How to know if a FLAC is a real FLAC?

Discussion in 'Audio Hardware' started by mickael57280, Aug 7, 2017.

  1. Rich1234

    Rich1234 New Member

    South carolina
    Download Spek.exe. It will show you if it is a true flac file.
    nosliw and patient_ot like this.
  2. Grant

    Grant A Musical Free-Spirit

    A high-bit lossy file over, say, 320 kbps, will not show any signs of being lossy if it is converted to a lossless container like FLAC. When you get up into the 400s, you have to start wondering how anal you are going to be about it.
  3. vinylontubes

    vinylontubes Forum Resident

    Katy, TX
    tuttle touched on this. No upsampling a file will fill the gaps with dithered data. So it also file size scales to the upsampling. JPEGs will do the same thing except with more subtlety with enlarging a photo, since the largest portion of a JPEG is palette. With dithering a JPEG, the palette increases because dithering by filling in a gradient between the pixels. This dithering occurs on the fly when playing lossy files. Upscaling hard codes the dither to new lossless file.
    stetsonic likes this.
  4. anorak2

    anorak2 Forum Resident

    Berlin, Germany
    320 kbps is the highest bitrate supported by the MP3 format :). Agree otherwhise.
  5. harby

    harby Forum Resident

    Portland, OR, USA
    Most of what you wrote here is a creative work of fiction. Not even layperson explanation, just wrong.

    JPEG does not have a palette map. It is a 24 bit format, 8 bits per color.
    JPEG does not "do the same thing", or really do anything, when you resize. Image manipulation software does the resizing, outside of the compression codec or container.
    There is no dithering in JPEG, because again, there is not a bigger bit depth being converted into a smaller bit depth.

    With psychoacoustic lossy codecs, there is also no "dithering" or "upscaling" or anything else you mention...

    Lossy codecs generally transform audio from the time domain into the frequency domain with FFT, at the same general data rate and quality as the source bitrate. Then they do analysis, using models of human hearing, to determine when certain frequencies are masked or inaudible. The bins of inaudible frequencies are then not encoded or stored in the lossy container if they are not contributing to the perceptible experience.

    When the lossy file is played back (decoded), it is simply turned back into the time domain with the non-encoded information not present. The output is still the same sampling rate and bit depth (although actually in MP3, the floating point numbers that store the audio can be decoded to 24 bit PCM for more accuracy).

    On medium-fidelity perceptually-encoded files, using frequency analysis with the correct windowing and small number of bins (like 1024 in this example) one of the tell-tale signs is the "grittiness" or "holes" that one can see in the spectral view:

    Or with more time resolution:

    Another sign is, if you use an extremely small number of bins for high temporal resolution, your view doesn't actually give more resolution, because the audio has already gone through a differently-sized FFT transformation.

    *highest bitrate reliably decoded by all general-purpose devices and decoders. It actually supports larger frames than 320kbps, and the data can be spread between frames with the frame buffer.
    Last edited: Dec 17, 2017
    vinylontubes likes this.
  6. libertycaps

    libertycaps Well-Known Member

    Portland, OR, USA
    Gods. Just buy the freaking used CD already! They are cheap and unimpeachable.
    SteelyNJ and TarnishedEars like this.
  7. patient_ot

    patient_ot Forum Resident

    That depends on what album you are talking about. Awhile back I wanted a particular album and the used, legit CD copies sell from $75-$100 because the album is OOP and in demand with certain types of collectors. I purchased the FLAC from the Tidal Store for $18. Of course I checked it with Spek as soon as I downloaded it, and luckily it was legit.

    Some of use also follow independent artists on Bandcamp. I made a thread awhile back detailing experiences where certain labels or artists that do not know better will upload lossy files to their store. Spek is also very useful in that case.
  8. Grant

    Grant A Musical Free-Spirit

    Yeah, I know. I was thinking of formats like AAC and Oog Vorbis, which go higher than mp3.
  9. fumi

    fumi Forum Resident

    This application runs on a Mac. It even tells you if the Flac file was upsampled. As you can see, it detects the bitrate on two tracks that don't match.

    Grant likes this.
  10. Grant

    Grant A Musical Free-Spirit

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