# Audio formats and CPU usage.



## Space Dynamics (Oct 31, 2020)

Hey friends!

I was wondering what the most processor intensive format is to play audio on. Would that be a super compressed flac file?

I want to do some experiments with some older computers and sound cards I have, and see if I can make any notable impact on performance with and without a dedicated audio processor.


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## CityCultivator (Oct 31, 2020)

FLAC decompression has a fixed cost independent on compression level. It can vary on bit rate and size, not on compression level.
Try WAVPack at high compression rate with high bit rate and size; it has a symmetric compression level where if you increase that level to high, it will also take as much CPU to decompress.
Most soundcards receive decompressed PCM, so is not affected by file format.
But for PC usage, most PC hardware will not be affected; audio decoding is often single digit % core usage.


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## Space Dynamics (Oct 31, 2020)

Thank you for the insight!


CityCultivator said:


> Most soundcards receive decompressed PCM, so is not affected by file format.


Could you elaborate on this? Or is there an article I can read to get a better understanding?


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## CityCultivator (Oct 31, 2020)

When you play a file, the file is decompressed. After decompression, you get usually PCM signal which will be resampled to below signal.
The final PCM signal is as configured in advanced audio endpoint settings. see below picture in spoiler where output signal is 24 bit 48KHz signal.
All audio coming from your PC will be mixed together then sent in this selected format to the sound card DAC (Digital to analog converter).
Modern soundcards do not do any decoding usually; they only are glorified DACs (and ADCs)


Spoiler


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