Combine existing audio files and generate new audio file from them

Question

I have 2 sample wavfiles.

I would like to combine them into one output wav like this:

Play first wav, wait x seconds play 2nd wav, and save the results as a new wav file.

I'm not particularly attached to the wav format, so happy to use another if necessary.

From my research it looks like I would need to convert the wavs to PCM, and then create a new output buffer and write the first file the output buffer. Then somehow create a space for the x seconds, and then write the second PCM to

How would I go about doing this?

Answer 1

First of all you'll need to undestand what you are talking about

WAV is a type of RIFF which encodes the sound waves as PCM.

Essentially PCM means that discrete values of the wave are stored at a certain sample rate (typically 44 kHz)

Each sample may contain information about one or more channels (typically 2)

The values of each sample are stored as a fixed size integer or float. (typically 16 bit integer)

These attributes are stored in the WAV header

To combine two seperate WAV files you need to read the header of both files and if you are lucky they will have the same ByteRate ( == samplerate * channel count * bits/sample / 8) then you simply need to concat the second file minus the header to the end of the first, and add the length of the second to the 'length' field of the first.

In any other case I advise you to utilize a library that does reencoding of some sort.

If you have the time and muse, you could do the recoding yourself.

If you don't want to bother with this stuff at all try using a complete program (i.E. sox) that does what you need.

Btw.: Silence is 0 values if this bits per sample are signed and half of the max value if they are unsigned (typically only found in 8 bit integers).

So to get 4 seconds of silence you need to have n = 4 * sample rate * channel num * (bits / seconds) / 8 times 0

Trivia: You could use any constant value instead of 0 for silence