问题
I'm following the python challenge riddles, and I now need to analyse a wav file. I learn there is a python module that reads the frames, and that these frames are 16bit or 8bit.
What I don't understand, is what does this bits represent? Are these values directly transformed to a voltage applied to the speakers (say via factoring)?
回答1:
The bits represent the voltage level of an electrical waveform at a specific moment in time.
To convert the electrical representation of a sound wave (an analog signal) into digital data, you sample the waveform at regular intervals, like this:
Each of the blue dots indicates the value of a four-bit number that represents the height of the analog signal at that point in time (the X axis being time, and the Y axis being voltage).
In .WAV files, these points are represented by 8-bit numbers (having 256 different possible values) or 16 bit numbers (having 65536 different possible values). The more bits you have in each number, the greater the accuracy of your digital sampling.
回答2:
WAV files can actually contain all sorts of things, but it is most typically linear pulse-code modulation (LPCM). Each frame contains a sample for each channel. If you're dealing with a mono file, then each frame is a single sample. The sample rate specifies how many samples per second there are per channel. CD-quality audio is 16-bit samples taken 44,100 times per second.
These samples are actually measuring the pressure level for that point in time. Imagine a speaker compressing air in front of it to create sound, vibrating back and forth. For this example, you can equate the sample level to the position of the speaker cone.
来源：https://stackoverflow.com/questions/25940376/whats-the-actual-data-in-a-wav-file