原创 How to sync video (TV) with audio (radio)

2016-1-21 18:23 1172 22 22 分类: 消费电子

In certain respects, things were much simpler in the old days. Take synchronizing images and sound, for example. In the case of traditional movie films, the analog soundtrack was included on the film itself, thereby ensuring that the two were fully synchronized. Similarly, in the case of video like VHS, audio tracks were recorded along the top edge of the tape, thereby ensuring synchronization with the images.

 

Things are more complicated these days, with audio and video being processed by largely separate subsystems, which goes some way to explain why -- when you are watching a modern television program -- people's lips often appear to move completely independently of the words they are saying (much like watching a badly dubbed Godzilla movie from Japan circa 20 years ago).

 


(Source: pixabay.com)
 

It seems a tad ironic that we have such amazing home entertainment systems these days -- with high-definition video (which is already moving to 4K x 2K) and surround-sound audio -- yet we appear to be incapable of getting the sound to be synchronized with the images. As a somewhat related problem, if I have the same program playing on multiple televisions in my house -- say the family room and the kitchen -- there's a noticeable delay between the two systems resulting in a very annoying echo-type effect. It makes you want to cry.

 

I seem to recall that there's a lot of work going on at the moment to sort this problem out by associating time-stamps with both the audio and video and then delaying one or the other to ensure that they are fully synchronized but (a) I forget the details and (b) that's not what I wanted to talk to you about.

 

The thing is that I was chatting to a friend-of-a-friend the other day, and he posed an interesting problem. It seems that he prefers to watch American football on his television while listening to the commentary on his radio.

 

I was a bit puzzled as to why he wanted to do this, but he explained that both the game (on the TV) and the commentary (on the radio) are transmitted in real time -- however the commentary continues when the TV breaks for adverts, and he prefers to listen to the ongoing discussions about the plays and suchlike rather than watching adverts for things like hemorrhoid creams (and who amongst our number would argue with this philosophy?).

 

The problem comes with regard to our definition of "real time" because -- even though the video and audio are going out "live" -- they are traveling and being processed via different systems, which means that there can ensue quite a large miss-sync amounting to multiple seconds in some cases.

 

So, this friend-of-a-friend was asking as to the best way to address this problem. My knee-jerk suggestion was to forget the football and instead watch Dr. Who, but it seems this is not a satisfactory solution (you just can't please some people).

 

So, is this guy "one in a million," or is this a common problem to which there's already an existing solution? Alternatively, does any possible solution spring into your mind? If so, please share it with the rest of us in the comments below.

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