1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2000-2009 Josh Coalson
3 * Copyright (C) 2011-2013 Xiph.Org Foundation
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
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13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
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17 * contributors may be used to endorse or promote products derived from
18 * this software without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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43 #include "stream_decoder.h"
44 #include "stream_encoder.h"
48 * \section intro Introduction
50 * This is the documentation for the FLAC C and C++ APIs. It is
51 * highly interconnected; this introduction should give you a top
52 * level idea of the structure and how to find the information you
53 * need. As a prerequisite you should have at least a basic
54 * knowledge of the FLAC format, documented
55 * <A HREF="../format.html">here</A>.
57 * \section c_api FLAC C API
59 * The FLAC C API is the interface to libFLAC, a set of structures
60 * describing the components of FLAC streams, and functions for
61 * encoding and decoding streams, as well as manipulating FLAC
62 * metadata in files. The public include files will be installed
63 * in your include area (for example /usr/include/FLAC/...).
65 * By writing a little code and linking against libFLAC, it is
66 * relatively easy to add FLAC support to another program. The
67 * library is licensed under <A HREF="../license.html">Xiph's BSD license</A>.
68 * Complete source code of libFLAC as well as the command-line
69 * encoder and plugins is available and is a useful source of
72 * Aside from encoders and decoders, libFLAC provides a powerful
73 * metadata interface for manipulating metadata in FLAC files. It
74 * allows the user to add, delete, and modify FLAC metadata blocks
75 * and it can automatically take advantage of PADDING blocks to avoid
76 * rewriting the entire FLAC file when changing the size of the
79 * libFLAC usually only requires the standard C library and C math
80 * library. In particular, threading is not used so there is no
81 * dependency on a thread library. However, libFLAC does not use
82 * global variables and should be thread-safe.
84 * libFLAC also supports encoding to and decoding from Ogg FLAC.
85 * However the metadata editing interfaces currently have limited
86 * read-only support for Ogg FLAC files.
88 * \section cpp_api FLAC C++ API
90 * The FLAC C++ API is a set of classes that encapsulate the
91 * structures and functions in libFLAC. They provide slightly more
92 * functionality with respect to metadata but are otherwise
93 * equivalent. For the most part, they share the same usage as
94 * their counterparts in libFLAC, and the FLAC C API documentation
95 * can be used as a supplement. The public include files
96 * for the C++ API will be installed in your include area (for
97 * example /usr/include/FLAC++/...).
99 * libFLAC++ is also licensed under
100 * <A HREF="../license.html">Xiph's BSD license</A>.
102 * \section getting_started Getting Started
104 * A good starting point for learning the API is to browse through
105 * the <A HREF="modules.html">modules</A>. Modules are logical
106 * groupings of related functions or classes, which correspond roughly
107 * to header files or sections of header files. Each module includes a
108 * detailed description of the general usage of its functions or
111 * From there you can go on to look at the documentation of
112 * individual functions. You can see different views of the individual
113 * functions through the links in top bar across this page.
115 * If you prefer a more hands-on approach, you can jump right to some
116 * <A HREF="../documentation_example_code.html">example code</A>.
118 * \section porting_guide Porting Guide
120 * Starting with FLAC 1.1.3 a \link porting Porting Guide \endlink
121 * has been introduced which gives detailed instructions on how to
122 * port your code to newer versions of FLAC.
124 * \section embedded_developers Embedded Developers
126 * libFLAC has grown larger over time as more functionality has been
127 * included, but much of it may be unnecessary for a particular embedded
128 * implementation. Unused parts may be pruned by some simple editing of
129 * src/libFLAC/Makefile.am. In general, the decoders, encoders, and
130 * metadata interface are all independent from each other.
132 * It is easiest to just describe the dependencies:
134 * - All modules depend on the \link flac_format Format \endlink module.
135 * - The decoders and encoders depend on the bitbuffer.
136 * - The decoder is independent of the encoder. The encoder uses the
137 * decoder because of the verify feature, but this can be removed if
139 * - Parts of the metadata interface require the stream decoder (but not
141 * - Ogg support is selectable through the compile time macro
144 * For example, if your application only requires the stream decoder, no
145 * encoder, and no metadata interface, you can remove the stream encoder
146 * and the metadata interface, which will greatly reduce the size of the
149 * Also, there are several places in the libFLAC code with comments marked
150 * with "OPT:" where a #define can be changed to enable code that might be
151 * faster on a specific platform. Experimenting with these can yield faster
155 /** \defgroup porting Porting Guide for New Versions
157 * This module describes differences in the library interfaces from
158 * version to version. It assists in the porting of code that uses
159 * the libraries to newer versions of FLAC.
