Unable to get 120 fps out of 120 fps mode avfoundation camera

[bxff]

Description
When trying to get 120fps out of avfoundation native iOS camera by using -video_size 1920x1080 -framerate 120, the actual frame rate is approx ~70fps not 120fps, this is also the case with 240fps mode (-framerate 240), where the resultant fps is around ~120fps. This is not the case with 60fps mode, where I get full 60fps.

Expected behavior
Get 120fps on 120fps mode, and 240fps on 240fps mode.

Current behavior
Getting ~70fps on 120fps and ~120fps on 240fps mode.

To Reproduce
Run a simple ffmpegkit react native application a simple command similar to this: -f avfoundation -video_size 1920x1080 -framerate 120 -i "0" -fps_mode vfr -c:v hevc_videotoolbox -realtime true -profile 0 -prio_speed true -b:v 2000k f udp://192.168.1.100

Screenshots
No screenshots needed.

Logs

 LOG  ffmpeg version n5.1.2
 LOG   Copyright (c) 2000-2022 the FFmpeg developers
 LOG  
 LOG    built with Apple clang version 14.0.0 (clang-1400.0.29.102)
 LOG    configuration: --cross-prefix=arm64-ios-darwin- --sysroot=/Applications/Xcode-v13.4.1.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS16.0.sdk --prefix=/Users/taner/Projects/ffmpeg-kit/prebuilt/apple-ios-arm64/ffmpeg --pkg-config=/opt/homebrew/bin/pkg-config --enable-version3 --arch=aarch64 --cpu=armv8 --target-os=darwin --enable-neon --enable-asm --ar=/Applications/Xcode-v13.4.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar --cc=clang --cxx=clang++ --as='/Users/taner/Projects/ffmpeg-kit/.tmp/gas-preprocessor.pl -arch aarch64 -- clang -arch arm64 -target arm64-apple-ios12.1 -march=armv8-a+crc+crypto -mcpu=generic -DFFMPEG_KIT_ARM64 -Wno-unused-function -Wno-deprecated-declarations -fstrict-aliasing -fembed-bitcode -DIOS -DFFMPEG_KIT_BUILD_DATE=20220929 -isysroot /Applications/Xcode-v13.4.1.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS16.0.sdk -Oz -miphoneos-version-min=12.1 -I/Applications/Xcode-v13.4.1.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS16.0.sdk/usr/include' --ranlib=/Applications/Xcode-v13.4.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib --strip=/Applications/Xcode-v13.4.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/strip --nm=/Applications/Xcode-v13.4.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm --extra-ldflags='-miphoneos-version-min=12.1' --disable-autodetect --enable-cross-compile --enable-pic --enable-inline-asm --enable-optimizations --enable-swscale --enable-shared --disable-static --install-name-dir='@rpath' --enable-pthreads --disable-v4l2-m2m --disable-outdev=v4l2 --disable-outdev=fbdev --disable-indev=v4l2 --disable-indev=fbdev --enable-small --disable-xmm-clobber-test --disable-debug --disable-neon-clobber-test --disable-programs --disable-postproc --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-sndio --disable-schannel --disable-securetransport --disable-xlib --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --disable-alsa --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --enable-gmp --enable-gnutls --disable-sdl2 --disable-openssl --enable-zlib --enable-audiotoolbox --disable-outdev=audiotoolbox --enable-bzlib --enable-videotoolbox --enable-avfoundation --enable-iconv --disable-coreimage --disable-appkit --disable-opencl --disable-opengl
 LOG    libavutil      57. 28.100 / 57. 28.100
 LOG    libavcodec     59. 37.100 / 59. 37.100
 LOG    libavformat    59. 27.100 / 59. 27.100
 LOG    libavdevice    59.  7.100 / 59.  7.100
 LOG    libavfilter     8. 44.100 /  8. 44.100
 LOG    libswscale      6.  7.100 /  6.  7.100
