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I've got the audio bitdepth, frequency and channels down. Pretty simple to understand, but cannot find enough information on the different PCM formats.

I do understand the numbers correlate to the audio bitdepth.

The reason this matters is due to needing to preserve the audio that is above and below the range of human hearing from the extraction source.

Here are some options that were given:

PCM_ALAW

PCM_F32BE

PCM_F32LE

PCM_MULAW

PCM_S32BE

PCM_S32LE

PCM_U32BE

PCM_U32LE
Sea Maiden
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1 Answers1

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  • F – each sample stored as a floating point number
  • S – each sample stored as signed integer
  • U – each sample stored as unsigned integer

  • 16 – each sample takes 16 bits
  • 32 – each sample takes 32 bits

  • BE – each sample stored in big-endian format (endianness)
  • LE – each sample stored in little-endian format

The reason this matters is due to needing to preserve the audio that is above and below the range of human hearing from the extraction source.

If you're talking about frequencies above the range of human hearing then sampling frequency is the most important parameter for you. Take the highest frequency you want to preserve, drop everything above (see low-pass filter) and sample with twice the frequency. This procedure prevents aliasing.

Preserving of low frequency sounds ("below the range of human hearing") in theory comes easy because even poor sampling frequency will suffice.

Your hardware may have trouble registering or playing extreme frequencies though.

If "above and below the range of human hearing" is about loudness and quietness then you will need high dynamic range. In such case you may like floating point better than integer.

AFAIK signed vs unsigned and big-endian vs little-endian don't affect the quality of digital audio; i.e. you can convert from signed to unsigned without data loss, the same between big-endian and little-endian. These settings need to match between encoder and decoder.

Details of audio processing, of analog-to-digital conversion – are out of scope of Super User. Use the links I gave you to boost your research.

Kamil Maciorowski
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