st->codec->sample_rate = rate;
if (data_size != AU_UNKNOWN_SIZE)
st->duration = (((int64_t)data_size)<<3) / (st->codec->channels * bps);
st->codec->sample_rate = rate;
if (data_size != AU_UNKNOWN_SIZE)
st->duration = (((int64_t)data_size)<<3) / (st->codec->channels * bps);