% ffmpeg -i first.avi -s 320x240 -vcodec libx264 -acodec aac -strict experimental -ac 2 -r 15 -ab 44100 -aspect 16:9 first.mp4
ffmpeg version 3.2.12-1~deb9u1 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --prefix=/usr --extra-version='1~deb9u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libebur128 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 34.101 / 55. 34.101
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.101 / 57. 56.101
  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
Guessed Channel Layout for Input Stream #0.1 : mono
Input #0, avi, from 'first.avi':
  Metadata:
    maker           : NIKON CORPORATION
    model           : NIKON D90
    creation_time   : 2019-05-15 00:01:06
  Duration: 00:01:16.00, start: 0.000000, bitrate: 20683 kb/s
    Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, 20511 kb/s, 24 fps, 24 tbr, 24 tbn, 24 tbc
    Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 11025 Hz, mono, s16, 176 kb/s
[swscaler @ 0x564c431775a0] deprecated pixel format used, make sure you did set range correctly
No pixel format specified, yuvj422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[libx264 @ 0x564c4313cd40] using SAR=4/3
[libx264 @ 0x564c4313cd40] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x564c4313cd40] profile High 4:2:2, level 1.2, 4:2:2 8-bit
[libx264 @ 0x564c4313cd40] 264 - core 148 r2748 97eaef2 - H.264/MPEG-4 AVC codec - Copyleft 2003-2016 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=15 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'first.mp4':
  Metadata:
    maker           : NIKON CORPORATION
    model           : NIKON D90
    encoder         : Lavf57.56.101
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuvj422p(pc), 320x240 [SAR 4:3 DAR 16:9], q=-1--1, 15 fps, 15360 tbn, 15 tbc
    Metadata:
      encoder         : Lavc57.64.101 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
    Stream #0:1: Audio: aac (LC) ([64][0][0][0] / 0x0040), 11025 Hz, stereo, fltp, 44 kb/s
    Metadata:
      encoder         : Lavc57.64.101 aac
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
Past duration 0.750008 too large
frame= 1142 fps= 75 q=-1.0 Lsize=    3538kB time=00:01:16.06 bitrate= 381.0kbits/s dup=0 drop=682 speed=4.97x
video:3095kB audio:411kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.903609%
[libx264 @ 0x564c4313cd40] frame I:7     Avg QP:21.63  size: 15388
[libx264 @ 0x564c4313cd40] frame P:319   Avg QP:23.58  size:  6317
[libx264 @ 0x564c4313cd40] frame B:816   Avg QP:28.34  size:  1282
[libx264 @ 0x564c4313cd40] consecutive B-frames:  2.7%  4.7%  3.9% 88.6%
[libx264 @ 0x564c4313cd40] mb I  I16..4:  1.3% 56.3% 42.4%
[libx264 @ 0x564c4313cd40] mb P  I16..4:  0.2%  4.0%  2.3%  P16..4: 33.8% 32.1% 25.4%  0.0%  0.0%    skip: 2.3%
[libx264 @ 0x564c4313cd40] mb B  I16..4:  0.0%  0.3%  0.2%  B16..8: 43.6% 12.4%  4.2%  direct: 6.4%  skip:32.8%  L0:38.5% L1:42.9% BI:18.6%
[libx264 @ 0x564c4313cd40] 8x8 transform intra:59.6% inter:54.4%
[libx264 @ 0x564c4313cd40] coded y,uvDC,uvAC intra: 91.3% 87.0% 62.6% inter: 32.3% 32.2% 8.4%
[libx264 @ 0x564c4313cd40] i16 v,h,dc,p: 35% 24%  8% 33%
[libx264 @ 0x564c4313cd40] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 23% 21% 11%  6%  5%  7%  8%  6% 11%
[libx264 @ 0x564c4313cd40] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 28% 15% 13%  6%  7% 10%  8%  6%  8%
[libx264 @ 0x564c4313cd40] i8c dc,h,v,p: 56% 15% 22%  7%
[libx264 @ 0x564c4313cd40] Weighted P-Frames: Y:12.9% UV:8.2%
[libx264 @ 0x564c4313cd40] ref P L0: 52.2% 21.5% 14.1% 11.0%  1.2%
[libx264 @ 0x564c4313cd40] ref B L0: 85.1% 11.6%  3.4%
[libx264 @ 0x564c4313cd40] ref B L1: 93.8%  6.2%
[libx264 @ 0x564c4313cd40] kb/s:332.96
[aac @ 0x564c43153200] Qavg: 1552.912