I can confirm this is working on a Google Pixel 4 w/ Magisk root. I spent some time playing with the various settings and it seems the defaults are close (or very close) to optimal. The recording quality is so-so when recorded via the handset. Conversations are understandable but both sides of the call sound like they are being recorded in a bit of an echo chamber; kind of like what you would hear if you listened to a recording of music playing from a speaker.
A huge plus is that this works out of the box for recording over a Bluetooth headset. And with the headset, quality is significantly improved, but the trade-off is that volume is much lower. This can be managed by increasing the record volume in the settings to 200 or even 400%. This improves the volume of BT conversations but adds so much distortion to handset recordings that they are no longer usable. Small issues considering that this is the only app I know of that is working on a rooted Pixel 4.
I recorded short calls with various settings, formats, levels, etc, and found that the best in terms of quality was:
Audio Source: Voice call uplink + downlink
Recording Format: WAV
Sample rate: 16000 Hz
Volume: 50%, 100%, 200% (depending)
When BT connected: do nothing
Changing the format to MP3 had a noticeable drop in audio quality. It intensified the echo chamber feel. Unchecking the "Don't use AMR driver" (meaning the driver would be used), caused recordings to not function. The app gave me a notification warning on the next call and re-enabled the checkbox on its own. Nice!
Changing the audio source to "Voice Communication" produced call recordings with no sound on either side. Using "Unprocessed" and "Default" produced recordings with a greatly diminished volume on the called party side and a somewhat reduced volume on the phone owner side. Perhaps using one of these with a 200% or 400% increased volume will yield ok results, but I didn't test.
Interestingly, changing the recording method to "root" doesn't work. No matter which subtype I choose (CAF, ALSA, MSM) I would always get the "Call Recorder can't record this call" notification.
Open questions I'm hoping someone could answer:
With a rooted phone, is it safe to completely disable the app notification? I know on non-rooted devices, Android will kill background apps that don't have a notification icon, but my understanding is that with the Magisk path, the recording app runs as a system app and those can never be auto-killed.
I like the option to encrypt the recordings, but is there information on what type of encryption is used, and how I could decrypt the files using a different, off-phone tool?
Thanks for all the awesome work!
|call rec, call recording, callrec|
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