161 * One simple facility for making porting easier that has been added
162 * in FLAC 1.1.3 is a set of \c #defines in \c export.h of each
163 * library's includes (e.g. \c include/FLAC/export.h). The
164 * \c #defines mirror the libraries'
165 * <A HREF="http://www.gnu.org/software/libtool/manual/libtool.html#Libtool-versioning">libtool version numbers</A>,
166 * e.g. in libFLAC there are \c FLAC_API_VERSION_CURRENT,
167 * \c FLAC_API_VERSION_REVISION, and \c FLAC_API_VERSION_AGE.
168 * These can be used to support multiple versions of an API during the
169 * transition phase, e.g.
172 * #if !defined(FLAC_API_VERSION_CURRENT) || FLAC_API_VERSION_CURRENT <= 7
179 * The the source will work for multiple versions and the legacy code can
180 * easily be removed when the transition is complete.
182 * Another available symbol is FLAC_API_SUPPORTS_OGG_FLAC (defined in
183 * include/FLAC/export.h), which can be used to determine whether or not
184 * the library has been compiled with support for Ogg FLAC. This is
185 * simpler than trying to call an Ogg init function and catching the
189 /** \defgroup porting_1_1_2_to_1_1_3 Porting from FLAC 1.1.2 to 1.1.3
193 * This module describes porting from FLAC 1.1.2 to FLAC 1.1.3.
195 * The main change between the APIs in 1.1.2 and 1.1.3 is that they have
196 * been simplified. First, libOggFLAC has been merged into libFLAC and
197 * libOggFLAC++ has been merged into libFLAC++. Second, both the three
198 * decoding layers and three encoding layers have been merged into a
199 * single stream decoder and stream encoder. That is, the functionality
200 * of FLAC__SeekableStreamDecoder and FLAC__FileDecoder has been merged
201 * into FLAC__StreamDecoder, and FLAC__SeekableStreamEncoder and
202 * FLAC__FileEncoder into FLAC__StreamEncoder. Only the
203 * FLAC__StreamDecoder and FLAC__StreamEncoder remain. What this means
204 * is there is now a single API that can be used to encode or decode
205 * streams to/from native FLAC or Ogg FLAC and the single API can work
206 * on both seekable and non-seekable streams.
208 * Instead of creating an encoder or decoder of a certain layer, now the
209 * client will always create a FLAC__StreamEncoder or
210 * FLAC__StreamDecoder. The old layers are now differentiated by the
211 * initialization function. For example, for the decoder,
212 * FLAC__stream_decoder_init() has been replaced by
213 * FLAC__stream_decoder_init_stream(). This init function takes
214 * callbacks for the I/O, and the seeking callbacks are optional. This
215 * allows the client to use the same object for seekable and
216 * non-seekable streams. For decoding a FLAC file directly, the client
217 * can use FLAC__stream_decoder_init_file() and pass just a filename
218 * and fewer callbacks; most of the other callbacks are supplied
219 * internally. For situations where fopen()ing by filename is not
220 * possible (e.g. Unicode filenames on Windows) the client can instead
221 * open the file itself and supply the FILE* to
222 * FLAC__stream_decoder_init_FILE(). The init functions now returns a
223 * FLAC__StreamDecoderInitStatus instead of FLAC__StreamDecoderState.
224 * Since the callbacks and client data are now passed to the init
225 * function, the FLAC__stream_decoder_set_*_callback() functions and
226 * FLAC__stream_decoder_set_client_data() are no longer needed. The
227 * rest of the calls to the decoder are the same as before.
229 * There are counterpart init functions for Ogg FLAC, e.g.
230 * FLAC__stream_decoder_init_ogg_stream(). All the rest of the calls
231 * and callbacks are the same as for native FLAC.
233 * As an example, in FLAC 1.1.2 a seekable stream decoder would have
234 * been set up like so:
237 * FLAC__SeekableStreamDecoder *decoder = FLAC__seekable_stream_decoder_new();
238 * if(decoder == NULL) do_something;
239 * FLAC__seekable_stream_decoder_set_md5_checking(decoder, true);
240 * [... other settings ...]
