| 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 | }; |