Madrigal engineers have developed a proprietary buffer management scheme which reduces reproduced jitter to less than 20 picoseconds while maintaining the synchronization of sound and picture in movies. It employs a buffer large enough to absorb the jitter found in transports of reasonable quality, yet small enough to have impreceptible delay. The rate at which data is released from the FIFO buffer is controlled by software to track the long-term data rate of the in- coming signal, allowing the buffer to absorb all the short-term variations which cause sonic degradation. This approach yields a “smart” FIFO buffering scheme which rejects virtually all incoming jitter without requiring an enormous buffer and the consequent audible delay. It also avoids the sonic penalties associated with the usual strategies used when a buffer overflows or empties.
哈哈～果然是搞這招～
沒啥奇怪，工程師應該都想的到，只是要動用個VCXO與counter而已。
這招的最大限制在於，要多久調整一次clock頻率才聽不出來？
這又有個變因，FIFO要多大才能吃下誤差不致於爆音？
真正的關鍵是，latency會多長？
太長就不能看影片，對嘴對不上
喔，五年前我就寫完這個algorithm分析丟給幾個同事看過了。
沒有留言:
張貼留言