In a repeated quantization scenario, apart from the nominal quantization error, an additional tandem error is introduced. The amount of the excess tandem error depends on the characteristics of the quantizers used. In this work, the effect of tandem error and its dependence on the underlying quantizer characteristics are analyzed. A prime example where tandem error leads to increased noise is in audio transcoding. The behavior of tandem-noise for typical audio coding methods such as MPEG 1 Layer 2 is investigated. A method of reducing the tandem errors is proposed. This method involves guiding the quantization process of the first quantizer, assuming prior knowledge of the second quantizer. Results show that the method is able to reduce the amount of tandem error in the repeated quantization scenario.
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