Classes | Typedefs | Functions

fishsound.h File Reference

The libfishsound C API. More...

#include <fishsound/constants.h>
#include <fishsound/decode.h>
#include <fishsound/encode.h>
#include <fishsound/comments.h>
#include <fishsound/deprecated.h>
Include dependency graph for fishsound.h:
This graph shows which files directly or indirectly include this file:

Classes

struct  FishSoundInfo
 Info about a particular encoder/decoder instance. More...
struct  FishSoundFormat
 Info about a particular sound format. More...

Typedefs

typedef void * FishSound
 An opaque handle to a FishSound.

Functions

int fish_sound_identify (unsigned char *buf, long bytes)
 Identify a codec based on the first few bytes of data.
FishSoundfish_sound_new (int mode, FishSoundInfo *fsinfo)
 Instantiate a new FishSound* handle.
long fish_sound_flush (FishSound *fsound)
 Flush any internally buffered data, forcing encode.
int fish_sound_reset (FishSound *fsound)
 Reset the codec state of a FishSound object.
int fish_sound_delete (FishSound *fsound)
 Delete a FishSound object.
int fish_sound_command (FishSound *fsound, int command, void *data, int datasize)
 Command interface.
int fish_sound_get_interleave (FishSound *fsound)
 Query whether a FishSound object is using interleaved PCM.
long fish_sound_get_frameno (FishSound *fsound)
 Query the current frame number of a FishSound object.
int fish_sound_set_frameno (FishSound *fsound, long frameno)
 Set the current frame number of a FishSound object.
int fish_sound_prepare_truncation (FishSound *fsound, long next_granulepos, int next_eos)
 Prepare truncation details for the next block of data.

Detailed Description

The libfishsound C API.

General usage

All access is managed via a FishSound* handle. This is instantiated using fish_sound_new() and should be deleted with fish_sound_delete() when no longer required. If there is a discontinuity in the input data (eg. after seeking in an input file), call fish_sound_reset() to reset the internal codec state.

Decoding

libfishsound provides callback based decoding: you feed it encoded audio data, and it will call your callback with decoded PCM. A more detailed explanation and a full example of decoding Ogg FLAC, Speex and Ogg Vorbis files is provided in the Decoding audio data section.

Encoding

libfishsound provides callback based encoding: you feed it PCM audio, and it will call your callback with encoded audio data. A more detailed explanation and a full example of encoding Ogg FLAC, Speex and Ogg Vorbis files is provided in the Encoding audio data section.


Typedef Documentation

typedef void* FishSound

An opaque handle to a FishSound.

This is returned by fishsound_new() and is passed to all other fish_sound_*() functions.


Function Documentation

int fish_sound_command ( FishSound fsound,
int  command,
void *  data,
int  datasize 
)

Command interface.

Parameters:
fsound A FishSound* handle
command The command action
data Command data
datasize Size of the data in bytes
Returns:
0 on success, -1 on failure
int fish_sound_delete ( FishSound fsound  ) 

Delete a FishSound object.

Parameters:
fsound A FishSound* handle
Returns:
0 on success, -1 on failure
long fish_sound_flush ( FishSound fsound  ) 

Flush any internally buffered data, forcing encode.

Parameters:
fsound A FishSound* handle
Returns:
0 on success, -1 on failure
long fish_sound_get_frameno ( FishSound fsound  ) 

Query the current frame number of a FishSound object.

For decoding, this is the greatest frame index that has been decoded and made available to a FishSoundDecoded callback. This function is safe to call from within a FishSoundDecoded callback, and corresponds to the frame number of the last frame in the current decoded block.

For encoding, this is the greatest frame index that has been encoded. This function is safe to call from within a FishSoundEncoded callback, and corresponds to the frame number of the last frame encoded in the current block.

Parameters:
fsound A FishSound* handle
Returns:
The current frame number
Return values:
-1 Invalid fsound
int fish_sound_get_interleave ( FishSound fsound  ) 

Query whether a FishSound object is using interleaved PCM.

Parameters:
fsound A FishSound* handle
Return values:
0 fsound uses non-interleaved PCM
1 fsound uses interleaved PCM
-1 Invalid fsound, or out of memory.
int fish_sound_identify ( unsigned char *  buf,
long  bytes 
)

Identify a codec based on the first few bytes of data.

Parameters:
buf A pointer to the first few bytes of the data
bytes The count of bytes available at buf
Return values:
FISH_SOUND_xxxxxx FISH_SOUND_VORBIS, FISH_SOUND_SPEEX or FISH_SOUND_FLAC if buf was identified as the initial bytes of a supported codec
FISH_SOUND_UNKNOWN if the codec could not be identified
FISH_SOUND_ERR_SHORT_IDENTIFY if bytes is less than 8
Note:
If bytes is exactly 8, then only a weak check is performed, which is fast but may return a false positive.
If bytes is greater than 8, then a stronger check is performed in which an attempt is made to decode buf as the initial header of each supported codec. This is unlikely to return a false positive but is only useful if buf is the entire payload of a packet derived from a lower layer such as Ogg framing or UDP datagrams.
FishSound* fish_sound_new ( int  mode,
FishSoundInfo fsinfo 
)

Instantiate a new FishSound* handle.

Parameters:
mode FISH_SOUND_DECODE or FISH_SOUND_ENCODE
fsinfo Encoder configuration, may be NULL for FISH_SOUND_DECODE
Returns:
A new FishSound* handle, or NULL on error
int fish_sound_prepare_truncation ( FishSound fsound,
long  next_granulepos,
int  next_eos 
)

Prepare truncation details for the next block of data.

The semantics of these parameters derives directly from Ogg encapsulation of Vorbis, described here.

When decoding from Ogg, you should call this function with the granulepos and eos of the ogg_packet structure. This call should be made before passing the packet's data to fish_sound_decode(). Failure to do so may result in minor decode errors on the first and/or last packet of the stream.

When encoding into Ogg, you should call this function with the granulepos and eos that will be used for the ogg_packet structure. This call should be made before passing the block of audio data to fish_sound_encode_*(). Failure to do so may result in minor encoding errors on the first and/or last packet of the stream.

Parameters:
fsound A FishSound* handle
next_granulepos The "granulepos" for the next block to decode. If unknown, set next_granulepos to -1. Otherwise, next_granulepos specifies the frameno of the final frame in the block. This is authoritative, hence can be used to indicate various forms of truncation at the beginning or end of a stream. Mid-stream, a later-than-expected "granulepos" indicates that some data was missing.
next_eos A boolean indicating whether the next data block will be the last in the stream.
Return values:
0 Success
-1 Invalid fsound
int fish_sound_reset ( FishSound fsound  ) 

Reset the codec state of a FishSound object.

When decoding from a seekable file, fish_sound_reset() should be called after any seek operations. See also fish_sound_set_frameno().

Parameters:
fsound A FishSound* handle
Returns:
0 on success, -1 on failure
int fish_sound_set_frameno ( FishSound fsound,
long  frameno 
)

Set the current frame number of a FishSound object.

When decoding from a seekable file, fish_sound_set_frameno() should be called after any seek operations, otherwise the value returned by fish_sound_get_frameno() will simply continue to increment. See also fish_sound_reset().

Parameters:
fsound A FishSound* handle
frameno The current frame number.
Return values:
0 Success
-1 Invalid fsound