Patent ID: 7548585
Filing Date: 2009-06-16
Classification: G06F,H04L

Abstract:
1. A method for adjusting a playback frequency for playing back an audio stream on a playback device, the method comprising: capturing the audio stream at an audio source device; filling a source buffer provided by the audio source device with at least a portion of the audio stream; packetizing the audio source into a corresponding audio sample; sending the audio sample over a network to a playback buffer provided by the playback device; receiving the audio sample at the playback buffer; playing back at least a portion of the audio sample from the playback buffer at the playback frequency; and adjusting a buffer fill level associated with the playback buffer when the buffer level is not within a designated target range, wherein adjusting the buffer level of the playback buffer includes: adapting the playback frequency by combining the determined offset frequency with a frequency at which the audio sample is arriving at the playback buffer, so as to increase or decrease the frequency at which the audio sample is played from the playback buffer and to adjust the current fill level into the designated target range, the playback frequency being increased or decreased in a graduated manner to prevent perceptible degradation in the audio sample during playback, wherein the audio stream does not encode frequency information, and wherein adapting the playback frequency includes: establishing the designated target range to be between 40-60% of capacity of the playback buffer; determining whether more audio data remains in the playback buffer; continuing to release audio data from the playback buffer as long as audio remains in the playback buffer; and maintaining at least 200 ms of audio data in the playback buffer at all times.