blob: b1587ab3660e9e5157083abfde594461b79ae40c
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 | |
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 |
30 | }; |
31 | |
32 | static 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 | |
41 | static 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 | |
81 | AVCodec 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 = AV_CODEC_CAP_DR1, |
89 | }; |
90 |