mpg123 library and handle setup

Collaboration diagram for mpg123 library and handle setup:

Modules
	mpg123 error handling

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 , MPG123_FREEFORMAT_SIZE }
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 , MPG123_PICTURE = 0x10000 , MPG123_NO_PEEK_END = 0x20000 , MPG123_FORCE_SEEKABLE = 0x40000 ,   MPG123_STORE_RAW_ID3 = 0x80000 , MPG123_FORCE_ENDIAN = 0x100000 , MPG123_BIG_ENDIAN = 0x200000 , MPG123_NO_READAHEAD = 0x400000 ,   MPG123_FLOAT_FALLBACK = 0x800000 , MPG123_NO_FRANKENSTEIN = 0x1000000 }
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 , MPG123_FEATURE_EQUALIZER , MPG123_FEATURE_MOREINFO ,   MPG123_FEATURE_OUTPUT_FLOAT32 , MPG123_FEATURE_OUTPUT_FLOAT64 }

Functions
MPG123_EXPORT int	mpg123_init (void)
MPG123_EXPORT void	mpg123_exit (void)
MPG123_EXPORT mpg123_handle *	mpg123_new (const char *decoder, int *error)
MPG123_EXPORT void	mpg123_delete (mpg123_handle *mh)
MPG123_EXPORT void	mpg123_free (void *ptr)
MPG123_EXPORT int	mpg123_param (mpg123_handle *mh, enum mpg123_parms type, long value, double fvalue)
MPG123_EXPORT int	mpg123_getparam (mpg123_handle *mh, enum mpg123_parms type, long *value, double *fvalue)
MPG123_EXPORT int	mpg123_feature (const enum mpg123_feature_set key)
MPG123_EXPORT int	mpg123_feature2 (int 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

mpg123_handle

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 140 of file mpg123.h.

Enumeration Type Documentation

mpg123_feature_set

enum mpg123_feature_set

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).
MPG123_FEATURE_EQUALIZER	tunable equalizer
MPG123_FEATURE_MOREINFO	more info extraction (for frame analyzer)
MPG123_FEATURE_OUTPUT_FLOAT32	32 bit float output
MPG123_FEATURE_OUTPUT_FLOAT64	64 bit float output (usually never)

Definition at line 303 of file mpg123.h.

{
     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         
    ,MPG123_FEATURE_EQUALIZER            
    ,MPG123_FEATURE_MOREINFO             
    ,MPG123_FEATURE_OUTPUT_FLOAT32      
    ,MPG123_FEATURE_OUTPUT_FLOAT64      
};

mpg123_param_flags

enum mpg123_param_flags

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.
MPG123_PICTURE	17th bit: Enable storage of pictures from tags (ID3v2 APIC).
MPG123_NO_PEEK_END	18th bit: Do not seek to the end of the stream in order to probe the stream length and search for the id3v1 field. This also means the file size is unknown unless set using mpg123_set_filesize() and the stream is assumed as non-seekable unless overridden.
MPG123_FORCE_SEEKABLE	19th bit: Force the stream to be seekable.
MPG123_STORE_RAW_ID3	store raw ID3 data (even if skipping)
MPG123_FORCE_ENDIAN	Enforce endianess of output samples. This is not reflected in the format codes. If this flag is set along with MPG123_BIG_ENDIAN, MPG123_ENC_SIGNED16 means s16be, without MPG123_BIG_ENDIAN, it means s16le. Normal operation without MPG123_FORCE_ENDIAN produces output in native byte order.
MPG123_BIG_ENDIAN	Choose big endian instead of little.
MPG123_NO_READAHEAD	Disable read-ahead in parser. If you know you provide full frames to the feeder API, this enables decoder output from the first one on, instead of having to wait for the next frame to confirm that the stream is healthy. It also disables free format support unless you provide a frame size using MPG123_FREEFORMAT_SIZE.
MPG123_FLOAT_FALLBACK	Consider floating point output encoding only after trying other (possibly downsampled) rates and encodings first. This is to support efficient playback where floating point output is only configured for an external resampler, bypassing that resampler when the desired rate can be produced directly. This is enabled by default to be closer to older versions of libmpg123 which did not enable float automatically at all. If disabled, float is considered after the 16 bit default and higher-bit integer encodings for any rate.
MPG123_NO_FRANKENSTEIN	Disable support for Frankenstein streams (different MPEG streams stiched together). Do not accept serious change of MPEG header inside a single stream. With this flag, the audio output format cannot change during decoding unless you open a new stream. This also stops decoding after an announced end of stream (Info header contained a number of frames and this number has been reached). This makes your MP3 files behave more like ordinary media files with defined structure, rather than stream dumps with some sugar.

Definition at line 211 of file mpg123.h.

