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Cake day: June 10th, 2023

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  • By your definition, PNG isn’t lossless because it’s not an exact representation of every single photon of a picture that was taken. You’d need infinity pixels in order to be completely faithful to the “analog” thing that you’re trying to picture, in the same way you’d need infinity points to completely translate an analog wave to digital.

    When you compress anything with FLAC, you will get the exact same thing you compressed out, so there is no data loss.

    Of course, that wave which you compress will not be faithful to the analog thing, but that’s just a limitation of digital computers.



  • When we talk about lossless in the audio encoding world, we aren’t comparing directly with the analog wave, as there will always be loss when storing an analog signal in a digital machine. Lossless formats are compared to pure PCM, which is the uncompressed way of representing a waveform in bits.

    With audio, every step you take to transform it, capture it, move it or store it, even while working with the analog waveform, degrades it. Even by picking it up with a microphone you’re already degrading the waveform. However, generally, the official release CDs or WebDLs are considered the original, lossless, master file. Everything that manages to keep that exact waveform is lossless (FLAC, AIFF, WAV, ALAC…), and everything that distorts it further is considered lossy (MP3, AAC, OPUS…).

    Additionally, a “bad transcode” (which is a transcode that involves lossy formats somewhere that isn’t the last step) is also considered lossy, for obvious reason. Transcoding FLAC to MP3 to WAV stores the exact same waveform that MP3 made, as it is the lowest common denominator, even though the audio is stored as WAV in its final form.

    Transcoding between lossy formats also loses more data, even if the final lossy format can store more bits or is more accurate than the original. This is one of the main problems with lossy codecs. MP3 192kbps to MP3 320kbps will lose information, just like MP3 to AAC. That’s why, normally, we use a lossless file and transcode it to every lossy format (FLAC to MP3, then FLAC to AAC…). This way you’re not losing more than what the lossy format already loses.