There isn't a direct relationship between "bits" in DSD and "samples" in PCM. They are related only through the analog waveform that they represent.

In PCM digital audio we represent the amplitude at a given point in time with a number. The time / amplitude value pair is called a "sample". The continuous analogue waveform is thus described by interpolation between sample values that are equally spaced in time, where the frequency of samples per second is the "sample rate".

In DSD (Direct Stream Digital) audio, there are no "samples", there is just a continuous stream of "bits". A "bit" is a "binary digit", which means that it is either an "on" state or an "off" state. The continuous analogue waveform is described by the "density" of "on" states. A continuous stream of zeros (off states) thus represents low voltage output, and a continuous stream of ones (on states) thus represents high voltage output. This is called "Pulse Density Modulation":

Here's an image to illustrate the scheme. Each vertical bar represents a "bit". If the "bit" is a "one" (an "on" state) it is shown in blue, and if "zero" ("off"), it is shown white. The red line represents the analogue waveform, that is "high" when the density of "ones" is greatest, and "low" when the density of "ones" is least.

- Pulse-density_modulation_2_periods.gif (3.06 KiB) Viewed 1437 times