class EE::Audio::SoundFileReader¶

Overview¶

Abstract base class for sound file decoding. More…

#include <soundfilereader.hpp>

class SoundFileReader {
public:
    // structs

    struct Info;

    // construction

    virtual ~SoundFileReader();

    // methods

    virtual bool open(IOStream& stream, Info& info) = 0;
    virtual void seek(Uint64 sampleOffset) = 0;
    virtual Uint64 read(Int16* samples, Uint64 maxCount) = 0;
};

Detailed Documentation¶

Abstract base class for sound file decoding.

This class allows users to read audio file formats not natively supported by EEPP, and thus extend the set of supported readable audio formats.

A valid sound file reader must override the open, seek and write functions, as well as providing a static check function; the latter is used by EEPP to find a suitable writer for a given input file.

To register a new reader, use the SoundFileFactory::registerReader template function.

Usage example:

class MySoundFileReader : public SoundFileReader
{
public:

 static bool check(IOStream& stream)
 {
     // typically, read the first few header bytes and check fields that identify the format
     // return true if the reader can handle the format
 }

 virtual bool open(IOStream& stream, Info& info)
 {
     // read the sound file header and fill the sound attributes
     // (channel count, sample count and sample rate)
     // return true on success
 }

 virtual void seek(Uint64 sampleOffset)
 {
     // advance to the sampleOffset-th sample from the beginning of the sound
 }

 virtual Uint64 read(Int16* samples, Uint64 maxCount)
 {
     // read up to 'maxCount' samples into the 'samples' array,
     // convert them (for example from normalized float) if they are not stored
     // as 16-bits signed integers in the file
     // return the actual number of samples read
 }
};

SoundFileFactory::registerReader<MySoundFileReader>();

Methods¶

virtual bool open(IOStream& stream, Info& info) = 0

Open a sound file for reading.

The provided stream reference is valid as long as the SoundFileReader is alive, so it is safe to use/store it during the whole lifetime of the reader.

Parameters:

stream	Source stream to read from
info	Structure to fill with the properties of the loaded sound

Returns:

True if the file was successfully opened

virtual void seek(Uint64 sampleOffset) = 0

Change the current read position to the given sample offset.

The sample offset takes the channels into account. If you have a time offset instead, you can easily find the corresponding sample offset with the following formula: timeInSeconds * sampleRate * channelCount If the given offset exceeds to total number of samples, this function must jump to the end of the file.

Parameters:

sampleOffset

Index of the sample to jump to, relative to the beginning

virtual Uint64 read(Int16* samples, Uint64 maxCount) = 0

Read audio samples from the open file.

Parameters:

samples	Pointer to the sample array to fill
maxCount	Maximum number of samples to read

Returns:

Number of samples actually read (may be less than maxCount)