Loss of data when input is Unix Domain Socket

[ku7iex2E]

Failed when via unix socket, but nothing wrong when you input it just as a normal file.
The mp4 file could be found in attatchment.
log of unix socket one:

% cat 1.mp4 | socat - unix-listen:/tmp/abcd &
% ffmpeg -report  -i unix:///tmp/abcd -c copy out.mkv

ffmpeg started on 2021-07-24 at 23:10:04
Report written to "ffmpeg-20210724-231004.log"
Log level: 48
Command line:
ffmpeg -report -i unix:///tmp/abcd -c copy out.mkv
ffmpeg version n4.4 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 11.1.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-shared --enable-version3
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
Splitting the commandline.
Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
Reading option '-i' ... matched as input url with argument 'unix:///tmp/abcd'.
Reading option '-c' ... matched as option 'c' (codec name) with argument 'copy'.
Reading option 'out.mkv' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option report (generate a report) with argument 1.
Successfully parsed a group of options.
Parsing a group of options: input url unix:///tmp/abcd.
Successfully parsed a group of options.
Opening an input file: unix:///tmp/abcd.
[NULL @ 0x55b6bf062440] Opening 'unix:///tmp/abcd' for reading
[unix @ 0x55b6bf0630c0] No default whitelist set
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] Format mov,mp4,m4a,3gp,3g2,mj2 probed with size=2048 and score=100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] ISO: File Type Major Brand: dash
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] Unknown dref type 0x206c7275 size 12
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180002970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180004500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180006030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180007470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180009000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180010530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180011970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180013500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180015030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180016470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180018000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180019530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180020970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180022500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180024030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180025470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180027000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180028530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180029970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180031500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180033030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180034470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180036000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180037530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180038970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180040500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180042030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180043470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180045000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180046530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180047970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180049500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180051030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180052470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180054000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180055530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180056970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180058500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180060030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180061470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180063000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180064530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180065970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180067500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180069030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180070470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180072000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180073530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180074970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180076500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180078030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180079470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180081000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180082530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180083970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180085500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180087030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180088470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180090000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] found tfdt time 180091530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] Before avformat_find_stream_info() pos: 543003 bytes read:543003 seeks:0 nb_streams:1
[h264 @ 0x55b6bf064480] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x55b6bf064480] nal_unit_type: 8(PPS), nal_ref_idc: 3
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] stream 0, offset 0x885: partial file
[h264 @ 0x55b6bf064480] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x55b6bf064480] nal_unit_type: 8(PPS), nal_ref_idc: 3
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), none, 1920x1080, 2 kb/s): unspecified pixel format
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] After avformat_find_stream_info() pos: 543003 bytes read:543003 seeks:0 frames:0
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'unix:///tmp/abcd':
  Metadata:
    major_brand     : dash
    minor_version   : 0
    compatible_brands: iso6avc1mp41
    creation_time   : 2021-07-23T10:29:14.000000Z
  Duration: 00:33:21.03, bitrate: N/A
  Stream #0:0(und), 0, 1/90000: Video: h264 (avc1 / 0x31637661), none, 1920x1080, 2 kb/s, 60 fps, 90k tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2021-07-23T10:29:14.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 07/23/2021.
      vendor_id       : [0][0][0][0]
Successfully opened the file.
Parsing a group of options: output url out.mkv.
Applying option c (codec name) with argument copy.
Successfully parsed a group of options.
Opening an output file: out.mkv.
[file @ 0x55b6bf06a380] Setting default whitelist 'file,crypto,data'
Successfully opened the file.
[matroska @ 0x55b6bf08fec0] get_metadata_duration returned: 0
Output #0, matroska, to 'out.mkv':
  Metadata:
    major_brand     : dash
    minor_version   : 0
    compatible_brands: iso6avc1mp41
    encoder         : Lavf58.76.100
  Stream #0:0(und), 0, 1/1000: Video: h264 (avc1 / 0x31637661), none, 1920x1080, q=2-31, 2 kb/s, 60 fps, 90k tbr, 1k tbn, 90k tbc (default)
    Metadata:
      creation_time   : 2021-07-23T10:29:14.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 07/23/2021.
      vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
cur_dts is invalid st:0 (0) [init:1 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x55b6bf062440] stream 0, offset 0x3aa3c: partial file
unix:///tmp/abcd: Invalid data found when processing input
frame=    0 fps=0.0 q=-1.0 size=       1kB time=00:00:00.00 bitrate=N/A speed=N/A    
No more output streams to write to, finishing.
[matroska @ 0x55b6bf08fec0] end duration = 0
[matroska @ 0x55b6bf08fec0] stream 0 end duration = 0
frame=    0 fps=0.0 q=-1.0 Lsize=       1kB time=00:00:00.00 bitrate=N/A speed=   0x    
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Input file #0 (unix:///tmp/abcd):
  Input stream #0:0 (video): 0 packets read (0 bytes); 
  Total: 0 packets (0 bytes) demuxed
Output file #0 (out.mkv):
  Output stream #0:0 (video): 0 packets muxed (0 bytes); 
  Total: 0 packets (0 bytes) muxed
0 frames successfully decoded, 0 decoding errors
[AVIOContext @ 0x55b6bf06a5c0] Statistics: 0 seeks, 1 writeouts
[AVIOContext @ 0x55b6bf06b4c0] Statistics: 543003 bytes read, 0 seeks

