Recherche avancée

Sur d’autres sites (7127)

• Not reading the first character of every second line in a file [duplicate]

  13 janvier 2024, par Monki Majik

  In a BASH script (latest Xubuntu) this successfully reads and prints every line in mp4.txt

  


  ls *.mp4 > mp4.txt
while read F ; do
    echo $F
    echo ${F/mp4}mkv
#        ffmpeg -i "$F" -map 0 -c copy "${F/mp4}mkv"
done < ./mp4.txt


  


  Uncommenting the ffmpeg line causes the first character from every other line in mp4.txt to not be in F.

  


  I'm expecting every file line to be read consistently.

  


  I've tried Bash : Special characters lost when reading file

  


• Using ffmpeg to rotate videos through metadata

  14 octobre 2015, par Gary Dale

  I am using Debian/Stretch AMD64. I have some videos that I need to rotate either 90 or 180 degrees. I’ve read the multiple answers for this that suggest using

  ffmpeg -i input.mp4 -c copy -metadata:s:v:0 rotate=-90 output.mp4
  
  ffprobe -v quiet output.mp4 -show_streams|grep rot

  with the second command verifying the first one worked.

  The problem I’m having is that I can’t get the video to actually rotate properly. Moreover I’m getting different video depending on whether I play with VLC or KMlayer.

  The original video needs to be rotated 90 degrees clockwise. However VLC and KMPlayer play it rotated 90 degrees counterclockwise when I use a rotation of -90. ffprobe shows no match for "rot".

  When I specify a rotation of 90, VLC plays the rotated output like the input while KMPlayer again shows it rotated counterclockwise - the same as for the -90 rotation. This time ffprobe shows TAG:rotate=90 and rotation=-90.

  When I specify a rotation of 270 degrees, again VLC shows no change from the original input while KMPlayer shows the same as the 90 degree rotation.ffprobe shows TAG:rotate=270 and rotation=90

  Finally when I rotate the video -270, I get the same results as 270 except the tags disappear from ffprobe.

  Clearly both VLC and KMPlayer are trying to use the metadata but neither interpreting the same way nor applying it correctly.

  I’m not sure why I’m getting different results from VLC after rotating -90 and 270 when the rot tags are missing in both cases. Nor do I understand why KMPLayer consistently shows the video rotated 90 degrees counterclockwise after any change in the meta information rotation tags.

  Because there are two metatags dealing with rotation (rotate and rotation), I suspect that there is an interaction between them that I need to address with the ffmpeg command line. However I can’t find the information in the man pages.

  Any ideas ?

  Full console output :

      ffmpeg version 2.8-1 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 5.2.1 (Debian 5.2.1-17) 20150911
  
    configuration: --prefix=/usr --extra-version=1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-openal --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-opengl --enable-x11grab --enable-libiec61883 --enable-libdc1394 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  
    libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '20150725_192326.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2015-07-25 23:28:25
  
    Duration: 00:04:56.55, start: 0.000000, bitrate: 17245 kb/s
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 16999 kb/s, 30.01 fps, 30 tbr, 90k tbn, 180k tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2015-07-25 23:28:25
  
        handler_name    : VideoHandle
  
      Side data:
  
        displaymatrix: rotation of -90.00 degrees
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 256 kb/s (default)
  
      Metadata:
  
        creation_time   : 2015-07-25 23:28:25
  
        handler_name    : SoundHandle
  
  File '20150725_192326-rotated.mp4' already exists. Overwrite ? [y/N] y
  
  [mp4 @ 0x1749fc0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x1749fc0] Codec for stream 1 does not use global headers but container format requires global headers
  
  Output #0, mp4, to '20150725_192326-rotated.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      encoder         : Lavf56.40.101
  
      Stream #0:0(eng): Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1920x1080, q=2-31, 16999 kb/s, 30.01 fps, 30 tbr, 90k tbn, 90k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandle
  
        creation_time   : 2015-07-25 23:28:25
  
        rotate          : -90
  
      Stream #0:1(eng): Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 256 kb/s (default)
  
      Metadata:
  
        creation_time   : 2015-07-25 23:28:25
  
        handler_name    : SoundHandle
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  frame= 8891 fps=3137 q=-1.0 Lsize=  624465kB time=00:04:56.55 bitrate=17250.0kbits/s    
  
  video:614880kB audio:9267kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.050998%

• Raspberry Pi and FFMpeg live streaming video to backend Node.js server, but how do I deliver it to the front end ?

  2 août 2023, par qwet142

  I'm attempting this setup to live stream video from a Raspberry Pi to a publicly available website, and from the backend server using Node.js and Express, I would like to serve it to the front end with minimal latency available to many viewers (will be hosted somewhere like Netlify to handle distribution).

  


  WebRTC is too complex for my use case and timeframe. HLC appears to have too high a latency as I need <4s consistently. I would like to something compatible with Node.js. I am a beginner in this domain, familiar only with general programming and web development.

  &#xA;