 LOG    libswresample   4.  7.100 /  4.  7.100
 LOG  [avfoundation @ 0x11c32de00] Selected pixel format (yuv420p) is not supported by the input device.
 LOG  [avfoundation @ 0x11c32de00] Supported pixel formats:
 LOG  [avfoundation @ 0x11c32de00]   nv12
 LOG  [avfoundation @ 0x11c32de00]   bgr0
 LOG  [avfoundation @ 0x11c32de00] Overriding selected pixel format to use nv12 instead.
 LOG  [avfoundation @ 0x11c32de00] Stream #0: not enough frames to estimate rate; consider increasing probesize
 LOG  Input #0, avfoundation, from '0':
 LOG    Duration:
 LOG  N/A
 LOG  , start:
 LOG  63627.813000
 LOG  , bitrate:
 LOG  N/A
 LOG  
 LOG    Stream #0:0
 LOG  : Video: rawvideo, 1 reference frame (NV12 / 0x3231564E), nv12, 1920x1080, 0/1
 LOG  ,
 LOG  1000k tbr,
 LOG  1000k tbn
 LOG  
 LOG  Please use -profile:a or -profile:v, -profile is ambiguous
 LOG  Stream mapping:
 LOG    Stream #0:0 -> #0:0
 LOG   (rawvideo (native) -> hevc (hevc_videotoolbox))
 LOG  
 LOG  Press [q] to stop, [?] for help
 LOG  Output #0, rtp, to 'udp://192.168.0.102:5000':
 LOG    Metadata:
 LOG      encoder         :
 LOG  Lavf59.27.100
 LOG  
 LOG    Stream #0:0
 LOG  : Video: hevc, 1 reference frame, nv12(progressive), 1920x1080 (0x0), 0/1, q=2-31, 200 kb/s
 LOG  ,
 LOG  120 fps,
 LOG  90k tbn
 LOG  
 LOG      Metadata:
 LOG        encoder         :
 LOG  Lavc59.37.100 hevc_videotoolbox
 LOG  
 LOG  SDP:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 192.168.0.102
t=0 0
a=tool:libavformat LIBAVFORMAT_VERSION
m=video 0 RTP/AVP 96
b=AS:200
a=rtpmap:96 H265/90000
a=control:streamid=0
 LOG  [hevc_videotoolbox @ 0x150422c00] Color range not set for nv12. Using MPEG range.
 LOG  {}
 LOG  frame=    1 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x
 LOG  {}
 LOG  frame=   40 fps=0.0 q=-0.0 size=     156kB time=00:00:00.30 bitrate=4132.5kbits/s speed=0.612x
 LOG  {}
 LOG  frame=   77 fps= 76 q=-0.0 size=     273kB time=00:00:00.61 bitrate=3630.5kbits/s speed=0.609x
 LOG  {}
 LOG  frame=  110 fps= 73 q=-0.0 size=     363kB time=00:00:00.89 bitrate=3331.2kbits/s speed=0.588x
 LOG  {}
 LOG  frame=  142 fps= 70 q=-0.0 size=     473kB time=00:00:01.15 bitrate=3345.4kbits/s speed=0.574x
 LOG  {}
 LOG  frame=  176 fps= 70 q=-0.0 size=     583kB time=00:00:01.44 bitrate=3315.0kbits/s speed=0.57x
 LOG  {}
 LOG  frame=  207 fps= 68 q=-0.0 size=     691kB time=00:00:01.70 bitrate=3329.7kbits/s speed=0.56x
 LOG  {}
 LOG  frame=  243 fps= 69 q=-0.0 size=     805kB time=00:00:02.00 bitrate=3295.9kbits/s speed=0.565x
 LOG  {}
 LOG  frame=  277 fps= 68 q=-0.0 size=     983kB time=00:00:02.28 bitrate=3526.2kbits/s speed=0.564x
 LOG  {}
 LOG  frame=  310 fps= 68 q=-0.0 size=    1151kB time=00:00:02.55 bitrate=3685.9kbits/s speed=0.562x
 LOG  {}
 LOG  frame=  344 fps= 68 q=-0.0 size=    1319kB time=00:00:02.84 bitrate=3801.0kbits/s speed=0.562x
 LOG  {}
 LOG  frame=  377 fps= 68 q=-0.0 size=    1477kB time=00:00:03.11 bitrate=3882.7kbits/s speed=0.561x
 LOG  {}
 LOG  frame=  406 fps= 68 q=-0.0 Lsize=    1603kB time=00:00:03.37 bitrate=3891.4kbits/s speed=0.563x
 LOG  video:1587kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.031303%
 LOG  {}
 LOG  frame=  406 fps= 68 q=-0.0 Lsize=N/A time=00:00:03.37 bitrate=N/A speed=0.563x
 LOG  video:1587kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
 LOG  Exiting normally, received cancel request.
 LOG  Streaming was cancelled

Environment

• Platform: iOS/ReactNative
• Architecture: iPhone 14 Plus used.
• Version: brew version used
• Source branch: main
• Xcode version: 16.2
• Cocoapods version: 1.16.2
• react-native info: Run on a iPhone 14 Plus.