2 DK3 ADPCM Decoder for MPlayer
5 "This format number was used by Duck Corp. but not officially
6 registered with Microsoft"
8 This file is responsible for decoding audio data encoded with
9 Duck Corp's DK3 ADPCM algorithm. Details about the data format
11 http://www.pcisys.net/~melanson/codecs/
20 #include "ad_internal.h"
22 static ad_info_t info
=
24 "Duck Corp. DK3 ADPCM decoder",
31 LIBAD_EXTERN(dk3adpcm
)
33 #define DK3_ADPCM_PREAMBLE_SIZE 16
35 #define LE_16(x) (le2me_16(*(unsigned short *)(x)))
36 #define LE_32(x) (le2me_32(*(unsigned int *)(x)))
39 // clamp a number between 0 and 88
40 #define CLAMP_0_TO_88(x) if (x < 0) x = 0; else if (x > 88) x = 88;
41 // clamp a number within a signed 16-bit range
42 #define CLAMP_S16(x) if (x < -32768) x = -32768; \
43 else if (x > 32767) x = 32767;
44 // clamp a number above 16
45 #define CLAMP_ABOVE_16(x) if (x < 16) x = 16;
46 // sign extend a 16-bit value
47 #define SE_16BIT(x) if (x & 0x8000) x -= 0x10000;
48 // sign extend a 4-bit value
49 #define SE_4BIT(x) if (x & 0x8) x -= 0x10;
52 static int adpcm_step
[89] =
54 7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
55 19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
56 50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
57 130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
58 337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
59 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
60 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
61 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
62 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
65 static int adpcm_index
[16] =
67 -1, -1, -1, -1, 2, 4, 6, 8,
68 -1, -1, -1, -1, 2, 4, 6, 8
71 static int preinit(sh_audio_t
*sh_audio
)
73 sh_audio
->audio_out_minsize
= sh_audio
->wf
->nBlockAlign
* 6;
74 sh_audio
->ds
->ss_div
=
75 (sh_audio
->wf
->nBlockAlign
- DK3_ADPCM_PREAMBLE_SIZE
) * 8 / 3;
76 sh_audio
->audio_in_minsize
=
77 sh_audio
->ds
->ss_mul
= sh_audio
->wf
->nBlockAlign
;
81 static int init(sh_audio_t
*sh_audio
)
83 sh_audio
->channels
= sh_audio
->wf
->nChannels
;
84 sh_audio
->samplerate
= sh_audio
->wf
->nSamplesPerSec
;
86 (sh_audio
->ds
->ss_mul
* sh_audio
->samplerate
) / sh_audio
->ds
->ss_div
;
87 sh_audio
->samplesize
=2;
91 static void uninit(sh_audio_t
*sh_audio
)
95 static int control(sh_audio_t
*sh_audio
,int cmd
,void* arg
, ...)
97 if(cmd
==ADCTRL_SKIP_FRAME
){
98 demux_read_data(sh_audio
->ds
, sh_audio
->a_in_buffer
,sh_audio
->ds
->ss_mul
);
101 return CONTROL_UNKNOWN
;
104 #define DK3_GET_NEXT_NIBBLE() \
105 if (decode_top_nibble_next) \
107 nibble = (last_byte >> 4) & 0x0F; \
108 decode_top_nibble_next = 0; \
112 last_byte = input[in_ptr++]; \
113 nibble = last_byte & 0x0F; \
114 decode_top_nibble_next = 1; \
117 // note: This decoder assumes the format 0x62 data always comes in
119 static int dk3_adpcm_decode_block(unsigned short *output
, unsigned char *input
,
130 unsigned char last_byte
= 0;
131 unsigned char nibble
;
132 int decode_top_nibble_next
= 0;
134 // ADPCM work variables
140 sum_pred
= LE_16(&input
[10]);
141 diff_pred
= LE_16(&input
[12]);
144 diff_channel
= diff_pred
;
145 sum_index
= input
[14];
146 diff_index
= input
[15];
148 while (in_ptr
< block_size
)
149 // while (in_ptr < 2048)
151 // process the first predictor of the sum channel
152 DK3_GET_NEXT_NIBBLE();
154 step
= adpcm_step
[sum_index
];
160 if (delta
& 4) diff
+= step
;
161 if (delta
& 2) diff
+= step
>> 1;
162 if (delta
& 1) diff
+= step
>> 2;
171 sum_index
+= adpcm_index
[nibble
];
172 CLAMP_0_TO_88(sum_index
);
174 // process the diff channel predictor
175 DK3_GET_NEXT_NIBBLE();
177 step
= adpcm_step
[diff_index
];
183 if (delta
& 4) diff
+= step
;
184 if (delta
& 2) diff
+= step
>> 1;
185 if (delta
& 1) diff
+= step
>> 2;
192 CLAMP_S16(diff_pred
);
194 diff_index
+= adpcm_index
[nibble
];
195 CLAMP_0_TO_88(diff_index
);
197 // output the first pair of stereo PCM samples
198 diff_channel
= (diff_channel
+ diff_pred
) / 2;
199 output
[out_ptr
++] = sum_pred
+ diff_channel
;
200 output
[out_ptr
++] = sum_pred
- diff_channel
;
202 // process the second predictor of the sum channel
203 DK3_GET_NEXT_NIBBLE();
205 step
= adpcm_step
[sum_index
];
211 if (delta
& 4) diff
+= step
;
212 if (delta
& 2) diff
+= step
>> 1;
213 if (delta
& 1) diff
+= step
>> 2;
222 sum_index
+= adpcm_index
[nibble
];
223 CLAMP_0_TO_88(sum_index
);
225 // output the second pair of stereo PCM samples
226 output
[out_ptr
++] = sum_pred
+ diff_channel
;
227 output
[out_ptr
++] = sum_pred
- diff_channel
;
233 static int decode_audio(sh_audio_t
*sh_audio
,unsigned char *buf
,int minlen
,int maxlen
)
235 if (demux_read_data(sh_audio
->ds
, sh_audio
->a_in_buffer
,
236 sh_audio
->ds
->ss_mul
) !=
237 sh_audio
->ds
->ss_mul
)
240 return 2 * dk3_adpcm_decode_block(
241 (unsigned short*)buf
, sh_audio
->a_in_buffer
,
242 sh_audio
->wf
->nBlockAlign
);