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1 | Library: libffmpegFLAC | ||
2 | Imported: 2005-10-26 by Dave Chapman | ||
3 | |||
4 | This directory contains a FLAC decoder based on the flac.c (and a small | ||
5 | number of other files) from the ffmpeg project. | ||
6 | |||
7 | LICENSING INFORMATION | ||
8 | |||
9 | ffmpeg is licensed under the Lesser GNU General Public License and the | ||
10 | file flac.c is Copyright 2003 Alex Beregszaszi. | ||
11 | |||
12 | IMPORT DETAILS | ||
13 | |||
14 | The decoder is based on ffmpeg-cvs from 26 October 2005. | ||
15 | |||
16 | The file libavcodec/flac.c was renamed to decoder.c and all ffmpeg | ||
17 | related code was removed. It was also heavily modified to remove | ||
18 | debugging information and unused experiemental code. | ||
19 | |||
20 | It was also changed to provide output as 32-bit integers (with the | ||
21 | data left-shifted to 28 bit accuracy). The original flac.c provided | ||
22 | 16-bit output. | ||
23 | |||
24 | In order to minimise memory usage, a small number of hard-coded limits | ||
25 | are present in decoder.h - mainly limiting the supported blocksize | ||
26 | (number of samples in a frame) to 4608. This is the default value | ||
27 | used by the reference FLAC encoder at all standard compression | ||
28 | settings. | ||
29 | |||
30 | |||
31 | TESTING | ||
32 | |||
33 | A test program is contained in the file main.c and this should compile | ||
34 | in any Unix-like environment using the command "make -f Makefile.test". | ||
35 | |||
36 | Running "test file.flac" will decode the audio data to a WAV file | ||
37 | called "test.wav" in the current directory. This has been tested with | ||
38 | 16-bit and 24-bit mono and stereo FLAC files. | ||
39 | |||
40 | This can be used to test the accuracy of the decoder by comparing the | ||
41 | md5sum of the WAV file produced by this decoder with a WAV file | ||
42 | produced by the official libFLAC decoder. | ||
43 | |||
44 | This test program could be extended to perform an internal md5sum | ||
45 | calculation and comparing that against the md5sum stored in the FLAC | ||
46 | file's header. | ||