audio_backend_buffer_desired_length = 19845;
````
Is triple the default for the ALSA backend and effectively solves the above issue with a Pi Zero on a busy network.
+
+### AAC Decoder Issues (AirPlay 2 only)
+
+To play AirPlay 2 Buffered Audio streams, Shairport Sync needs an AAC decoder capable of decoding Floating Planar -- `fltp` -- AAC material. Unfortunately, not all systems have such a decoder. The idea here is to use the `ffmpeg` app to list AAC decoders and to check that the default AAC decoder has `fplp` capability. Here is an example of where the AAC decoder _can_ decode `fltp` material. The system is a Raspberry Pi running 64-bit Raspberry Pi OS Lite 11 (Bullseye):
+```
+$ ffmpeg -decoders | grep -i aac
+
+ffmpeg version 4.3.4-0+deb11u1+rpt1 Copyright (c) 2000-2021 the FFmpeg developers
+ built with gcc 10 (Raspbian 10.2.1-6+rpi1)
+ configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared --libdir=/usr/lib/arm-linux-gnueabihf --cpu=arm1176jzf-s --arch=arm
+ WARNING: library configuration mismatch
+ avutil configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avcodec configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avformat configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avdevice configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avfilter configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avresample configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ swscale configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ swresample configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ postproc configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ libavutil 56. 51.100 / 56. 51.100
+ libavcodec 58. 91.100 / 58. 91.100
+ libavformat 58. 45.100 / 58. 45.100
+ libavdevice 58. 10.100 / 58. 10.100
+ libavfilter 7. 85.100 / 7. 85.100
+ libavresample 4. 0. 0 / 4. 0. 0
+ libswscale 5. 7.100 / 5. 7.100
+ libswresample 3. 7.100 / 3. 7.100
+ libpostproc 55. 7.100 / 55. 7.100
+ A....D aac AAC (Advanced Audio Coding)
+ A....D aac_fixed AAC (Advanced Audio Coding) (codec aac)
+ A....D aac_latm AAC LATM (Advanced Audio Coding LATM syntax)
+```
+At the bottom you can see three decoders. The first one, called `aac`, is the decoder chosen by Shairport Sync. Checking its capabilities:
+
+```
+$ ffmpeg -h decoder=aac
+ffmpeg version 4.3.4-0+deb11u1+rpt1 Copyright (c) 2000-2021 the FFmpeg developers
+ built with gcc 10 (Raspbian 10.2.1-6+rpi1)
+ configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared --libdir=/usr/lib/arm-linux-gnueabihf --cpu=arm1176jzf-s --arch=arm
+ WARNING: library configuration mismatch
+ avutil configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avcodec configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avformat configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avdevice configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avfilter configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ avresample configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ swscale configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ swresample configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ postproc configuration: --prefix=/usr --extra-version=0+deb11u1+rpt1 --toolchain=hardened --incdir=/usr/include/arm-linux-gnueabihf --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-mmal --enable-neon --enable-rpi --enable-v4l2-request --enable-libudev --enable-epoxy --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --libdir=/usr/lib/arm-linux-gnueabihf/neon/vfp --cpu=cortex-a7 --arch=armv6t2 --disable-thumb --enable-shared --disable-doc --disable-programs
