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Note: This API doc is automatically generated from the current development version that you can get via Subversion or as a daily snapshot from http://mpg123.org/snapshot. There may be differences (additions) compared to the latest stable release. See NEWS.libmpg123 and the overall NEWS file on libmpg123 versions and important changes between them.
Let me emphasize that the policy for libmpg123 is to always stay backwards compatible -- only additions are planned (and it's not yet planned to change the plans;-).
Typedefs | Enumerations | Functions

mpg123 library and handle setup

Typedefs

typedef struct mpg123_handle_struct mpg123_handle

Enumerations

enum  mpg123_parms {
  MPG123_VERBOSE = 0, MPG123_FLAGS,
  MPG123_ADD_FLAGS, MPG123_FORCE_RATE,
  MPG123_DOWN_SAMPLE, MPG123_RVA,
  MPG123_DOWNSPEED, MPG123_UPSPEED,
  MPG123_START_FRAME, MPG123_DECODE_FRAMES,
  MPG123_ICY_INTERVAL, MPG123_OUTSCALE,
  MPG123_TIMEOUT, MPG123_REMOVE_FLAGS,
  MPG123_RESYNC_LIMIT, MPG123_INDEX_SIZE,
  MPG123_PREFRAMES, MPG123_FEEDPOOL,
  MPG123_FEEDBUFFER
}
enum  mpg123_param_flags {
  MPG123_FORCE_MONO = 0x7, MPG123_MONO_LEFT = 0x1,
  MPG123_MONO_RIGHT = 0x2, MPG123_MONO_MIX = 0x4,
  MPG123_FORCE_STEREO = 0x8, MPG123_FORCE_8BIT = 0x10,
  MPG123_QUIET = 0x20, MPG123_GAPLESS = 0x40,
  MPG123_NO_RESYNC = 0x80, MPG123_SEEKBUFFER = 0x100,
  MPG123_FUZZY = 0x200, MPG123_FORCE_FLOAT = 0x400,
  MPG123_PLAIN_ID3TEXT = 0x800, MPG123_IGNORE_STREAMLENGTH = 0x1000,
  MPG123_SKIP_ID3V2 = 0x2000, MPG123_IGNORE_INFOFRAME = 0x4000,
  MPG123_AUTO_RESAMPLE = 0x8000
}
enum  mpg123_param_rva {
  MPG123_RVA_OFF = 0, MPG123_RVA_MIX = 1,
  MPG123_RVA_ALBUM = 2, MPG123_RVA_MAX = MPG123_RVA_ALBUM
}
enum  mpg123_feature_set {
  MPG123_FEATURE_ABI_UTF8OPEN = 0, MPG123_FEATURE_OUTPUT_8BIT,
  MPG123_FEATURE_OUTPUT_16BIT, MPG123_FEATURE_OUTPUT_32BIT,
  MPG123_FEATURE_INDEX, MPG123_FEATURE_PARSE_ID3V2,
  MPG123_FEATURE_DECODE_LAYER1, MPG123_FEATURE_DECODE_LAYER2,
  MPG123_FEATURE_DECODE_LAYER3, MPG123_FEATURE_DECODE_ACCURATE,
  MPG123_FEATURE_DECODE_DOWNSAMPLE, MPG123_FEATURE_DECODE_NTOM,
  MPG123_FEATURE_PARSE_ICY, MPG123_FEATURE_TIMEOUT_READ
}

Functions

int mpg123_init (void)
void mpg123_exit (void)
mpg123_handlempg123_new (const char *decoder, int *error)
void mpg123_delete (mpg123_handle *mh)
int mpg123_param (mpg123_handle *mh, enum mpg123_parms type, long value, double fvalue)
int mpg123_getparam (mpg123_handle *mh, enum mpg123_parms type, long *val, double *fval)
int mpg123_feature (const enum mpg123_feature_set key)

Detailed Description

Functions to initialise and shutdown the mpg123 library and handles. The parameters of handles have workable defaults, you only have to tune them when you want to tune something;-) Tip: Use a RVA setting...


