1/*
2 * Sierra VMD audio decoder
3 * Copyright (C) 2004 the ffmpeg project
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/**
23 * @file
24 * Sierra VMD audio decoder
25 * by Vladimir "VAG" Gneushev (vagsoft at mail.ru)
26 * for more information on the Sierra VMD format, visit:
27 *   http://www.pcisys.net/~melanson/codecs/
28 *
29 * The audio decoder, expects each encoded data
30 * chunk to be prepended with the appropriate 16-byte frame information
31 * record from the VMD file. It does not require the 0x330-byte VMD file
32 * header, but it does need the audio setup parameters passed in through
33 * normal libavcodec API means.
34 */
35
36#include <string.h>
37
38#include "libavutil/avassert.h"
39#include "libavutil/channel_layout.h"
40#include "libavutil/common.h"
41#include "libavutil/intreadwrite.h"
42
43#include "avcodec.h"
44#include "internal.h"
45
46#define BLOCK_TYPE_AUDIO    1
47#define BLOCK_TYPE_INITIAL  2
48#define BLOCK_TYPE_SILENCE  3
49
50typedef struct VmdAudioContext {
51    int out_bps;
52    int chunk_size;
53} VmdAudioContext;
54
55static const uint16_t vmdaudio_table[128] = {
56    0x000, 0x008, 0x010, 0x020, 0x030, 0x040, 0x050, 0x060, 0x070, 0x080,
57    0x090, 0x0A0, 0x0B0, 0x0C0, 0x0D0, 0x0E0, 0x0F0, 0x100, 0x110, 0x120,
58    0x130, 0x140, 0x150, 0x160, 0x170, 0x180, 0x190, 0x1A0, 0x1B0, 0x1C0,
59    0x1D0, 0x1E0, 0x1F0, 0x200, 0x208, 0x210, 0x218, 0x220, 0x228, 0x230,
60    0x238, 0x240, 0x248, 0x250, 0x258, 0x260, 0x268, 0x270, 0x278, 0x280,
61    0x288, 0x290, 0x298, 0x2A0, 0x2A8, 0x2B0, 0x2B8, 0x2C0, 0x2C8, 0x2D0,
62    0x2D8, 0x2E0, 0x2E8, 0x2F0, 0x2F8, 0x300, 0x308, 0x310, 0x318, 0x320,
63    0x328, 0x330, 0x338, 0x340, 0x348, 0x350, 0x358, 0x360, 0x368, 0x370,
64    0x378, 0x380, 0x388, 0x390, 0x398, 0x3A0, 0x3A8, 0x3B0, 0x3B8, 0x3C0,
65    0x3C8, 0x3D0, 0x3D8, 0x3E0, 0x3E8, 0x3F0, 0x3F8, 0x400, 0x440, 0x480,
66    0x4C0, 0x500, 0x540, 0x580, 0x5C0, 0x600, 0x640, 0x680, 0x6C0, 0x700,
67    0x740, 0x780, 0x7C0, 0x800, 0x900, 0xA00, 0xB00, 0xC00, 0xD00, 0xE00,
68    0xF00, 0x1000, 0x1400, 0x1800, 0x1C00, 0x2000, 0x3000, 0x4000
69};
70
71static av_cold int vmdaudio_decode_init(AVCodecContext *avctx)
72{
73    VmdAudioContext *s = avctx->priv_data;
74
75    if (avctx->channels < 1 || avctx->channels > 2) {
76        av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
77        return AVERROR(EINVAL);
78    }
79    if (avctx->block_align < 1 || avctx->block_align % avctx->channels) {
80        av_log(avctx, AV_LOG_ERROR, "invalid block align\n");
81        return AVERROR(EINVAL);
82    }
83
84    avctx->channel_layout = avctx->channels == 1 ? AV_CH_LAYOUT_MONO :
85                                                   AV_CH_LAYOUT_STEREO;
86
87    if (avctx->bits_per_coded_sample == 16)
88        avctx->sample_fmt = AV_SAMPLE_FMT_S16;
89    else
90        avctx->sample_fmt = AV_SAMPLE_FMT_U8;
91    s->out_bps = av_get_bytes_per_sample(avctx->sample_fmt);
92
93    s->chunk_size = avctx->block_align + avctx->channels * (s->out_bps == 2);
94
95    av_log(avctx, AV_LOG_DEBUG, "%d channels, %d bits/sample, "
96           "block align = %d, sample rate = %d\n",
97           avctx->channels, avctx->bits_per_coded_sample, avctx->block_align,
98           avctx->sample_rate);
99
100    return 0;
101}
102
103static void decode_audio_s16(int16_t *out, const uint8_t *buf, int buf_size,
104                             int channels)
105{
106    int ch;
107    const uint8_t *buf_end = buf + buf_size;
108    int predictor[2];
109    int st = channels - 1;
110
111    /* decode initial raw sample */
112    for (ch = 0; ch < channels; ch++) {
113        predictor[ch] = (int16_t)AV_RL16(buf);
114        buf += 2;
115        *out++ = predictor[ch];
116    }
117
118    /* decode DPCM samples */
119    ch = 0;
120    while (buf < buf_end) {
121        uint8_t b = *buf++;
122        if (b & 0x80)
123            predictor[ch] -= vmdaudio_table[b & 0x7F];
124        else
