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Comment by fernly | Hacker News Reader

Seems like it should be technically feasible to capture the bits of a streamed song. Are there rogue players that can divert the content to a file?

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I would hope that such a solution doesn't just rip the PCM. If the source isn't lossless and you do it that way, you'll likely be encoding lossy twice.

PCM is a legacy format, not terribly advanced (poor encoding for space used) and very vulnerable to faults. Hacked Pandora (Unlimited skips, no ads, thumbs upping a song prompts to save it, runs on Android) saves all music files as whatever format Pandora sent them as, with no transcoding.

What they were asking was whether the files would be saved before being decoded to raw audio samples (i.e. PCM data) or if they'd be captured during decoding.

PCM isn't "a legacy format". It's the stream of data as it exists right before hitting the DAC.

Ah, I'm not terribly familiar with DACs, I mainly see PCM in phones for audio files and paging applications, which seems really silly considering these phones support much more efficient codecs like Opus.

PCM is uncompressed audio. I'm not sure what you mean by "legacy" or "vulnerable to faults" but every decoder you are using is spitting out PCM for handing it to the sound card.

What I'm saying is you want something like what you describe as "hacked pandora" to get the bits before decoding.

Otherwise you're doing the audio equivalent of JPEG -> BMP -> JPEG (to make a visual metaphor).

Hacked Pandora is a thing, and it just grabs the initial file, no transcoding. http://www.apktron.com/2016/02/pandora-69-unlimited-skips-no...

On the Mac, Audio Hijack does a good job of recording whatever is playing through your computer. It's useful for recording Skype calls for podcasts, for instance.

https://rogueamoeba.com/audiohijack/

Soundflower can divert audio: https://github.com/mattingalls/Soundflower/releases/

iTunes will happily stream Apple Music to an AirPlay device, and AirPlay is unencrypted ALAC.

Alternatively simply play through a digital audio output and capture it that way.

>Alternatively simply play through a digital audio output and capture it that way.

You have no way of knowing what the data's original quality is at, and its introducing artifacts from analog output back into a digital form, which is then outputted to analog again. Its an option, sure, but its like saying "get all your music on youtube."

They are suggesting going digital-out (on the source) to digital-in. No analog.

But as pointed out Audio Hijack does the same thing virtually with a kernel extension.

You misunderstood. I said digital capturing the digital audio output.

  >and AirPlay is unencrypted ALAC.

That won't last. And with the removal of the headphone jack, we lose our last analog (and unencrypted) path for capturing audio.

The dongle works.

headphone jacks give a pretty crisp signal :)

You have a headphone jack on your phone? My computer still has one, but not for long I assume.

Don't most of the jackless phones have an external DAC dongle or something? Audio jack on a computer is something I've just assumed for...almost 25 years, at this point. I guess I'll have to remember to start keeping an eye out for it, make sure it's still there next time I need a new machine.

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