[Fire General] hornpipe2:
I've been using my Fire 10 HD tablet to record videos of myself for a vlog. I use the front-facing camera and record segments approximately 15 minutes long. I've been doing this for a couple weeks. Usually, 10 minutes of video translates to a file of approximately 100MB.

Today I shot a video and, surprisingly, a 13 minute video consumed 1.14 GB of space - a ten-fold increase! I've changed nothing - there are no options in the Camera app for this device to adjust bitrate, resolution or fps of the front-facing camera. The only difference is that last night, my Fire tablet took an upgrade to the latest 5.6.2.0 Fire OS. I assume this has changed the system-wide bitrate for any camera capture, as the same change occurs using any other camera app from the Amazon store!

Here is some output from ffprobe. First, the video taken two days ago, showing a bitrate of 1402 kb/s:

C:\Users\grkenn\Desktop>ffmpeg-3.4.1-win64-shared\bin\ffprobe.exe VID_20180703_162653.mp4
ffprobe version 3.4.1 Copyright (c) 2007-2017 the FFmpeg developers
built with gcc 7.2.0 (GCC)
configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
libavutil 55. 78.100 / 55. 78.100
libavcodec 57.107.100 / 57.107.100
libavformat 57. 83.100 / 57. 83.100
libavdevice 57. 10.100 / 57. 10.100
libavfilter 6.107.100 / 6.107.100
libswscale 4. 8.100 / 4. 8.100
libswresample 2. 9.100 / 2. 9.100
libpostproc 54. 7.100 / 54. 7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'VID_20180703_162653.mp4':
Metadata:
major_brand : mp42
minor_version : 0
compatible_brands: isommp42
creation_time : 2018-07-03T21:26:53.000000Z
Duration: 00:12:38.52, start: 0.000000, bitrate: 1534 kb/s
Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 640x480, 1402 kb/s, SAR 1:1 DAR 4:3, 10.01 fps, 10 tbr, 90k tbn, 180k tbc (default)
Metadata:
creation_time : 2018-07-03T21:26:53.000000Z
handler_name : VideoHandle
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 128 kb/s (default)
Metadata:
creation_time : 2018-07-03T21:26:53.000000Z
handler_name : SoundHandle

And then the one for today, showing that the new recorded bitrate is 12298 kb/s:

C:\Users\grkenn\Desktop>ffmpeg-3.4.1-win64-shared\bin\ffprobe.exe VID_20180705_152646.mp4
ffprobe version 3.4.1 Copyright (c) 2007-2017 the FFmpeg developers
built with gcc 7.2.0 (GCC)
configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
libavutil 55. 78.100 / 55. 78.100
libavcodec 57.107.100 / 57.107.100
libavformat 57. 83.100 / 57. 83.100
libavdevice 57. 10.100 / 57. 10.100
libavfilter 6.107.100 / 6.107.100
libswscale 4. 8.100 / 4. 8.100
libswresample 2. 9.100 / 2. 9.100
libpostproc 54. 7.100 / 54. 7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'VID_20180705_152646.mp4':
Metadata:
major_brand : mp42
minor_version : 0
compatible_brands: isommp42
creation_time : 2018-07-05T20:26:46.000000Z
Duration: 00:13:14.93, start: 0.000000, bitrate: 12429 kb/s
Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 640x480, 12298 kb/s, SAR 1:1 DAR 4:3, 10.01 fps, 10.01 tbr, 90k tbn, 180k tbc (default)
Metadata:
creation_time : 2018-07-05T20:26:46.000000Z
handler_name : VideoHandle
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 128 kb/s (default)
Metadata:
creation_time : 2018-07-05T20:26:46.000000Z
handler_name : SoundHandle

I don't know of any way to control this quality setting, either through the Camera app itself or the device System Settings. Just wanted to put this information out there in case anyone else stumbles across the same problem or happens to find a fix for it.