Synkronisering av audio- och videosignaler

摘要

The present invention relates to adaptive time-shifting of audio frames (F_a) in encoded audio signal relative to video frames (F_v) in encoded video signal, which together form an audio/video message steam such that the corresponding decoded audio and video signals are aligned in time within the maximum degree of deviation. The invention accomplishes this alignment by determining a desired delay of the encoded audio signal for the decoded signals to meet deviation requirement The desired (D_d) delay is then converted into a frame delay number (n_D), which is calculated as one of the two neighbouring integers to a ratio between the desired delay (D_d) and an interval (T_a) at which the audio frames (F_a) are received. A number of audio frames (F_a) equal to the frame delay number (n_D) are alternately stored into respective read out from FIFO-buffers ( 309; 310 ) such that sufficiently delayed audio frames (F_a) are delivered to an audio decoding unit ( 313 ). After signal decoding ( 313; 315 ) synchronized audio and video information can thus be presented via a loudspeaker ( 314 ) and a video monitor ( 316 ) respectively.