Once upon a time everyone knew who was No. 1. My mates, my Mum and probably your Mum too - knew if Blur had beaten Oasis, and whether the Spice Girls had managed to get their sixth chart topper in a row.

Now that's no longer the case. Unless it's the Christmas No. 1, with its attendant media hoopla, the specifics of who exactly is heading the charts often passes us by.

The reasons for this are legion. The popularity of 'the illegal download' meant that by 2003 the correlation between sales and audience consumption was weakened. Then the high street record shop evaporated, music TV moved from sales related rundowns to arbitrary lists of loosely themed hits and most recently the ever fluctuating musical barometer of the iTunes chart has added to the confusion.

Radio 1's flagship Top 40 used to open with a jingle that announced it was "The Only Chart That Counts". As well as being a pleasing pun, it was true, but as ever greater confusion reigned over which radio, TV or digital chart represented 'the real' Top 40, that claim became harder to justify.

The Official Chart has always remained the gold standard of chart programming of course - and the only show on which being declared No. 1 gets you an entry in the history books. However, with young music fans able to pull up the number one video in a fresh browser window in the time it takes the presenter to introduce the track, the battle for relevance has become ever more acute. The battlefield for the chart? The web. And as everyone knows you don't go into a digital fight armed only with good sound; you need vision.

The chart is exciting, it's about celebrating pop music and new music and visualising the show will ensure the chart is relevant to younger audiences.

This Sunday at 6pm Reggie Yates will become the first Radio 1 presenter to play not a record, CD, or Wav, but a DVD. Listeners will be able to enjoy a similar show to the one they have known and loved, but the millions of teens who are online at that time of day will also be able to watch Reggie, his guests, the latest music news as it breaks, and the videos of the ten best-selling singles. If pop can be compared to football then it's Reggie who is blowing the final whistle, and doing so whilst presiding over the videprinter as the scores come in.

We are not making a TV show. We are making visual radio which makes the most of what we already do on air, whilst giving new young audiences the content they want on the platform they want it on. The tickers, astons and graphics will not try to emulate or compete with music television, but will add to enhance the visual just as Reggie enhances the audio.

It represents not just the way that the chart needs to go to, but also the direction that radio needs to move in to maintain its stature.

Radio needs a visual if it's going to reach young people on their second favourite search engine, YouTube. Views of Radio 1's live lounge performances frequently outstrip the numbers that listened live, whilst 1Xtra's hip-hop phenomenon Charlie Sloth films freestyles during his show some of them have been watched by a hundred times more people than heard the programme.

So this Sunday, when Reggie proudly presses play on his Pioneer DVJ for the first time, it is the start of something you'll be hearing - and seeing - a great deal more of from radio stations around the world. For millions of young music fans The Official Chart with Reggie Yates will be, in more ways than ever before, the only chart that counts.

You can listen to The Official Chart with Reggie Yates on BBC Radio 1 4-7pm every Sunday

You can watch the final hour of The Official Chart with Reggie Yates at bbc.co.ukradio1 6-7pm every Sunday