gzdoom/src/sound/audio_mpg123_decoder.cpp

#include "i_soundinternal.h"

#ifdef HAVE_MPG123
static bool inited = false;


off_t MPG123Decoder::mem_lseek(void *handle, off_t offset, int whence)
{
    MPG123Decoder *self = reinterpret_cast<MPG123Decoder*>(handle);

    switch(whence)
    {
        case SEEK_SET:
            if(offset < 0 || offset > (off_t)self->MemLength)
                return -1;
            self->MemPos = offset;
            break;

        case SEEK_CUR:
            if((offset > 0 && (off_t)(self->MemLength-self->MemPos) < offset) ||
               (offset < 0 && (off_t)self->MemPos < -offset))
                return -1;
            self->MemPos += offset;
            break;

        case SEEK_END:
            if(offset > 0 || -offset > (off_t)self->MemLength)
                return -1;
            self->MemPos = self->MemLength + offset;
            break;

        default:
            return -1;
    }

    return self->MemPos;
}

ssize_t MPG123Decoder::mem_read(void *handle, void *buffer, size_t bytes)
{
    MPG123Decoder *self = reinterpret_cast<MPG123Decoder*>(handle);

    if(bytes > self->MemLength-self->MemPos)
        bytes = self->MemLength-self->MemPos;

    memcpy(buffer, self->MemData+self->MemPos, bytes);
    self->MemPos += bytes;

    return bytes;
}


MPG123Decoder::~MPG123Decoder()
{
    if(MPG123)
    {
        mpg123_close(MPG123);
        mpg123_delete(MPG123);
        MPG123 = 0;
    }
}

bool MPG123Decoder::open(const char *data, size_t length)
{
    if(!inited)
    {
        if(mpg123_init() != MPG123_OK)
            return false;
        inited = true;
    }

    MemData = data;
    MemPos = 0;
    MemLength = length;

    MPG123 = mpg123_new(NULL, NULL);
    if(mpg123_replace_reader_handle(MPG123, mem_read, mem_lseek, NULL) == MPG123_OK &&
       mpg123_open_handle(MPG123, this) == MPG123_OK)
    {
        int enc, channels;
        long srate;

        if(mpg123_getformat(MPG123, &srate, &channels, &enc) == MPG123_OK)
        {
            if((channels == 1 || channels == 2) && srate > 0 &&
               mpg123_format_none(MPG123) == MPG123_OK &&
               mpg123_format(MPG123, srate, channels, MPG123_ENC_SIGNED_16) == MPG123_OK)
            {
                // All OK
                Done = false;
                return true;
            }
        }
        mpg123_close(MPG123);
    }
    mpg123_delete(MPG123);
    MPG123 = 0;

    return false;
}

void MPG123Decoder::getInfo(int *samplerate, ChannelConfig *chans, SampleType *type)
{
    int enc = 0, channels = 0;
    long srate = 0;

    mpg123_getformat(MPG123, &srate, &channels, &enc);

    *samplerate = srate;

    if(channels == 2)
        *chans = ChannelConfig_Stereo;
    else
        *chans = ChannelConfig_Mono;

    *type = SampleType_Int16;
}

size_t MPG123Decoder::read(char *buffer, size_t bytes)
{
    size_t amt = 0;
    while(!Done && bytes > 0)
    {
        size_t got = 0;
        int ret = mpg123_read(MPG123, (unsigned char*)buffer, bytes, &got);

        bytes -= got;
        buffer += got;
        amt += got;

        if(ret == MPG123_NEW_FORMAT || ret == MPG123_DONE || got == 0)
        {
            Done = true;
            break;
        }
    }
    return amt;
}

bool MPG123Decoder::open(const char *fname, size_t offset, size_t length)
{
    return false;
}

bool MPG123Decoder::seek(size_t ms_offset)
{
    int enc, channels;
    long srate;

    if(mpg123_getformat(MPG123, &srate, &channels, &enc) == MPG123_OK)
    {
        size_t smp_offset = (size_t)((double)ms_offset / 1000. * srate);
        if(mpg123_seek(MPG123, smp_offset, SEEK_SET) >= 0)
        {
            Done = false;
            return true;
        }
    }
    return false;
}

size_t MPG123Decoder::getSampleOffset()
{
    return mpg123_tell(MPG123);
}

#endif