Kdenlive 16.08.1
Fedora 24
MLT 6.2.0

When I edit an MP4 file, there isn't any audio:

ffprobe ExtraLife\ Contraption\ Maker\ Ep\ 08\ -\ Final\ 2016\ Contraptions.mp4
ffprobe version 3.2.2 Copyright (c) 2007-2016 the FFmpeg developers
built with gcc 6.3.1 (GCC) 20161221 (Red Hat 6.3.1-1)
configuration: --arch=x86_64 --bindir=/usr/bin --datadir=/usr/share/ffmpeg --disable-debug --disable-static --disable-stripping --enable-avfilter --enable-avresample --enable-bzlib --enable-cuda --enable-cuvid --enable-libnpp --enable-doc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gpl --enable-iconv --enable-libass --enable-libbluray --enable-libcdio --enable-libdc1394 --enable-libebur128 --enable-libfdk-aac --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libkvazaar --enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libv4l2 --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxcb-shm --enable-libxcb-xfixes --enable-libxcb-shape --enable-libxvid --enable-libzvbi --enable-lzma --enable-nonfree --enable-openal --enable-opencl --enable-nvenc --enable-opengl --enable-postproc --enable-pthreads --enable-sdl2 --enable-shared --enable-version3 --enable-x11grab --enable-xlib --enable-zlib --extra-cflags='-I/usr/include/nvenc -I/usr/include/cuda' --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic' --prefix=/usr --shlibdir=/usr/lib64 --enable-runtime-cpudetect
libavutil 55. 34.100 / 55. 34.100
libavcodec 57. 64.101 / 57. 64.101
libavformat 57. 56.100 / 57. 56.100
libavdevice 57. 1.100 / 57. 1.100
libavfilter 6. 65.100 / 6. 65.100
libavresample 3. 1. 0 / 3. 1. 0
libswscale 4. 2.100 / 4. 2.100
libswresample 2. 3.100 / 2. 3.100
libpostproc 54. 1.100 / 54. 1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'ExtraLife Contraption Maker Ep 08 - Final 2016 Contraptions.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf57.56.100
Duration: 00:22:02.43, start: 0.000000, bitrate: 631 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/unknown/bt709), 1920x1080 [SAR 1:1 DAR 16:9], 628 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
Metadata:
handler_name : VideoHandler

when I render WebM file, there is audio:

ffprobe ExtraLife\ Contraption\ Maker\ Ep\ 08\ -\ Final\ 2016\ Contraptions.webm
ffprobe version 3.2.2 Copyright (c) 2007-2016 the FFmpeg developers
built with gcc 6.3.1 (GCC) 20161221 (Red Hat 6.3.1-1)
configuration: --arch=x86_64 --bindir=/usr/bin --datadir=/usr/share/ffmpeg --disable-debug --disable-static --disable-stripping --enable-avfilter --enable-avresample --enable-bzlib --enable-cuda --enable-cuvid --enable-libnpp --enable-doc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gpl --enable-iconv --enable-libass --enable-libbluray --enable-libcdio --enable-libdc1394 --enable-libebur128 --enable-libfdk-aac --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libkvazaar --enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libv4l2 --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxcb-shm --enable-libxcb-xfixes --enable-libxcb-shape --enable-libxvid --enable-libzvbi --enable-lzma --enable-nonfree --enable-openal --enable-opencl --enable-nvenc --enable-opengl --enable-postproc --enable-pthreads --enable-sdl2 --enable-shared --enable-version3 --enable-x11grab --enable-xlib --enable-zlib --extra-cflags='-I/usr/include/nvenc -I/usr/include/cuda' --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic' --prefix=/usr --shlibdir=/usr/lib64 --enable-runtime-cpudetect
libavutil 55. 34.100 / 55. 34.100
libavcodec 57. 64.101 / 57. 64.101
libavformat 57. 56.100 / 57. 56.100
libavdevice 57. 1.100 / 57. 1.100
libavfilter 6. 65.100 / 6. 65.100
libavresample 3. 1. 0 / 3. 1. 0
libswscale 4. 2.100 / 4. 2.100
libswresample 2. 3.100 / 2. 3.100
libpostproc 54. 1.100 / 54. 1.100
[matroska,webm @ 0xaa37c0] Duplicate element
Input #0, matroska,webm, from 'ExtraLife Contraption Maker Ep 08 - Final 2016 Contraptions.webm':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: vp8, yuv420p, 1920x1080, SAR 1:1 DAR 16:9, 1k fps, 30 tbr, 1k tbn, 1k tbc (default)
Stream #0:1: Audio: vorbis, 48000 Hz, stereo, fltp (default)

The source is MP4 (H264) with AAC audio and I can play it in the Monitor window. So the system is capable of decoding H264 and AAC.

Ideas? Questions? More info needed?

Thanks!

Some extra info that might be useful:

$ rpm -aq *faac*
faac-1.28-7.fc24.x86_64

$ rpm -aq *faad*
faad2-libs-2.7-8.fc24.x86_64