{
     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 
    ,MPG123_PICTURE = 0x10000 
    ,MPG123_NO_PEEK_END    = 0x20000 
    ,MPG123_FORCE_SEEKABLE = 0x40000 
    ,MPG123_STORE_RAW_ID3  = 0x80000 
    ,MPG123_FORCE_ENDIAN   = 0x100000 
    ,MPG123_BIG_ENDIAN     = 0x200000 
    ,MPG123_NO_READAHEAD   = 0x400000 
    ,MPG123_FLOAT_FALLBACK = 0x800000 
    ,MPG123_NO_FRANKENSTEIN = 0x1000000 
};

mpg123_param_rva

enum mpg123_param_rva

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 272 of file mpg123.h.

{
     MPG123_RVA_OFF   = 0 
    ,MPG123_RVA_MIX   = 1 
    ,MPG123_RVA_ALBUM = 2 
    ,MPG123_RVA_MAX   = MPG123_RVA_ALBUM 
};

mpg123_parms

enum mpg123_parms

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). Make sure to set this before opening a stream.
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)
MPG123_FREEFORMAT_SIZE	Tell the parser a free-format frame size to avoid read-ahead to get it. A value of -1 (default) means that the parser will determine it. The parameter value is applied during decoder setup for a freshly opened stream only.

Definition at line 181 of file mpg123.h.

{
    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 
    ,MPG123_FREEFORMAT_SIZE 
};

Function Documentation

mpg123_delete()

MPG123_EXPORT void mpg123_delete

(

mpg123_handle *

mh

)

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

Parameters

mh

handle

Definition at line 1712 of file libmpg123.c.

{
    if(mh != NULL)
    {
        mpg123_close(mh);
        frame_exit(mh); /* free buffers in frame */
        free(mh); /* free struct; cast? */
    }
}

mpg123_exit()

MPG123_EXPORT void mpg123_exit

(

void

)

Superfluous Function to close down the mpg123 library. This was created with the thought that there sometime will be cleanup code to be run after library use. This never materialized. You can forget about this function and it is only here for old programs that do call it.

Definition at line 50 of file libmpg123.c.

{
    /* nothing yet, but something later perhaps */
    /* Nope. This is dead space. */
}

mpg123_feature()

MPG123_EXPORT int mpg123_feature

(

const enum mpg123_feature_set

key

)

Query libmpg123 features.

Parameters

key	feature selection

Returns

1 for success, 0 for unimplemented functions

Definition at line 8 of file feature.c.

{
    switch(key)
    {
        case MPG123_FEATURE_ABI_UTF8OPEN:
#ifdef WANT_WIN32_UNICODE
        return 1;
#else
        return 0;
#endif /* WANT_WIN32_UNICODE */
 
        case MPG123_FEATURE_OUTPUT_8BIT:
#ifdef NO_8BIT
        return 0;
#else
        return 1;
#endif /* mpg123_output_8bit */
 
        case MPG123_FEATURE_OUTPUT_16BIT:
#ifdef NO_16BIT
        return 0;
#else
        return 1;
#endif /* mpg123_output_16bit */
 
        case MPG123_FEATURE_OUTPUT_32BIT:
#ifdef NO_32BIT
        return 0;
#else
        return 1;
#endif /* mpg123_output_32bit */
 
        case MPG123_FEATURE_OUTPUT_FLOAT32:
#if defined(NO_REAL) || defined(REAL_IS_DOUBLE)
        return 0;
#else
        return 1;
#endif
 
        case MPG123_FEATURE_OUTPUT_FLOAT64:
#if defined(NO_REAL) || !defined(REAL_IS_DOUBLE)
        return 0;
#else
        return 1;
#endif
 
        case MPG123_FEATURE_PARSE_ID3V2:
#ifdef NO_ID3V2
        return 0;
#else
        return 1;
#endif /* NO_ID3V2 */
 
        case MPG123_FEATURE_DECODE_LAYER1:
#ifdef NO_LAYER1
        return 0;
#else
        return 1;
#endif /* NO_LAYER1 */
 
        case MPG123_FEATURE_DECODE_LAYER2:
#ifdef NO_LAYER2
        return 0;
#else
        return 1;
#endif /* NO_LAYER2 */
 
        case MPG123_FEATURE_DECODE_LAYER3:
#ifdef NO_LAYER3
        return 0;
#else
        return 1;
#endif /* NO_LAYER3 */
 
        case MPG123_FEATURE_DECODE_ACCURATE:
#ifdef ACCURATE_ROUNDING
        return 1;
#else
        return 0;
#endif /* ACCURATE_ROUNDING */
 
        case MPG123_FEATURE_DECODE_DOWNSAMPLE:
#ifdef NO_DOWNSAMPLE
        return 0;
#else
        return 1;
#endif /* NO_DOWNSAMPLE */
 
        case MPG123_FEATURE_DECODE_NTOM:
#ifdef NO_NTOM
        return 0;
#else
        return 1;
#endif /* NO_NTOM */
 