+ libavutil 56. 51.100 / 56. 51.100
+ libavcodec 58. 91.100 / 58. 91.100
+ libavformat 58. 45.100 / 58. 45.100
+ libavdevice 58. 10.100 / 58. 10.100
+ libavfilter 7. 85.100 / 7. 85.100
+ libavresample 4. 0. 0 / 4. 0. 0
+ libswscale 5. 7.100 / 5. 7.100
+ libswresample 3. 7.100 / 3. 7.100
+ libpostproc 55. 7.100 / 55. 7.100
+Decoder aac [AAC (Advanced Audio Coding)]:
+ General capabilities: dr1 chconf
+ Threading capabilities: none
+ Supported sample formats: fltp
+ Supported channel layouts: mono stereo 3.0 4.0 5.0 5.1 7.1(wide)
+AAC decoder AVOptions:
+ -dual_mono_mode <int> .D..A..... Select the channel to decode for dual mono (from -1 to 2) (default auto)
+ auto -1 .D..A..... autoselection
+ main 1 .D..A..... Select Main/Left channel
+ sub 2 .D..A..... Select Sub/Right channel
+ both 0 .D..A..... Select both channels
+```
+You can see the line:
+```
+Supported sample formats: fltp
+```
+towards the bottom. This means that the AAC decoder is suitable for use by Shairport Sync
+
+Here are the same commands, performed on Fedora 36, which, by default, does not support `fltp` decoding:
+```
+$ ffmpeg -decoders | grep -i aac
+ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers
+ built with gcc 12 (GCC)
+ configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' --extra-ldflags='-Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1 -Wl,-dT,/builddir/build/BUILD/ffmpeg-5.0.1/.package_note-ffmpeg-5.0.1-6.fc36.x86_64.ld' --disable-htmlpages --enable-pic --disable-stripping --enable-shared --disable-static --enable-gpl --enable-version3 --enable-libsmbclient --disable-openssl --enable-bzlib --enable-frei0r --enable-chromaprint --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libshaderc --enable-vulkan --disable-cuda-sdk --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libdc1394 --enable-libdrm --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libilbc --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libmysofa --enable-libopenh264-dlopen --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-librubberband --enable-libsnappy --enable-libsvtav1 --enable-libsoxr --enable-libspeex --enable-libssh --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libwebp --enable-libxml2 --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lto --enable-libmfx --enable-vaapi --enable-vdpau --enable-openal --enable-opencl --enable-opengl --enable-pthreads --enable-vapoursynth --enable-muxers --enable-demuxers --enable-hwaccels --disable-encoders --disable-decoders --disable-decoder='mpeg4,h263,h264,hevc,vc1' --enable-encoder=',libfdk_aac,ac3,apng,ass,ayuv,bmp,ffv1,ffvhuff,flac,gif,h263_v4l2m2m,h264_amf,h264_nvenc,h264_qsv,h264_v4l2m2m,h264_vaapi,hevc_amf,hevc_nvenc,hevc_qsv,hevc_v4l2m2m,hevc_vaapi,huffyuv,ilbc,jpegls,jpeg2000,libaom,libaom_av1,libcodec2,libgsm,libilbc,libmp3lame,libopenh264,libopenjpeg,libopus,librav1e,libschroedinger,libspeex,libsvtav1,libtheora,libtwolame,libvorbis,libvpx_vp8,libvpx_vp9,libwebp,libwebp_anim,mjpeg,mjpeg_qsv,mjpeg_vaapi,mp2,mp2fixed,mpeg1video,mpeg2video,mpeg2_qsv,mpeg2_vaapi,mpeg4_v4l2m2m,opus,pam,pbm,pcm_alaw,pcm_f32be,pcm_f32le,pcm_f64be,pcm_f64le,pcm_mulaw,pcm_s16be,pcm_s16be_planar,pcm_s16le,pcm_s16le_planar,pcm_s24be,pcm_s24le,pcm_s24le_planar,pcm_s32be,pcm_s32le,pcm_s32le_planar,pcm_s8,pcm_s8_planar,pcm_u16be,pcm_u16le,pcm_u24be,pcm_u24le,pcm_u32be