .p.long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),
84 .p.type = AVMEDIA_TYPE_AUDIO,
85 .p.id = AV_CODEC_ID_BMV_AUDIO,
86 .init = bmv_aud_decode_init,
87 FF_CODEC_DECODE_CB(bmv_aud_decode_frame),
88 .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
89 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
90 };
91