2 * Discworld II BMV audio decoder
3 * Copyright (c) 2011 Konstantin Shishkov
5 * This file is part of FFmpeg.
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.
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.
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
22 #include "libavutil/channel_layout.h"
23 #include "libavutil/common.h"
28 static const int bmv_aud_mults
[16] = {
29 16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
32 static av_cold
int bmv_aud_decode_init(AVCodecContext
*avctx
)
35 avctx
->channel_layout
= AV_CH_LAYOUT_STEREO
;
36 avctx
->sample_fmt
= AV_SAMPLE_FMT_S16
;
41 static int bmv_aud_decode_frame(AVCodecContext
*avctx
, void *data
,
42 int *got_frame_ptr
, AVPacket
*avpkt
)
44 AVFrame
*frame
= data
;
45 const uint8_t *buf
= avpkt
->data
;
46 int buf_size
= avpkt
->size
;
47 int blocks
= 0, total_blocks
, i
;
49 int16_t *output_samples
;
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
;
59 /* get output buffer */
60 frame
->nb_samples
= total_blocks
* 32;
61 if ((ret
= ff_get_buffer(avctx
, frame
, 0)) < 0)
63 output_samples
= (int16_t *)frame
->data
[0];
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);
81 AVCodec ff_bmv_audio_decoder
= {
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
,