3 demac - A Monkey's Audio decoder
7 Copyright (C) Dave Chapman 2007
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
27 This example is intended to demonstrate how the decoder can be used in
28 embedded devices - there is no usage of dynamic memory (i.e. no
29 malloc/free) and small buffer sizes are chosen to minimise both the
30 memory usage and decoding latency.
32 This implementation requires the following memory and supports decoding of all APE files up to 24-bit Stereo.
34 32768 - data from the input stream to be presented to the decoder in one contiguous chunk.
35 18432 - decoding buffer (left channel)
36 18432 - decoding buffer (right channel)
38 17408+5120+2240 - buffers used for filter histories (compression levels 2000-5000)
40 In addition, this example uses a static 27648 byte buffer as temporary
41 storage for outputting the data to a WAV file but that could be
42 avoided by writing the decoded data one sample at a time.
49 #include <sys/types.h>
64 #define BLOCKS_PER_LOOP 4608
65 #define MAX_CHANNELS 2
66 #define MAX_BYTESPERSAMPLE 3
68 #define INPUT_CHUNKSIZE (32*1024)
71 #define MIN(a,b) ((a) < (b) ? (a) : (b))
75 /* 4608*2*3 = 27648 bytes */
76 static unsigned char wavbuffer
[BLOCKS_PER_LOOP
*MAX_CHANNELS
*MAX_BYTESPERSAMPLE
];
78 /* 4608*4 = 18432 bytes per channel */
79 static int32_t decoded0
[BLOCKS_PER_LOOP
];
80 static int32_t decoded1
[BLOCKS_PER_LOOP
];
82 /* We assume that 32KB of compressed data is enough to extract up to
83 27648 bytes of decompressed data. */
85 static unsigned char inbuffer
[INPUT_CHUNKSIZE
];
87 int ape_decode(char* infile
, char* outfile
)
94 struct ape_ctx_t ape_ctx
;
106 fd
= open(infile
,O_RDONLY
|O_BINARY
);
107 if (fd
< 0) return -1;
109 /* Read the file headers to populate the ape_ctx struct */
110 if (ape_parseheader(fd
,&ape_ctx
) < 0) {
111 printf("Cannot read header\n");
116 if ((ape_ctx
.fileversion
< APE_MIN_VERSION
) || (ape_ctx
.fileversion
> APE_MAX_VERSION
)) {
117 printf("Unsupported file version - %.2f\n", ape_ctx
.fileversion
/1000.0);
122 //ape_dumpinfo(&ape_ctx);
124 printf("Decoding file - v%.2f, compression level %d\n",ape_ctx
.fileversion
/1000.0,ape_ctx
.compressiontype
);
126 /* Open the WAV file and write a canonical 44-byte WAV header
127 based on the audio format information in the ape_ctx struct.
129 NOTE: This example doesn't write the original WAV header and
130 tail data which are (optionally) stored in the APE file.
132 fdwav
= open_wav(&ape_ctx
,outfile
);
136 /* Initialise the buffer */
137 lseek(fd
, ape_ctx
.firstframe
, SEEK_SET
);
138 bytesinbuffer
= read(fd
, inbuffer
, INPUT_CHUNKSIZE
);
139 firstbyte
= 3; /* Take account of the little-endian 32-bit byte ordering */
141 /* The main decoding loop - we decode the frames a small chunk at a time */
142 while (currentframe
< ape_ctx
.totalframes
)
144 /* Calculate how many blocks there are in this frame */
145 if (currentframe
== (ape_ctx
.totalframes
- 1))
146 nblocks
= ape_ctx
.finalframeblocks
;
148 nblocks
= ape_ctx
.blocksperframe
;
150 ape_ctx
.currentframeblocks
= nblocks
;
152 /* Initialise the frame decoder */
153 init_frame_decoder(&ape_ctx
, inbuffer
, &firstbyte
, &bytesconsumed
);
156 memmove(inbuffer
,inbuffer
+ bytesconsumed
, bytesinbuffer
- bytesconsumed
);
157 bytesinbuffer
-= bytesconsumed
;
159 n
= read(fd
, inbuffer
+ bytesinbuffer
, INPUT_CHUNKSIZE
- bytesinbuffer
);
163 frame_crc
= ape_initcrc();
166 /* Decode the frame a chunk at a time */
169 blockstodecode
= MIN(BLOCKS_PER_LOOP
, nblocks
);
171 if ((res
= decode_chunk(&ape_ctx
, inbuffer
, &firstbyte
,
174 blockstodecode
)) < 0)
176 /* Frame decoding error, abort */
181 /* Convert the output samples to WAV format and write to output file */
183 if (ape_ctx
.bps
== 16) {
184 for (i
= 0 ; i
< blockstodecode
; i
++)
186 sample16
= decoded0
[i
];
187 *(p
++) = sample16
& 0xff;
188 *(p
++) = (sample16
&0xff00) >> 8;
190 if (ape_ctx
.channels
== 2) {
191 sample16
= decoded1
[i
];
192 *(p
++) = sample16
& 0xff;
193 *(p
++) = (sample16
&0xff00) >> 8;
196 } else if (ape_ctx
.bps
== 24) {
197 for (i
= 0 ; i
< blockstodecode
; i
++)
199 sample32
= decoded0
[i
];
200 *(p
++) = sample32
& 0xff;
201 *(p
++) = (sample32
&0xff00) >> 8;
202 *(p
++) = (sample32
&0xff0000) >> 16;
204 if (ape_ctx
.channels
== 2) {
205 sample32
= decoded1
[i
];
206 *(p
++) = sample32
& 0xff;
207 *(p
++) = (sample32
&0xff00) >> 8;
208 *(p
++) = (sample32
&0xff0000) >> 16;
214 frame_crc
= ape_updatecrc(wavbuffer
, p
- wavbuffer
, frame_crc
);
216 write(fdwav
,wavbuffer
,p
- wavbuffer
);
218 /* Update the buffer */
219 memmove(inbuffer
,inbuffer
+ bytesconsumed
, bytesinbuffer
- bytesconsumed
);
220 bytesinbuffer
-= bytesconsumed
;
222 n
= read(fd
, inbuffer
+ bytesinbuffer
, INPUT_CHUNKSIZE
- bytesinbuffer
);
225 /* Decrement the block count */
226 nblocks
-= blockstodecode
;
230 frame_crc
= ape_finishcrc(frame_crc
);
232 if (ape_ctx
.CRC
!= frame_crc
)
234 fprintf(stderr
,"CRC error in frame %d\n",currentframe
);
251 int main(int argc
, char* argv
[])
256 fprintf(stderr
,"Usage: demac infile.ape outfile.wav\n");
260 res
= ape_decode(argv
[1], argv
[2]);
264 fprintf(stderr
,"DECODING ERROR %d, ABORTING\n", res
);
268 fprintf(stderr
,"DECODED OK - NO CRC ERRORS.\n");