How would I view the waveform of an SFK file without the source file?

sindexmon-1172 wrote on 6/10/2024, 11:17 PM

Hi; to cut to the chase, I have an SFK file that contains the waveform data of a long-deleted audio recording that means a lot to me. With the detail provided by that file, I could technically reconstruct it.

I have tried multiple versions of both VEGAS and SOUND FORGE, but there is no straight-forward method to opening the file without the exact (bit-perfect?) source, and no work-around seems to work.

Is there another product that could solve my problem? If not, is there another way I could interpret the data?

Thank you.


SP. wrote on 6/11/2024, 5:28 AM

@sindexmon-1172 sfk files only contain the graphical waveform peak data, no audio data. Maybe you still have a proxy file (file type is sfap0)?

Otherwise you might try a data recovery software if you just recently lost the file.

sindexmon-1172 wrote on 6/11/2024, 12:42 PM

Thanks for the reply; unfortunately I don't have a proxy file. It is still theoretically possible to reconstruct audio with a detailed enough waveform, though. I would heavily appreciate if there's some way to view an SFK file as a waveform, or interpret it in some way.

SP. wrote on 6/11/2024, 1:03 PM

@sindexmon-1172 Judging by the Sfk files on my computer, if you can find a way to get the Wav file out of the Sfk file, you have found a way to compress a Wav file losslessly by around 99.98%. With Flac compression I usually get about 25%.

sindexmon-1172 wrote on 6/11/2024, 2:48 PM

Ohh it's not lossless by any means. Best case scenario, it'll resemble a recording from the 40s. Still worth a try, though.

johnebaker wrote on 6/11/2024, 3:16 PM



. . . . It is still theoretically possible to reconstruct audio with a detailed enough waveform, though. . . . .

In theory this is possible, however, as I understand the reversal process, there are 2 problems here:

The waveform, as @SP. has alluded to, is missing a significant amount of data, the SFK file only contains ~0.2% of the required data for the Inverse FFT calculations necessary to reconstruct the waveform. This alone removes any possibility of reconstructing the audio file in a meaningful manner.

Additionally, if I am reading the Inverse FFT formula correctly, the calculations also require time domain related phase data, which you do not have.

I assume you, nor anyone else who had the audio file, have backups of the original audio anywhere.

John EB

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sindexmon-1172 wrote on 6/11/2024, 4:51 PM


Thank you so much for the explanation; I'm obviously not an audio engineer by any means.

I'm still curious if there's any way to view the waveform, though, mainly just to get a sense of how the audio played out. I know the time of the video, if that isn't already held in the SFK file, but that's about it.

rraud wrote on 6/15/2024, 10:12 AM

The <.sfk> is to facilitate to fast opening the main media file, which could be slow in absence of the sfk waveform file, depending on the length and other factors. AFAIK, the file is useless w/o the companion media file.