Typedef Documentation

typedef struct mpg123_handle_struct mpg123_handle

Opaque structure for the libmpg123 decoder handle. Most functions take a pointer to a mpg123_handle as first argument and operate on its data in an object-oriented manner.

Definition at line 110 of file mpg123.h.


Enumeration Type Documentation

Enumeration of the parameters types that it is possible to set/get.

Enumerator:
MPG123_VERBOSE 

set verbosity value for enabling messages to stderr, >= 0 makes sense (integer)

MPG123_FLAGS 

set all flags, p.ex val = MPG123_GAPLESS|MPG123_MONO_MIX (integer)

MPG123_ADD_FLAGS 

add some flags (integer)

MPG123_FORCE_RATE 

when value > 0, force output rate to that value (integer)

MPG123_DOWN_SAMPLE 

0=native rate, 1=half rate, 2=quarter rate (integer)

MPG123_RVA 

one of the RVA choices above (integer)

MPG123_DOWNSPEED 

play a frame N times (integer)

MPG123_UPSPEED 

play every Nth frame (integer)

MPG123_START_FRAME 

start with this frame (skip frames before that, integer)

MPG123_DECODE_FRAMES 

decode only this number of frames (integer)

MPG123_ICY_INTERVAL 

stream contains ICY metadata with this interval (integer)

MPG123_OUTSCALE 

the scale for output samples (amplitude - integer or float according to mpg123 output format, normally integer)

MPG123_TIMEOUT 

timeout for reading from a stream (not supported on win32, integer)

MPG123_REMOVE_FLAGS 

remove some flags (inverse of MPG123_ADD_FLAGS, integer)

MPG123_RESYNC_LIMIT 

Try resync on frame parsing for that many bytes or until end of stream (<0 ... integer). This can enlarge the limit for skipping junk on beginning, too (but not reduce it).

MPG123_INDEX_SIZE 

Set the frame index size (if supported). Values <0 mean that the index is allowed to grow dynamically in these steps (in positive direction, of course) -- Use this when you really want a full index with every individual frame.

MPG123_PREFRAMES 

Decode/ignore that many frames in advance for layer 3. This is needed to fill bit reservoir after seeking, for example (but also at least one frame in advance is needed to have all "normal" data for layer 3). Give a positive integer value, please.

MPG123_FEEDPOOL 

For feeder mode, keep that many buffers in a pool to avoid frequent malloc/free. The pool is allocated on mpg123_open_feed(). If you change this parameter afterwards, you can trigger growth and shrinkage during decoding. The default value could change any time. If you care about this, then set it. (integer)

MPG123_FEEDBUFFER 

Minimal size of one internal feeder buffer, again, the default value is subject to change. (integer)

Definition at line 135 of file mpg123.h.

Flag bits for MPG123_FLAGS, use the usual binary or to combine.

Enumerator:
MPG123_FORCE_MONO 

0111 Force some mono mode: This is a test bitmask for seeing if any mono forcing is active.

MPG123_MONO_LEFT 

0001 Force playback of left channel only.

MPG123_MONO_RIGHT 

0010 Force playback of right channel only.

MPG123_MONO_MIX 

0100 Force playback of mixed mono.

MPG123_FORCE_STEREO 

1000 Force stereo output.

MPG123_FORCE_8BIT 

00010000 Force 8bit formats.

MPG123_QUIET 

00100000 Suppress any printouts (overrules verbose).

MPG123_GAPLESS 

01000000 Enable gapless decoding (default on if libmpg123 has support).

MPG123_NO_RESYNC 

10000000 Disable resync stream after error.

MPG123_SEEKBUFFER 

000100000000 Enable small buffer on non-seekable streams to allow some peek-ahead (for better MPEG sync).

MPG123_FUZZY 

001000000000 Enable fuzzy seeks (guessing byte offsets or using approximate seek points from Xing TOC)

MPG123_FORCE_FLOAT 

010000000000 Force floating point output (32 or 64 bits depends on mpg123 internal precision).

MPG123_PLAIN_ID3TEXT 

100000000000 Do not translate ID3 text data to UTF-8. ID3 strings will contain the raw text data, with the first byte containing the ID3 encoding code.