,pcm_u32le,pcm_u8,pcx,pgm,pgmyuv,png,ppm,rawvideo,sgi,srt,ssa,sunrast,targa,text,tiff,v210,v308,v408,v410,vc1_qsv,vc1_v4l2m2m,vorbis,vp8_qsv,vp8_v4l2m2m,vp8_vaapi,vp9_qsv,vp9_vaapi,webvtt,wrapped_avframe,xbm,xwd,y41p,yuv4,zlib,' --enable-decoder=',libfdk_aac,ac3,ansi,apng,ass,av1_qsv,ayuv,bmp,dirac,exr,ffv1,ffvhuff,ffwavesynth,flac,gif,gsm,huffyuv,ilbc,jpeg2000,libaom,libaom_av1,libcodec2,libdav1d,libgsm,libilbc,libopenh264,libopenjpeg,libopus,libschroedinger,libspeex,libvorbis,libvpx_vp8,libvpx_vp9,mjpeg,mjpeg_qsv,mp1,mp1float,mp2,mp2float,mp3,mp3float,mpeg1video,mpeg1_v4l2m2m,mpeg2video,mpeg2_qsv,mpeg2_v4l2m2m,opus,pam,pbm,pcm_alaw,pcm_bluray,pcm_dvd,pcm_f32be,pcm_f32le,pcm_f64be,pcm_f64le,pcm_mulaw,pcm_s16be,pcm_s16be_planar,pcm_s16le,pcm_s16le_planar,pcm_s24be,pcm_s24le,pcm_s24le_planar,pcm_s32be,pcm_s32le,pcm_s32le_planar,pcm_s8,pcm_s8_planar,pcm_u16be,pcm_u16le,pcm_u24be,pcm_u24le,pcm_u32be,pcm_u32le,pcm_u8,pcx,pgm,pgmyuv,pgssub,pgx,png,ppm,rawvideo,sgi,srt,ssa,sunrast,targa,text,theora,tiff,v210,v210x,v308,v408,v410,vorbis,vp3,vp5,vp6,vp6a,vp6f,vp8,vp8_qsv,vp8_v4l2m2m,vp9,vp9_qsv,vp9_v4l2m2m,webp,webvtt,wrapped_avframe,xbm,xwd,y41p,yuv4,zlib,'
+ libavutil 57. 17.100 / 57. 17.100
+ libavcodec 59. 18.100 / 59. 18.100
+ libavformat 59. 16.100 / 59. 16.100
+ libavdevice 59. 4.100 / 59. 4.100
+ libavfilter 8. 24.100 / 8. 24.100
+ libswscale 6. 4.100 / 6. 4.100
+ libswresample 4. 3.100 / 4. 3.100
+ libpostproc 56. 3.100 / 56. 3.100
+ A....D libfdk_aac Fraunhofer FDK AAC (codec aac)
+```
+As you can see just one AAC decoder in available, the `Fraunhofer FDK AAC`. Examining it more closely:
+```
+$ ffmpeg -h decoder=aac
+ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers
+ built with gcc 12 (GCC)
+ configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' --extra-ldflags='-Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1 -Wl,-dT,/builddir/build/BUILD/ffmpeg-5.0.1/.package_note-ffmpeg-5.0.1-6.fc36.x86_64.ld' --disable-htmlpages --enable-pic --disable-stripping --enable-shared --disable-static --enable-gpl --enable-version3 --enable-libsmbclient --disable-openssl --enable-bzlib --enable-frei0r --enable-chromaprint --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libshaderc --enable-vulkan --disable-cuda-sdk --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libdc1394 --enable-libdrm --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libilbc --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libmysofa --enable-libopenh264-dlopen --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-librubberband --enable-libsnappy --enable-libsvtav1 --enable-libsoxr --enable-libspeex --enable-libssh --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libwebp --enable-libxml2 --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lto --enable-libmfx --enable-vaapi --enable-vdpau --enable-openal --enable-opencl --enable-opengl --enable-pthreads --enable-vapoursynth --enable-muxers --enable-demuxers --enable-hwaccels --disable-encoders --disable-decoders --disable-decoder='mpeg4,h263,h264,hevc,vc1' --enable-encoder=',libfdk_aac,ac3,apng,ass,ayuv,bmp,ffv1,ffvhuff,flac,gif,h263_v4l2m2m,h264_amf,h264_nvenc,h264_qsv,h264_v4l2m2m,h264_vaapi,hevc_amf,hevc_nvenc,hevc_qsv,hevc_v4l2m2m,hevc_vaapi,huffyuv,ilbc,jpegls,jpeg2000,libaom,libaom_av1,libcodec2,libgsm,libilbc,libmp3lame,libopenh264,libopenjpeg,libopus,librav1e,libschroedinger,libspeex,libsvtav1,libtheora,libtwolame,libvorbis,libvpx_vp8,libvpx_vp9,libwebp,libwebp_anim,mjpeg,mjpeg_qsv,mjpeg_vaapi,mp2,mp2fixed,mpeg1video,mpeg2video,mpeg2_qsv,mpeg2_vaapi,mpeg4_v4l2m2m,opus,pam,pbm,pcm_alaw,pcm_f32be,pcm_f32le,pcm_f64be,pcm_f64le,pcm_mulaw,pcm_s16be,pcm_s16be_planar,pcm_s16le,pcm_s16le_planar,pcm_s24be,pcm_s24le,pcm_s24le_planar,pcm_s32be,pcm_s32le,pcm_s32le_planar,pcm_s8,pcm_s8_planar,pcm_u16be,pcm_u16le,pcm_u24be,pcm_u24le,pcm_u32be,pcm_u32le,pcm_u8,pcx,pgm,pgmyuv,png,ppm,rawvideo,sgi,srt,ssa,sunrast,targa,text,tiff,v210,v308,v408,v410,vc1_qsv,vc1_v4l2m2m,vorbis,vp8_qsv,vp8_v4l2m2m,vp8_vaapi,vp9_qsv,vp9_vaapi,webvtt,wrapped_avframe,xbm,xwd,y41p,yuv4,zlib,' --enable-decoder=',libfdk_aac,ac3,ansi,apng,ass,av1_qsv,ayuv,bmp,dirac,exr,ffv1,ffvhuff,ffwavesynth,flac,gif,gsm,huffyuv,ilbc,jpeg2000,libaom,libaom_av1,libcodec2,libdav1d,libgsm,libilbc,libopenh264,libopenjpeg,libopus,libschroedinger,libspeex,libvorbis,libvpx_vp8,libvpx_vp9,mjpeg,mjpeg_qsv,mp1,mp1float,mp2,mp2float,mp3,mp3float,mpeg1video,mpeg1_v4l2m2m,mpeg2video,mpeg2_qsv,mpeg2_v4l2m2m,opus,pam,pbm,pcm_alaw,pcm_bluray,pcm_dvd,pcm_f32be,pcm_f32le,pcm_f64be,pcm_f64le,pcm_mulaw,pcm_s16be,pcm_s16be_planar,pcm_s16le,pcm_s16le_planar,pcm_s24be,pcm_s24le,pcm_s24le_planar,pcm_s32be,pcm_s32le,pcm_s32le_planar,pcm_s8,pcm_s8_planar,pcm_u16be,pcm_u16le,pcm_u24be,pcm_u24le,pcm_u32be,pcm_u32le,pcm_u8,pcx,pgm,pgmyuv,pgssub,pgx,png,ppm,rawvideo,sgi,srt,ssa,sunrast,targa,text,theora,tiff,v210,v210x,v308,v408,v410,vorbis,vp3,vp5,vp6,vp6a,vp6f,vp8,vp8_qsv,vp8_v4l2m2m,vp9,vp9_qsv,vp9_v4l2m2m,webp,webvtt,wrapped_avframe,xbm,xwd,y41p,yuv4,zlib,'
+ libavutil 57. 17.100 / 57. 17.100
+ libavcodec 59. 18.100 / 59. 18.100
+ libavformat 59. 16.100 / 59. 16.100
+ libavdevice 59. 4.100 / 59. 4.100
+ libavfilter 8. 24.100 / 8. 24.100
+ libswscale 6. 4.100 / 6. 4.100
+ libswresample 4. 3.100 / 4. 3.100
+ libpostproc 56. 3.100 / 56. 3.100
+Decoder libfdk_aac [Fraunhofer FDK AAC]:
+ General capabilities: dr1 chconf
+ Threading capabilities: none
+libfdk-aac decoder AVOptions:
+ -conceal <int> .D..A...... Error concealment method (from 0 to 2) (default noise)
+ spectral 0 .D..A...... Spectral muting
+ noise 1 .D..A...... Noise Substitution
+ energy 2 .D..A...... Energy Interpolation
+ -drc_boost <int> .D..A...... Dynamic Range Control: boost, where [0] is none and [127] is max boost (from -1 to 127) (default -1)
+ -drc_cut <int> .D..A...... Dynamic Range Control: attenuation factor, where [0] is none and [127] is max compression (from -1 to 127) (default -1)
+ -drc_level <int> .D..A...... Dynamic Range Control: reference level, quantized to 0.25dB steps where [0] is 0dB and [127] is -31.75dB, -1 for auto, and -2 for disabled (from -2 to 127) (default -1)
+ -drc_heavy <int> .D..A...... Dynamic Range Control: heavy compression, where [1] is on (RF mode) and [0] is off (from -1 to 1) (default -1)
+ -level_limit <boolean> .D..A...... Signal level limiting (default auto)
+ -drc_effect <int> .D..A...... Dynamic Range Control: effect type, where e.g. [0] is none and [6] is general (from -1 to 8) (default -1)
+
+```
+It does not indicate that it supports `fltp` decoding (and, indeed, it definitely does not support it). The decoder is [based on fixed-point arithmetic](https://wiki.hydrogenaud.io/index.php?title=Fraunhofer_FDK_AAC), and will [only accept 16-bit PCM input](https://wiki.hydrogenaud.io/index.php?title=Fraunhofer_FDK_AAC#Sample_Format) (presumably for encoding, not decoding, which is our focus), so this is not unexpected.
projects / thirdparty / shairport-sync.git / commitdiff
