I just watched a digitally remastered episode of Law and Order in HD. The picture quality was basically the same as if it was done yeasterday. The haircuts not so much. It was an early 90s / late 80s episode. One thing that jumped out at me right away was that the sound, especially the classic bass / sax theme song was “wobbly”, “vibtrato-y” for a lack of a better word. Why does the digitally remastering process screw up the sound aspect of these old episodes, but the video seems ok?
video and audio can get separated when it gets encoded digitally or in a digital process stream.
The wobbliness you describe probably stems from a badly preserved analog tape. When the playback speed isn’t exaclty constant, the slowing down and accelerating causes the audio to change pitch, which is a lot more noticable in music than speech due to the more constant pitch of music. There is software to correct that, but it’s very expensive and hasn’t been around for long. Check out this video by the German company Celemony (who also brought us the revolutionary Melodyne technology).
Why does the video look so good? If the show was shot on film, all you have to do is scan it at a better resolution. This is why you can make a Blu-Ray from The Wizard Of Oz that looks absolutely amazing, even though the movie is 73 years old.
Colour me impressed. That is pretty good. If you have the original tape it is also possible to use the bias signal to remove wow and flutter, and rather importantly scrape flutter, which can result in a final result better than anyone had ever heard the recording. But that Capstan process will of course work with anything, not just an original tape, but something that has the wow and flutter baked into it from problems earlier in the flow.
According to IMDb, Law and Order was shot on 35mm film. So indeed, lots of very high quality visual capability there. It sounds as of they just didn’t take the time to get the sound right.
Part of it, too, might be wear and tear on the media itself. L&O has been in syndication forever, and that particular episode might have been shown many many times. If the video hasn’t been stored properly, that can also cause degradation.
Finally, it may also just be your TV. The sound on TV sets is better than it used to be, so audio that sounded OK on an older analog set may sound worse on a newer set.