Python Tutorial : Introduction to audio data in Python

Key Takeaways

hello and welcome to the course my name is Daniel Burke and I'll be your instructor to get started we're first going to see how speech and audio processing is different to other kinds of data processing much like other data types audio files come in many different formats such as mp3 wav m4a and flak but each of these formats has a standard measure of frequency frequency is measured in kilohertz but is also referred to as kHz or sampling rate much like how a movie shows 30 pitches per second which our brains register is moving pictures the sampling rate of an audio file is a measure of the number of data chunks per second used to represent a digital sound with one kilohertz equaling 1,000 pieces of information per second for example a song you stream will usually have a 32 kilohertz sampling rate this means 32,000 pieces of information per second speech and audiobooks are usually between 8 and 16 kilohertz we'll look at some of these later and as you might have guessed audio files are different to tabular or text data because you can't immediately see the data you're working with to get spoken language audio files into something we can see and manipulate we first have to open the audio file with pythons built-in WAV module we can get started with the WAV module by running the command import wave now we have an audio file goodmorning WAV ready to go it contains a person saying the words good morning to import it will use waves open method now we've saved the good morning WAV audio file to the variable good morning in the format of a wave object however in this state it's not very useful to us to manipulate a further will use the reframes method to convert the wave object the bytes the negative one means we want to read in all of the pieces of information within the wave object now we've converted the audio file to byte what do they look like okay we can see a snippet of the entire Sal wave in byte form but remember how kilohertz means thousands of pieces of information per second the good morning dot wav audio file is 48 kilohertz and 2 seconds long 48,000 pieces of information per second and 2 seconds long equals 96 thousand chunks of data all for only two words so if we printed out the entire Sal wave in byte form we'd see 96 thousand of these combinations of letters and numbers don't worry if the output looks confusing for now we'll learn how to convert these bytes into something more useful shortly now you can start to see how working with audio and spoken language files is different to other kinds of data first of all unlike text or tabular data you can't immediately see what you're working with so many audio files require a conversion step before you can begin working with them and because of the frequency measure even a few seconds of audio can contain large amounts of data add in background noise other sounds more speakers and the number of pieces of information grows even more we'll look into this later on alright it's