125            predictor[ch] += vmdaudio_table[b];
126        predictor[ch] = av_clip_int16(predictor[ch]);
127        *out++ = predictor[ch];
128        ch ^= st;
129    }
130}
131
132static int vmdaudio_decode_frame(AVCodecContext *avctx, void *data,
133                                 int *got_frame_ptr, AVPacket *avpkt)
134{
135    AVFrame *frame     = data;
136    const uint8_t *buf = avpkt->data;
137    const uint8_t *buf_end;
138    int buf_size = avpkt->size;
139    VmdAudioContext *s = avctx->priv_data;
140    int block_type, silent_chunks, audio_chunks;
141    int ret;
142    uint8_t *output_samples_u8;
143    int16_t *output_samples_s16;
144
145    if (buf_size < 16) {
146        av_log(avctx, AV_LOG_WARNING, "skipping small junk packet\n");
147        *got_frame_ptr = 0;
148        return buf_size;
149    }
150
151    block_type = buf[6];
152    if (block_type < BLOCK_TYPE_AUDIO || block_type > BLOCK_TYPE_SILENCE) {
153        av_log(avctx, AV_LOG_ERROR, "unknown block type: %d\n", block_type);
154        return AVERROR(EINVAL);
155    }
156    buf      += 16;
157    buf_size -= 16;
158
159    /* get number of silent chunks */
160    silent_chunks = 0;
161    if (block_type == BLOCK_TYPE_INITIAL) {
162        uint32_t flags;
163        if (buf_size < 4) {
164            av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
165            return AVERROR(EINVAL);
166        }
167        flags         = AV_RB32(buf);
168        silent_chunks = av_popcount(flags);
169        buf      += 4;
170        buf_size -= 4;
171    } else if (block_type == BLOCK_TYPE_SILENCE) {
172        silent_chunks = 1;
173        buf_size = 0; // should already be zero but set it just to be sure
174    }
175
176    /* ensure output buffer is large enough */
177    audio_chunks = buf_size / s->chunk_size;
178
179    /* drop incomplete chunks */
180    buf_size     = audio_chunks * s->chunk_size;
181
182    /* get output buffer */
183    frame->nb_samples = ((silent_chunks + audio_chunks) * avctx->block_align) /
184                        avctx->channels;
185    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
186        return ret;
187    output_samples_u8  =            frame->data[0];
188    output_samples_s16 = (int16_t *)frame->data[0];
189
190    /* decode silent chunks */
191    if (silent_chunks > 0) {
192        int silent_size = avctx->block_align * silent_chunks;
193        av_assert0(avctx->block_align * silent_chunks <= frame->nb_samples * avctx->channels);
194
195        if (s->out_bps == 2) {
196            memset(output_samples_s16, 0x00, silent_size * 2);
197            output_samples_s16 += silent_size;
198        } else {
199            memset(output_samples_u8,  0x80, silent_size);
200            output_samples_u8 += silent_size;
201        }
202    }
203
204    /* decode audio chunks */
205    if (audio_chunks > 0) {
206        buf_end = buf + buf_size;
207        av_assert0((buf_size & (avctx->channels > 1)) == 0);
208        while (buf_end - buf >= s->chunk_size) {
209            if (s->out_bps == 2) {
210                decode_audio_s16(output_samples_s16, buf, s->chunk_size,
211                                 avctx->channels);
212                output_samples_s16 += avctx->block_align;
213            } else {
214                memcpy(output_samples_u8, buf, s->chunk_size);
215                output_samples_u8  += avctx->block_align;
216            }
217            buf += s->chunk_size;
218        }
219    }
220
221    *got_frame_ptr = 1;
222
223    return avpkt->size;
224}
225
226AVCodec ff_vmdaudio_decoder = {
227    .name           = "vmdaudio",
228    .long_name      = NULL_IF_CONFIG_SMALL("Sierra VMD audio"),
229    .type           = AVMEDIA_TYPE_AUDIO,
230    .id             = AV_CODEC_ID_VMDAUDIO,
231    .priv_data_size = sizeof(VmdAudioContext),
232    .init           = vmdaudio_decode_init,
233    .decode         = vmdaudio_decode_frame,
234    .capabilities   = CODEC_CAP_DR1,
235};
236