[FFmpeg-user] Audio captured via AVFoundation is unusable

[Gabriel Balaich]

> Would whoever wrote that actually identify themselves in their email?
> That would be quite helpful (as well as courteous).

Apologies, I've updated the name attached to this email, and will sign all messages moving forward. I created a custom email with my domain for use with this mailing list.

Just now I clean installed macOS on my MacBook Pro w/ M3 Pro:
ninbura at ninburas-MacBook-Pro bin % stat -f "%SB" /Users/$(whoami)
Jun 15 12:59:58 2025

ninbura at ninburas-MacBook-Pro bin % ls -l /var/db/.AppleSetupDone
-r--------  1 root  wheel  0 Jun 15 13:00 /var/db/.AppleSetupDone


I then created an FFmpeg build that required no dependencies, played a song out on my studio monitors, and recorded audio using the mic built into the MacBook:
./ffmpeg -y \
  -thread_queue_size 9999 \
  -indexmem 9999 \
  -f avfoundation \
  -i ":MacBook Pro Microphone" \
  -c:a pcm_f32le \
  -ar 48000 \
  -ac 2 \
  -vn \
  ~/Movies/2025-06-15_static_clean-installed-macOS-avfoundation-test.wav

The result is the same, glitchy/crackling pitch shifted audio:
https://drive.proton.me/urls/T664MFK464#fYI0HqeRciQL

I used iMessage and a USB drive to transfer commands and files between my Mac Studio and MacBook Pro, without installing any additional software. I never connected a dock or even the charger, only a USB drive to transfer the binaries & output files. Seeing as I have now tested 2 unique systems, one of which has zero 3rd party modifications, and various FFmpeg builds; I believe I have adequately demonstrated that the issue is not caused by some component in my setup.

After I ran the initial test with said static build of FFmpeg, I once again installed FFmpeg via brew, and built a more comprehensive binary. I tested with all said builds on the clean system, the result is always the same.

Full output:
ffmpeg version N-119886-g52441bd4cd Copyright (c) 2000-2025 the FFmpeg developers
  built with Apple clang version 17.0.0 (clang-1700.0.13.5)
  configuration: --prefix=/Users/ninbura/ffmpeg/builds/ffmpeg-master-static-20250615-13-51-56 --cc=/usr/bin/clang --enable-static --disable-shared --disable-autodetect --enable-pthreads --enable-version3 --enable-gpl --disable-ffplay --disable-network --disable-protocols --enable-protocol=file --enable-protocol=pipe --enable-audiotoolbox --enable-videotoolbox --enable-avfoundation --enable-neon --disable-debug --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-xlib --disable-zlib --disable-bzlib --disable-lzma --disable-iconv --extra-cflags= --extra-ldflags='-Wl,-ld_classic'
  libavutil      60.  3.100 / 60.  3.100
  libavcodec     62.  3.101 / 62.  3.101
  libavformat    62.  1.100 / 62.  1.100
  libavdevice    62.  0.100 / 62.  0.100
  libavfilter    11.  0.100 / 11.  0.100
  libswscale      9.  0.100 /  9.  0.100
  libswresample   6.  0.100 /  6.  0.100
2025-06-15 14:01:29.164 ffmpeg[17181:104662] WARNING: Add NSCameraUseContinuityCameraDeviceType to your Info.plist to use AVCaptureDeviceTypeContinuityCamera.
Input #0, avfoundation, from ':MacBook Pro Microphone':
  Duration: N/A, start: 3830.523354, bitrate: 1536 kb/s
  Stream #0:0: Audio: pcm_f32le, 48000 Hz, mono, flt, 1536 kb/s, Start 3830.523354
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_f32le (native) -> pcm_f32le (native))
Press [q] to stop, [?] for help
Output #0, wav, to '/Users/ninbura/Movies/2025-06-15_static_clean-installed-macOS-avfoundation-test.wav':
  Metadata:
    ISFT            : Lavf62.1.100
  Stream #0:0: Audio: pcm_f32le ([3][0][0][0] / 0x0003), 48000 Hz, stereo, flt, 3072 kb/s
    Metadata:
      encoder         : Lavc62.3.101 pcm_f32le
[out#0/wav @ 0x600002ba0480] video:0KiB audio:15260KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.000589%
size=   15260KiB time=00:00:45.56 bitrate=2743.4kbits/s speed=   1x elapsed=0:00:45.57    
Exiting normally, received signal 2.

Thanks, Gabriel.