241 * FLAC__seekable_stream_decoder_set_read_callback(decoder, my_read_callback);
242 * FLAC__seekable_stream_decoder_set_seek_callback(decoder, my_seek_callback);
243 * FLAC__seekable_stream_decoder_set_tell_callback(decoder, my_tell_callback);
244 * FLAC__seekable_stream_decoder_set_length_callback(decoder, my_length_callback);
245 * FLAC__seekable_stream_decoder_set_eof_callback(decoder, my_eof_callback);
246 * FLAC__seekable_stream_decoder_set_write_callback(decoder, my_write_callback);
247 * FLAC__seekable_stream_decoder_set_metadata_callback(decoder, my_metadata_callback);
248 * FLAC__seekable_stream_decoder_set_error_callback(decoder, my_error_callback);
249 * FLAC__seekable_stream_decoder_set_client_data(decoder, my_client_data);
250 * if(FLAC__seekable_stream_decoder_init(decoder) != FLAC__SEEKABLE_STREAM_DECODER_OK) do_something;
253 * In FLAC 1.1.3 it is like this:
256 * FLAC__StreamDecoder *decoder = FLAC__stream_decoder_new();
257 * if(decoder == NULL) do_something;
258 * FLAC__stream_decoder_set_md5_checking(decoder, true);
259 * [... other settings ...]
260 * if(FLAC__stream_decoder_init_stream(
263 * my_seek_callback, // or NULL
264 * my_tell_callback, // or NULL
265 * my_length_callback, // or NULL
266 * my_eof_callback, // or NULL
268 * my_metadata_callback, // or NULL
271 * ) != FLAC__STREAM_DECODER_INIT_STATUS_OK) do_something;
278 * FILE *file = fopen("somefile.flac","rb");
279 * if(file == NULL) do_somthing;
280 * if(FLAC__stream_decoder_init_FILE(
284 * my_metadata_callback, // or NULL
287 * ) != FLAC__STREAM_DECODER_INIT_STATUS_OK) do_something;
294 * if(FLAC__stream_decoder_init_file(
298 * my_metadata_callback, // or NULL
301 * ) != FLAC__STREAM_DECODER_INIT_STATUS_OK) do_something;
304 * Another small change to the decoder is in how it handles unparseable
305 * streams. Before, when the decoder found an unparseable stream
306 * (reserved for when the decoder encounters a stream from a future
307 * encoder that it can't parse), it changed the state to
308 * \c FLAC__STREAM_DECODER_UNPARSEABLE_STREAM. Now the decoder instead
309 * drops sync and calls the error callback with a new error code
310 * \c FLAC__STREAM_DECODER_ERROR_STATUS_UNPARSEABLE_STREAM. This is
311 * more robust. If your error callback does not discriminate on the the
312 * error state, your code does not need to be changed.
314 * The encoder now has a new setting:
315 * FLAC__stream_encoder_set_apodization(). This is for setting the
316 * method used to window the data before LPC analysis. You only need to
317 * add a call to this function if the default is not suitable. There
318 * are also two new convenience functions that may be useful:
319 * FLAC__metadata_object_cuesheet_calculate_cddb_id() and
320 * FLAC__metadata_get_cuesheet().
322 * The \a bytes parameter to FLAC__StreamDecoderReadCallback,
323 * FLAC__StreamEncoderReadCallback, and FLAC__StreamEncoderWriteCallback
324 * is now \c size_t instead of \c unsigned.
327 /** \defgroup porting_1_1_3_to_1_1_4 Porting from FLAC 1.1.3 to 1.1.4
331 * This module describes porting from FLAC 1.1.3 to FLAC 1.1.4.
333 * There were no changes to any of the interfaces from 1.1.3 to 1.1.4.
334 * There was a slight change in the implementation of
335 * FLAC__stream_encoder_set_metadata(); the function now makes a copy
336 * of the \a metadata array of pointers so the client no longer needs
337 * to maintain it after the call. The objects themselves that are
338 * pointed to by the array are still not copied though and must be
339 * maintained until the call to FLAC__stream_encoder_finish().
342 /** \defgroup porting_1_1_4_to_1_2_0 Porting from FLAC 1.1.4 to 1.2.0
346 * This module describes porting from FLAC 1.1.4 to FLAC 1.2.0.
348 * There were only very minor changes to the interfaces from 1.1.4 to 1.2.0.
349 * In libFLAC, \c FLAC__format_sample_rate_is_subset() was added.
350 * In libFLAC++, \c FLAC::Decoder::Stream::get_decode_position() was added.
352 * Finally, value of the constant \c FLAC__FRAME_HEADER_RESERVED_LEN
353 * has changed to reflect the conversion of one of the reserved bits
354 * into active use. It used to be \c 2 and now is \c 1. However the
355 * FLAC frame header length has not changed, so to skip the proper
356 * number of bits, use \c FLAC__FRAME_HEADER_RESERVED_LEN +
357 * \c FLAC__FRAME_HEADER_BLOCKING_STRATEGY_LEN
360 /** \defgroup flac FLAC C API
362 * The FLAC C API is the interface to libFLAC, a set of structures
363 * describing the components of FLAC streams, and functions for
364 * encoding and decoding streams, as well as manipulating FLAC
367 * You should start with the format components as all other modules
368 * are dependent on it.