        case MPG123_FEATURE_PARSE_ICY:
#ifdef NO_ICY
        return 0;
#else
        return 1;
#endif /* NO_ICY */
 
        case MPG123_FEATURE_INDEX:
#ifdef FRAME_INDEX
        return 1;
#else
        return 0;
#endif /* FRAME_INDEX */
        case MPG123_FEATURE_TIMEOUT_READ:
#ifdef TIMEOUT_READ
        return 1;
#else
        return 0;
#endif
        case MPG123_FEATURE_EQUALIZER:
#ifndef NO_EQUALIZER
        return 1;
#else
        return 0;
#endif
        case MPG123_FEATURE_MOREINFO:
#ifndef NO_MOREINFO
        return 1;
#else
        return 0;
#endif
 
        default: return 0;
    }
}

Referenced by mpg123_feature2().

mpg123_feature2()

MPG123_EXPORT int mpg123_feature2

(

int

key

)

Query libmpg123 features with better ABI compatibility

This is the same as mpg123_feature(), but this time not using the enum as argument. Compilers don't have to agree on the size of enums and hence they are not safe in public API.

Parameters

key	feature selection

Returns

1 for success, 0 for unimplemented functions

Definition at line 3 of file feature.c.

{
    return mpg123_feature(key);
}

mpg123_free()

MPG123_EXPORT void mpg123_free

(

void *

ptr

)

Free plain memory allocated within libmpg123. This is for library users that are not sure to use the same underlying memory allocator as libmpg123. It is just a wrapper over free() in the underlying C library.

Definition at line 1722 of file libmpg123.c.

{
    free(ptr);
}

mpg123_getparam()

MPG123_EXPORT int mpg123_getparam	(	mpg123_handle *	mh,
		enum mpg123_parms	type,
		long *	value,
		double *	fvalue
	)

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

Parameters

mh	handle
type	parameter choice
value	integer value return address
fvalue	floating point value return address

Returns

MPG123_OK on success

Definition at line 268 of file libmpg123.c.

{
    int r;
 
    if(mh == NULL) return MPG123_BAD_HANDLE;
    r = mpg123_getpar(&mh->p, key, val, fval);
    if(r != MPG123_OK){ mh->err = r; r = MPG123_ERR; }
    return r;
}

mpg123_init()

MPG123_EXPORT int mpg123_init

(

void

)

Function to initialise the mpg123 library. This should be called once in a non-parallel context. It is not explicitly thread-safe, but repeated/concurrent calls still should be safe as static tables are filled with the same values anyway.

Returns

MPG123_OK if successful, otherwise an error number.

Definition at line 23 of file libmpg123.c.

{
    if((sizeof(short) != 2) || (sizeof(long) < 4)) return MPG123_BAD_TYPES;
 
    if(initialized) return MPG123_OK; /* no need to initialize twice */
 
#ifndef NO_LAYER12
    init_layer12(); /* inits also shared tables with layer1 */
#endif
#ifndef NO_LAYER3
    init_layer3();
#endif
    prepare_decode_tables();
    check_decoders();
    initialized = 1;
#if (defined REAL_IS_FLOAT) && (defined IEEE_FLOAT)
    /* This is rather pointless but it eases my mind to check that we did
       not enable the special rounding on a VAX or something. */
    if(12346 != REAL_TO_SHORT_ACCURATE(12345.67f))
    {
        error("Bad IEEE 754 rounding. Re-build libmpg123 properly.");
        return MPG123_ERR;
    }
#endif
    return MPG123_OK;
}

mpg123_new()

MPG123_EXPORT 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.

Parameters

decoder	optional choice of decoder variant (NULL for default)
error	optional address to store error codes

Returns

Non-NULL pointer to fresh handle when successful.

Definition at line 57 of file libmpg123.c.

{
    return mpg123_parnew(NULL, decoder, error);
}

mpg123_param()

MPG123_EXPORT 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.

Parameters

mh	handle
type	parameter choice
value	integer value
fvalue	floating point value

Returns

MPG123_OK on success

Definition at line 127 of file libmpg123.c.

{
    int r;
 
    if(mh == NULL) return MPG123_BAD_HANDLE;
    r = mpg123_par(&mh->p, key, val, fval);
    if(r != MPG123_OK){ mh->err = r; r = MPG123_ERR; }
    else
    { /* Special treatment for some settings. */
#ifdef FRAME_INDEX
        if(key == MPG123_INDEX_SIZE)
        { /* Apply frame index size and grow property on the fly. */
            r = frame_index_setup(mh);
            if(r != MPG123_OK) mh->err = MPG123_INDEX_FAIL;
        }
#endif
#ifndef NO_FEEDER
        /* Feeder pool size is applied right away, reader will react to that. */
        if(key == MPG123_FEEDPOOL || key == MPG123_FEEDBUFFER)
        bc_poolsize(&mh->rdat.buffer, mh->p.feedpool, mh->p.feedbuffer);
#endif
    }
    return r;
}