Dvd audio decoder having efficient deadlock handling

Abstract

An audio decoder makes use of various component sharing techniques and operates to efficiently prevent deadlock without introducing decoding errors or adding significant complexity to the audio decoder. In one embodiment, the audio decoder comprises a bitstreamer, a synchronization controller, a decode controller, a memory module, a data path, and an output buffer. The bitstreamer retrieves compressed data and provides token-aligned data to the synchronization controller and decode controller. The synchronization controller initially controls the bitstreamer to locate and parse audio frame headers. After each frame header is parsed, the decode controller controls the bitstreamer to parse the variable length code compressed transform coefficients. The coefficients are passed to the memory module and data path which operate under the control of the decode controller to inverse transform the coefficients and produce digital output audio data. The output buffer buffers the digital output audio data and asserts a underflow signal whenever the amount of buffered data falls below a predetermined threshold. The synchronization controller monitors this underflow signal and uses it as an indication of evidence of a decoding process failure which could be due to various causes including bitstream corruption. The synchronization controller then seizes control of the bitstreamer, locates the next audio frame, re-initiates the decode controller, and returns control of the bitstreamer to the decode controller. The synchronization controller may also perform error handling functions including muting of the output audio signal. This approach to preventing deadlock advantageously avoids the need for large delay timers and the risk of early bitstream seizure. Further, this approach provides the ability to detect and handle decoding errors from nearly any source in a simple and uniform way.