as normal file:

% ffmpeg -report -i 1.mp4 -c copy out.mkv

ffmpeg started on 2021-07-24 at 23:18:12
Report written to "ffmpeg-20210724-231812.log"
Log level: 48
Command line:
ffmpeg -report -i 1.mp4 -c copy out.mkv
ffmpeg version n4.4 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 11.1.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-shared --enable-version3
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
Splitting the commandline.
Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
Reading option '-i' ... matched as input url with argument '1.mp4'.
Reading option '-c' ... matched as option 'c' (codec name) with argument 'copy'.
Reading option 'out.mkv' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option report (generate a report) with argument 1.
Successfully parsed a group of options.
Parsing a group of options: input url 1.mp4.
Successfully parsed a group of options.
Opening an input file: 1.mp4.
[NULL @ 0x562e0207f440] Opening '1.mp4' for reading
[file @ 0x562e020800c0] Setting default whitelist 'file,crypto,data'
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] Format mov,mp4,m4a,3gp,3g2,mj2 probed with size=2048 and score=100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] ISO: File Type Major Brand: dash
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] Unknown dref type 0x206c7275 size 12
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180002970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180004500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180006030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180007470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180009000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180010530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180011970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180013500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180015030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180016470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180018000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180019530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180020970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180022500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180024030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180025470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180027000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180028530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180029970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180031500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180033030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180034470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180036000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180037530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180038970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180040500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180042030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180043470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180045000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180046530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180047970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180049500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180051030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180052470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180054000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180055530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180056970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180058500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180060030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180061470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180063000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180064530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180065970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180067500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180069030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180070470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180072000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180073530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180074970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180076500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180078030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180079470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180081000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180082530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180083970, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180085500, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180087030, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180088470, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180090000, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] found tfdt time 180091530, using it for dts
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] Before avformat_find_stream_info() pos: 538788 bytes read:335691 seeks:1 nb_streams:1
[h264 @ 0x562e02081440] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x562e02081440] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 0x562e02081440] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x562e02081440] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 0x562e02081440] nal_unit_type: 5(IDR), nal_ref_idc: 1
[h264 @ 0x562e02081440] Format yuv420p chosen by get_format().
[h264 @ 0x562e02081440] Reinit context to 1920x1088, pix_fmt: yuv420p
[h264 @ 0x562e02081440] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 1
