$ mencoder tv:// -tv driver=v4l2:device=/dev/video0:norm=SECAM:alsa:adevice=hw.2:forceaudio:volume=80:immediatemode=0 -oac lavc -lavcopts acodec=libmp3lame:abitrate=192 -srate 48000 -ovc x264 -x264encopts global_header:nr=200:threads=auto:frameref=4:subq=4:8x8dct:crf=25:trellis=1:keyint=1000:keyint_min=10:bframes=16:b-adapt=1:b_pyramid=normal -of lavf -lavfopts format=mp4 -noskip -o output1.mp4

MEncoder 1.4-9.mga8.tainted-10 (C) 2000-2019 MPlayer Team
success: format: 9  data: 0x0 - 0x0
TV file format detected.
Selected driver: v4l2
 name: Video 4 Linux 2 input
 author: Martin Olschewski <olschewski@zpr.uni-koeln.de>
 comment: first try, more to come ;-)
Selected device: Geniatech OTG102
 Capabilities:  video capture  VBI capture device  read/write  streaming
 supported norms: 0 = NTSC; 1 = NTSC-M; 2 = NTSC-M-JP; 3 = NTSC-M-KR; 4 = NTSC-443; 5 = PAL; 6 = PAL-BG; 7 = PAL-H; 8 = PAL-I; 9 = PAL-DK; 10 = PAL-M; 11 = PAL-N; 12 = PAL-Nc; 13 = PAL-60; 14 = SECAM; 15 = SECAM-B; 16 = SECAM-G; 17 = SECAM-H; 18 = SECAM-DK; 19 = SECAM-L; 20 = SECAM-Lc;
 inputs: 0 = Composite1; 1 = S-Video;
 Current input: 0
 Current format: YUYV
v4l2: ioctl set format failed: Invalid argument
v4l2: ioctl set format failed: Invalid argument
v4l2: ioctl set format failed: Invalid argument
Selected input hasn't got a tuner!
[V] filefmt:9  fourcc:0x32595559  size:640x480  fps:25.000  ftime:=0.0400
==========================================================================
Opening audio decoder: [pcm] Uncompressed PCM audio decoder
AUDIO: 48000 Hz, 2 ch, s16le, 1536.0 kbit/100.00% (ratio: 192000->192000)
Selected audio codec: [pcm] afm: pcm (Uncompressed PCM)
==========================================================================
libavformat version 58.45.100 (external)
Mismatching header version 58.20.100
** MUXER_LAVF *****************************************************************
REMEMBER: MEncoder's libavformat muxing is presently broken and can generate
INCORRECT files in the presence of B-frames. Moreover, due to bugs MPlayer
will play these INCORRECT files as if nothing were wrong!
*******************************************************************************
OK, exit.
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
==========================================================================
Opening video decoder: [raw] RAW Uncompressed Video
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
Movie-Aspect is undefined - no prescaling applied.
[swscaler @ 0x7f8b7e602120]bicubic scaler, from yuyv422 to yuv420p using MMXEXT
[swscaler @ 0x7f8b7e602120]using unscaled yuyv422 -> yuv420p special converter
x264 [info]: using SAR=1/1
x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
x264 [info]: profile High, level 3.0, 4:2:0, 8-bit
Selected video codec: [rawyuy2] vfm: raw (RAW YUY2)
==========================================================================
libavcodec version 58.91.100 (external)
Mismatching header version 58.35.100
[libmp3lame @ 0x7f8b7dadc960]Channel layout not specified
Forcing audio preload to 0, max pts correction to 0.
Erreur de segmentation (core dumped)rem:   0min   0mb  A-V:0.000 [0:0]


mencoder seems to be compiled with wrong version header.
Interesting part:
libavformat version 58.45.100 (external)
Mismatching header version 58.20.100

libavcodec version 58.91.100 (external)
Mismatching header version 58.35.100
[libmp3lame @ 0x7f8b7dadc960]Channel layout not specified
Forcing audio preload to 0, max pts correction to 0.
Erreur de segmentation (core dumped)rem:   0min   0mb  A-V:0.000 [0:0]

In system journal:
kernel: traps: mencoder[10415] general protection fault ip:7f8b7cb45753 sp:7ffe23eb7d30 error:0 in libavutil.so.56.51.100[7f8b7cb3a000+6c000]