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Soundflower is usually used, but must be installed. Filmora srcn records system sound without installing drivers. How it captures the sound? MacOS, not iOS

Den
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1 Answers1

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I just took 5 minutes to download their dmg and root through the .app bundle. I found a "SystemAudioRecorder.kext", which appears to link against the various IOAudio* IOKit classes, so my guess would be via that. (It's inside a zip file: Wondershare Filmora Scrn.app/Contents/Resources/FSRecorder.app/Contents/Resources/SystemAudioRecorder.zip)

I suspect you probably won't be able to avoid writing a driver. IOAudio kexts are deprecated, so I don't especially recommend going that route. The simplest solution would probably be to implement a Core Audio Server plugin that acts as an audio output device. This will normally stop output to your system audio device however, which may or may not be what you want. (You don't specify.) You might be able to use metadevices to combine your recording device with the system audio - I haven't tested that approach, the last time I did anything like this, IOAudio wasn't deprecated yet. (And even then that was a pain to get right.) Perhaps a different type of audio plugin than a HAL plugin would work better, however.

In any case, this still requires admin access (and a reboot) to install the audio plugin, although it won't require a kext signing certificate, just a regular "Developer ID" cert.

Apple's NullAudio example code is probably the best starting point for audio server plugin development. (It's not a particularly well-documented corner of the OS.)

pmdj
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  • kernel extensions have a pretty high barrier to entry... I dont know that counts as a satisfactory answer... it may be the only way... but if that is the case the documentation for IOKit IOAudio stuff may be the better way to frame it. – Grady Player Oct 26 '18 at 14:25
  • @GradyPlayer The question was how the mentioned software records system audio without installing drivers. It would appear that it does in fact, install drivers (why else ship them?). I've written an audio capture driver many years ago (and more recently written regular audio device drivers) and yet I'm not convinced the IOKit IOAudio documentation would be terribly helpful. For one, IOAudio is obsolete. – pmdj Oct 26 '18 at 14:43
  • hm. My find: sudo find /Applications/Wondershare\ Filmora\ Scrn.app/ -type f -name "*.kext". But kext not found. Also, filmora not required root privilege for run (for install kext) and in system audio new devices not founded – Den Oct 26 '18 at 14:48
  • @Den It's inside a zip file, I've just added the path to it to my answer, along with a possible alternative route to take. – pmdj Oct 26 '18 at 14:51
  • good update +1... t – Grady Player Oct 27 '18 at 17:12
  • It's my fault, I was inattentive. I already had this driver installed, but there is no reference to Filmora in it. If you delete it from the driver folder, then after rebooting, a button appears in the Filmora settings for installing the driver. This requests administrator privileges. – Den Oct 29 '18 at 06:25
  • I already have a working application for recording sound from a microphone and speakers using soundflower. I was interested in the question why audio devices are not visible in the macos audio settings. Perhaps, the key is used kIOAudioEngineIsHiddenKey: https://lists.apple.com/archives/coreaudio-api/2012/Jun/msg00075.html There is a good selection of material on this topic: https://stackoverflow.com/questions/18443621/mac-os-x-virtual-audio-driver Thank you! – Den Oct 29 '18 at 06:25