[h264 @ 0x562e02081440] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 1
[h264 @ 0x562e02081440] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 1
[h264 @ 0x562e02081440] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 1
[h264 @ 0x562e02081440] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 1
[h264 @ 0x562e02081440] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 1
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] All info found
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] rfps: 59.000000 0.009372
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] rfps: 59.000000 0.009372
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] rfps: 60.000000 0.000259
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] rfps: 120.000000 0.001036
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] rfps: 240.000000 0.004144
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] rfps: 59.940060 0.000285
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] rfps: 59.940060 0.000285
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562e0207f440] After avformat_find_stream_info() pos: 325855 bytes read:671894 seeks:2 frames:21
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.mp4':
  Metadata:
    major_brand     : dash
    minor_version   : 0
    compatible_brands: iso6avc1mp41
    creation_time   : 2021-07-23T10:29:14.000000Z
  Duration: 00:33:21.03, start: 2000.033000, bitrate: 2 kb/s
  Stream #0:0(und), 21, 1/90000: Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 2 kb/s, 60 fps, 60 tbr, 90k tbn, 120 tbc (default)
    Metadata:
      creation_time   : 2021-07-23T10:29:14.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 07/23/2021.
      vendor_id       : [0][0][0][0]
Successfully opened the file.
Parsing a group of options: output url out.mkv.
Applying option c (codec name) with argument copy.
Successfully parsed a group of options.
Opening an output file: out.mkv.
[file @ 0x562e021a7b40] Setting default whitelist 'file,crypto,data'
Successfully opened the file.
[matroska @ 0x562e020a9140] get_metadata_duration returned: 0
Output #0, matroska, to 'out.mkv':
  Metadata:
    major_brand     : dash
    minor_version   : 0
    compatible_brands: iso6avc1mp41
    encoder         : Lavf58.76.100
  Stream #0:0(und), 0, 1/1000: Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 2 kb/s, 60 fps, 60 tbr, 1k tbn, 90k tbc (default)
    Metadata:
      creation_time   : 2021-07-23T10:29:14.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 07/23/2021.
      vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
cur_dts is invalid st:0 (0) [init:1 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
[matroska @ 0x562e020a9140] Starting new cluster with timestamp 0 at offset 813 bytes
[matroska @ 0x562e020a9140] Writing block of size 237899 with pts 0, dts 0, duration 17 at relative offset 9 in cluster at offset 813. TrackNumber 1, keyframe 1
frame=    1 fps=0.0 q=-1.0 size=       1kB time=00:00:00.00 bitrate=6504.0kbits/s speed=N/A    
[matroska @ 0x562e020a9140] Writing block of size 3299 with pts 17, dts 17, duration 17 at relative offset 237916 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 3590 with pts 34, dts 34, duration 17 at relative offset 241222 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5085 with pts 50, dts 50, duration 17 at relative offset 244819 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5473 with pts 67, dts 67, duration 17 at relative offset 249911 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 450 with pts 84, dts 84, duration 17 at relative offset 255391 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5351 with pts 100, dts 100, duration 17 at relative offset 255848 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 2725 with pts 117, dts 117, duration 17 at relative offset 261206 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5392 with pts 134, dts 134, duration 17 at relative offset 263938 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4868 with pts 150, dts 150, duration 17 at relative offset 269337 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6532 with pts 167, dts 167, duration 17 at relative offset 274212 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5220 with pts 184, dts 184, duration 17 at relative offset 280751 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4625 with pts 200, dts 200, duration 17 at relative offset 285978 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6163 with pts 217, dts 217, duration 17 at relative offset 290610 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4404 with pts 234, dts 234, duration 17 at relative offset 296780 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 2283 with pts 250, dts 250, duration 17 at relative offset 301191 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5051 with pts 267, dts 267, duration 17 at relative offset 303481 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 2612 with pts 284, dts 284, duration 17 at relative offset 308539 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4273 with pts 300, dts 300, duration 17 at relative offset 311158 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5313 with pts 317, dts 317, duration 17 at relative offset 315438 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 906 with pts 334, dts 334, duration 17 at relative offset 320758 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5078 with pts 350, dts 350, duration 17 at relative offset 321671 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6375 with pts 367, dts 367, duration 17 at relative offset 326756 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4300 with pts 384, dts 384, duration 17 at relative offset 333138 