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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 = CODEC_CAP_DR1, | |
89 | }; |