Packging LEFT and RIGHT channel data - c++

Question

I am decoding FLAC audio into memory, and passing the decoded audio data to the OpenAL: void alBufferData (ALuint bufferName, ALenum format, const ALvoid *data, ALsizei size, ALsizei frequency);
The data from the decoded audio goes into mine std::vector<FLAC__int32> data_;. Into which I am attempting to package the LEFT and RIGHT channels (AL_FORMAT_STEREO16). However, I don't understand how I am to store/align these channels within my data_ vector.
So I have the libFLAC virtual callback member function:
FLAC__StreamDecoderWriteStatus
Source::write_callback (
FLAC__Frame const* _frame, FLAC__int32 const *const _buffer[])
{
for(size_t i(0); i < _frame->header.blocksize; i++) {
data_[index_] = _buffer[0][i]; // channel audio on the left
++index_;
data_[index_] = _buffer[1][i]; // what about the right channel?
} // jump
return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
} // main
At the moment, during audio playback, I am hearing only the LEFT channel. There is static sound after the sound has finished playing which I am assuming is the missing RIGHT channel data. How do i get the RIGHT channel to work also?
Also, this is the metadata callback signature as per libFLAC:
void
Source::metadata_callback (const ::FLAC__StreamMetadata *metadata)
{
total_samples_ = metadata->data.stream_info.total_samples;
rate_ = metadata->data.stream_info.sample_rate;
channels_ = metadata->data.stream_info.channels;
bps_ = metadata->data.stream_info.bits_per_sample;
switch (bps_) {
case 16 :
if (channels_ > 1) {
format_ = AL_FORMAT_STEREO16; } else {
format_ = AL_FORMAT_MONO16; }
break;
case 8 :
if (channels_ > 1) {
format_ = AL_FORMAT_STEREO8; } else {
format_ = AL_FORMAT_MONO8; }
break;
default:
break;
}
size_ = (ALuint)(rate_ * channels_ * (bps_ / 8));
data_.resize(total_samples_); index_ = 0;
} // main

Answer 1

A solution which works, was to assagned the below struct as the vector data type like so:
struct Data
{
FLAC__int16 channelLeft_;
FLAC__int16 channelRight_;
};
std::vector<Source::Data> data_;
than assign the size_ like so:
size_ = total_samples_ * sizeof(Source::Data);
finaly the data loop should now be:
for(size_t i(0); i < _frame->header.blocksize; i++) {
data_[index_].channelLeft_ = _buffer[0][i];
data_[index_].channelRight_ = _buffer[1][i];
++index_;
} // jump