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5380 with pts 400, dts 400, duration 17 at relative offset 337445 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5098 with pts 417, dts 417, duration 17 at relative offset 342832 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6783 with pts 434, dts 434, duration 17 at relative offset 347937 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 10311 with pts 450, dts 450, duration 17 at relative offset 354727 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 8328 with pts 467, dts 467, duration 17 at relative offset 365045 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6470 with pts 484, dts 484, duration 17 at relative offset 373380 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5430 with pts 500, dts 500, duration 17 at relative offset 379857 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5271 with pts 517, dts 517, duration 17 at relative offset 385294 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4991 with pts 534, dts 534, duration 17 at relative offset 390572 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6380 with pts 550, dts 550, duration 17 at relative offset 395570 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5495 with pts 567, dts 567, duration 17 at relative offset 401957 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4340 with pts 584, dts 584, duration 17 at relative offset 407459 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5432 with pts 600, dts 600, duration 17 at relative offset 411806 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5549 with pts 617, dts 617, duration 17 at relative offset 417245 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4001 with pts 634, dts 634, duration 17 at relative offset 422801 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 3842 with pts 650, dts 650, duration 17 at relative offset 426809 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 3661 with pts 667, dts 667, duration 17 at relative offset 430658 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5283 with pts 684, dts 684, duration 17 at relative offset 434326 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5755 with pts 700, dts 700, duration 17 at relative offset 439616 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5392 with pts 717, dts 717, duration 17 at relative offset 445378 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 3386 with pts 734, dts 734, duration 17 at relative offset 450777 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6487 with pts 750, dts 750, duration 17 at relative offset 454170 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6699 with pts 767, dts 767, duration 17 at relative offset 460664 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5304 with pts 784, dts 784, duration 17 at relative offset 467370 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6309 with pts 800, dts 800, duration 17 at relative offset 472681 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6159 with pts 817, dts 817, duration 17 at relative offset 478997 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4314 with pts 834, dts 834, duration 17 at relative offset 485163 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4979 with pts 850, dts 850, duration 17 at relative offset 489484 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5891 with pts 867, dts 867, duration 17 at relative offset 494470 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4320 with pts 884, dts 884, duration 17 at relative offset 500368 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 6222 with pts 900, dts 900, duration 17 at relative offset 504695 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 3915 with pts 917, dts 917, duration 17 at relative offset 510924 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5739 with pts 934, dts 934, duration 17 at relative offset 514846 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 5626 with pts 950, dts 950, duration 17 at relative offset 520592 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4426 with pts 967, dts 967, duration 17 at relative offset 526225 in cluster at offset 813. TrackNumber 1, keyframe 0
[matroska @ 0x562e020a9140] Writing block of size 4215 with pts 984, dts 984, duration 17 at relative offset 530658 in cluster at offset 813. TrackNumber 1, keyframe 0
No more output streams to write to, finishing.
[matroska @ 0x562e020a9140] end duration = 1001
[matroska @ 0x562e020a9140] stream 0 end duration = 1001
frame=   60 fps=0.0 q=-1.0 Lsize=     523kB time=00:00:00.98 bitrate=4351.1kbits/s speed= 437x    
video:522kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.239124%
Input file #0 (1.mp4):
  Input stream #0:0 (video): 60 packets read (534450 bytes); 
  Total: 60 packets (534450 bytes) demuxed
Output file #0 (out.mkv):
  Output stream #0:0 (video): 60 packets muxed (534450 bytes); 
  Total: 60 packets (534450 bytes) muxed
0 frames successfully decoded, 0 decoding errors
[AVIOContext @ 0x562e021aba40] Statistics: 2 seeks, 4 writeouts
[AVIOContext @ 0x562e02088480] Statistics: 876513 bytes read, 2 seeks

[dank074]

I have also encountered this bug using Ffmpeg version 6.1.1-3ubuntu5

It seems that there is loss of data when using a Unix Domain Socket as input. A chunk of initial bytes are lost.

I created sample script to reproduce the bug here: ​https://github.com/dank074/ffmpeg-unix-socket-bug

In my sample code I generated two outputs: one using the sample file as input directly, and the other using a Unix Domain Socket as input which contains the same file. The resulting output from the Unix Domain Socket input is missing 65536 bytes of data when compared to the same ffmpeg command that uses the original file as input.