The leftmost strip is Sony Dynamic Digital Sound, the square between the sprocket holes (which give you an idea just small these are) is Dolby Digital. Each barcode encodes all the different surround channels. Sadly no open source formats though, unless you consider the two analog waveforms on the right.
IDK, sorry and feel free to remove if this breaks the community rules, I just thought it was really cool. I've always just assumed they had a separate medium for storing the sound and just timed them to play in sync.
My novice take: the waveforms on the right are sufficient to recreate analog stereo.
Digital audio signals are fundamentally represented by a series of numbers with a frequency corresponding to a fixed sample rate. For example: 16-bit unsigned integers at 44.1kHz. Each number is a sample and represents only a magnitude/intensity in time, forming a time domain waveform. Tones and pitches, and everything else one can hear are represented by these numbers in varying arrangements. Check out the waveform for a sine or triangle tone: the waveforms literally depict those shapes.
The optical analog waveform is encoding the same information as the sampled digital one described above. I'm not sure of the mechanism by which an optical system translates the analog waveform into sound, however.