How do you make the delayed audio of a video match the visual of the video?

Answer 1

The introduction of digital television has brought some problems as well as many benefits. One such problem is that audio and video signals are processed in packets of data rather than strictly in real time (In other words, all data is delayed for a short amount of time while it is being sent, received or processed). For example, broadcast video signals are compressed for transmission and then un-compressed when they reach a domestic receiver. The process can take up to about a second and so the video signal is later than the audio. Audio processing adds similar delays to the sound. Receivers normally take the delays into account and make sure that the audio and video signals are in time with each other by the time they reach the viewer.

Audio can be out of time with the video for a number of reasons. Taking digital audio into a Home Theater system might add some additional delay. Running video through a scaler before it reaches the display may delay video in a similar way. The best way to overcome the problem is to avoid the delay in the first place.

If that is not possible, a careful read of the instruction manuals for all equipment in the system may reveal a method to delay a signal by a fixed amount, so getting audio and video back in time once more. If that doesn't do the job, then additional equipment may be needed. Audio delays and video delays can be obtained and they can be programmed to add certain delays to a signal. The equipment is not cheap and they can be difficult to set up properly.

If possible, try to keep all digital signals as digital throughout the signal chain. This will often eliminate the problem.

In the case of this question, the audio is later than the video, so a video delay will be needed. Make sure that the inputs and outputs on the delay are correct for the installation (HDMI, composite, S-video or component for example). Be sure that you understand where the delay is being caused to make sure that the delay is going to work reliably. For example, if the delay is only noticed on DVD replay, make sure the video delay unit does not delay signals coming from a cable receiver as well. Take the time to understand the problem and the solution will become simple. remember that video or home theater consultants may well be able to offer a cost effective solution far faster than a home owner is able to.