MPG123_IGNORE_STREAMLENGTH 

1000000000000 Ignore any stream length information contained in the stream, which can be contained in a 'TLEN' frame of an ID3v2 tag or a Xing tag

MPG123_SKIP_ID3V2 

10 0000 0000 0000 Do not parse ID3v2 tags, just skip them.

MPG123_IGNORE_INFOFRAME 

100 0000 0000 0000 Do not parse the LAME/Xing info frame, treat it as normal MPEG data.

MPG123_AUTO_RESAMPLE 

1000 0000 0000 0000 Allow automatic internal resampling of any kind (default on if supported). Especially when going lowlevel with replacing output buffer, you might want to unset this flag. Setting MPG123_DOWNSAMPLE or MPG123_FORCE_RATE will override this.

Definition at line 159 of file mpg123.h.

choices for MPG123_RVA

Enumerator:
MPG123_RVA_OFF 

RVA disabled (default).

MPG123_RVA_MIX 

Use mix/track/radio gain.

MPG123_RVA_ALBUM 

Use album/audiophile gain

MPG123_RVA_MAX 

The maximum RVA code, may increase in future.

Definition at line 181 of file mpg123.h.

Feature set available for query with mpg123_feature.

Enumerator:
MPG123_FEATURE_ABI_UTF8OPEN 

mpg123 expects path names to be given in UTF-8 encoding instead of plain native.

MPG123_FEATURE_OUTPUT_8BIT 

8bit output

MPG123_FEATURE_OUTPUT_16BIT 

16bit output

MPG123_FEATURE_OUTPUT_32BIT 

32bit output

MPG123_FEATURE_INDEX 

support for building a frame index for accurate seeking

MPG123_FEATURE_PARSE_ID3V2 

id3v2 parsing

MPG123_FEATURE_DECODE_LAYER1 

mpeg layer-1 decoder enabled

MPG123_FEATURE_DECODE_LAYER2 

mpeg layer-2 decoder enabled

MPG123_FEATURE_DECODE_LAYER3 

mpeg layer-3 decoder enabled

MPG123_FEATURE_DECODE_ACCURATE 

accurate decoder rounding

MPG123_FEATURE_DECODE_DOWNSAMPLE 

downsample (sample omit)

MPG123_FEATURE_DECODE_NTOM 

flexible rate decoding

MPG123_FEATURE_PARSE_ICY 

ICY support

MPG123_FEATURE_TIMEOUT_READ 

Reader with timeout (network).

Definition at line 200 of file mpg123.h.


Function Documentation

int mpg123_init ( void   ) 

Function to initialise the mpg123 library. This function is not thread-safe. Call it exactly once per process, before any other (possibly threaded) work with the library.

Returns:
MPG123_OK if successful, otherwise an error number.
void mpg123_exit ( void   ) 

Function to close down the mpg123 library. This function is not thread-safe. Call it exactly once per process, before any other (possibly threaded) work with the library.

mpg123_handle* mpg123_new ( const char *  decoder,
int *  error 
)

Create a handle with optional choice of decoder (named by a string, see mpg123_decoders() or mpg123_supported_decoders()). and optional retrieval of an error code to feed to mpg123_plain_strerror(). Optional means: Any of or both the parameters may be NULL.

Returns:
Non-NULL pointer when successful.
void mpg123_delete ( mpg123_handle mh  ) 

Delete handle, mh is either a valid mpg123 handle or NULL.

int mpg123_param ( mpg123_handle mh,
enum mpg123_parms  type,
long  value,
double  fvalue 
)

Set a specific parameter, for a specific mpg123_handle, using a parameter type key chosen from the mpg123_parms enumeration, to the specified value.

int mpg123_getparam ( mpg123_handle mh,
enum mpg123_parms  type,
long *  val,
double *  fval 
)

Get a specific parameter, for a specific mpg123_handle. See the mpg123_parms enumeration for a list of available parameters.

int mpg123_feature ( const enum mpg123_feature_set  key  ) 

Query libmpg123 feature, 1 for success, 0 for unimplemented functions.

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