I knew it in the same way catcuddler did! Such a familiar tune, never bothered to learn who wrote it. Just remember the violin music, tried searching by rhythm and then by notes, nothing doing. Gave up after ages (musicpedia isn't the most reliable site, but I guess it's hard to get something like that working at all really), just thought it's got to be somewhere in the main violin pieces. Tried the "Top 50 Best Classical Violin Music" YouTube video, nothing there either... but wait, that Schön Rosmarin by (arranged by?) Kreisler sounds similar in style and playing, maybe this guy Kriesler's worth looking further into...
And there it was, 11 pieces and 33 minutes into "Kreisler: 2 hours of Perfection"! Had to check the composer but that was the easy bit.
I probably had it easier when I only had to track down some obscure physics calculation that it turns out was first done by a Russian scientist in the 1970s in defunct Soviet Journals, tbh.