Sur d’autres sites (8023)

• Why this shell command doesn't work ? ('command' works but 'command|cat' doesn't work)

  16 octobre 2018, par yabee

  Problem

  The following code outputs like...

  $ ffprobe -show_frames -select_streams v test.mp4 2>/dev/null|grep -A 2 key_frame=1
  
  key_frame=1
  
  pkt_pts=0
  
  pkt_pts_time=0:00:00.000000
  
  --
  
  key_frame=1
  
  pkt_pts=41041
  
  pkt_pts_time=0:00:01.710042
  
  --
  
  key_frame=1
  
  pkt_pts=64064
  
  pkt_pts_time=0:00:02.669333
  
  --
  
  key_frame=1
  
  pkt_pts=87087
  
  pkt_pts_time=0:00:03.628625
  
  --
  
  ...

  But the folowing one outputs nothing.

  $ ffprobe -show_frames -select_streams v test.mp4 2>/dev/null|grep -A 2 key_frame=1|cat

  And...

  $ ffprobe -show_frames -select_streams v test.mp4 2>/dev/null|grep key_frame=1
  
  key_frame=1
  
  key_frame=1
  
  key_frame=1
  
  key_frame=1
  
  $ ffprobe -show_frames -select_streams v test.mp4 2>/dev/null|grep key_frame=1|cat
  
  # Nothing outputted.

  Why ?

  Expected result

  What actually I want to do is

  $ ffprobe -show_frames -select_streams v test.mp4 2>/dev/null|grep -A 2key_frame=1|grep time
  
  pkt_pts_time=0:00:00.000000
  
  pkt_pts_time=0:00:01.710042
  
  pkt_pts_time=0:00:02.669333
  
  pkt_pts_time=0:00:03.628625
  
  ...

  But its result is

  $ ffprobe -show_frames -select_streams v test.mp4 2>/dev/null|grep -A 2key_frame=1|grep time
  
  # Nothing outputted.

  Grep works correctory exept it’s after ffprobe.

  $ seq 30|grep 1|grep 2
  
  12
  
  21

  Environment

  • Bash on Ubuntu on Windows 10 Pro
    • Windows version : 1803
    • Windows OS build : 17134.345

  Environment of Ubuntu :

  $ cat /etc/lsb-release
  
  DISTRIB_ID=Ubuntu
  
  DISTRIB_RELEASE=18.04
  
  DISTRIB_CODENAME=bionic
  
  DISTRIB_DESCRIPTION="Ubuntu 18.04.1 LTS"
  
  
  
  $ bash --version
  
  GNU bash, version 4.4.19(1)-release (x86_64-pc-linux-gnu)
  
  Copyright (C) 2016 Free Software Foundation, Inc.
  
  License GPLv3+: GNU GPL version 3 or later /gnu.org/licenses/gpl.html>
  
  
  
  This is free software; you are free to change and redistribute it.
  
  There is NO WARRANTY, to the extent permitted by law.
  
  
  
  $ ffprobe
  
  ffprobe version 3.4.4-0ubuntu0.18.04.1 Copyright (c) 2007-2018 the FFmpeg developers
  
    built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --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-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --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-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  
    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
  
    libavresample   3.  7.  0 /  3.  7.  0
  
    libswscale      4.  8.100 /  4.  8.100
  
    libswresample   2.  9.100 /  2.  9.100
  
    libpostproc    54.  7.100 / 54.  7.100
  
  Simple multimedia streams analyzer
  
  usage: ffprobe [OPTIONS] [INPUT_FILE]
  
  
  
  You have to specify one input file.
  
  Use -h to get full help or, even better, run 'man ffprobe'.

  What is problem ?

  Does grep or ffprobe change its behavior by existence of pipe in this case ?
  Thanks.

• Dramatic loss in quality while streaming video with FFMPEG and filter_complex

  17 juin 2022, par Holocene121

  I'm trying to overlay an image while I stream a .MP4 video to RTMP.

  


  It's currently working with the following command, however, there is a dramatic difference in quality. It is now pixelated and fuzzy.

  


  ffmpeg -re -i "video.mp4" -i "image.png" -filter_complex overlay -c:a copy -f flv rtmp://localhost/live/stream


  


  Is there a way to maintain close to the original quality while still overlaying an image ?

  


• How convert video file from vp8 to h264 in java ?

  25 mai 2018, par tostao

  I can do it via command line :

  ffmpeg -fflags +genpts -i in.mp4 -r 24 out.mp4

  but I am not able to do it in java. I tried to do this via javacv :

  FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(bis);
  
              grabber.setOption("fflags", "genpts");
  
              grabber.start();
  
              ByteArrayOutputStream out = new ByteArrayOutputStream();
  
              FFmpegFrameRecorder2 recorder = new FFmpegFrameRecorder2(out, grabber.getImageWidth(), grabber.getImageHeight(), grabber.getAudioChannels());
  
              recorder.setVideoCodecName("h264");
  
              recorder.setAudioCodecName("aac");
  
              recorder.setFormat("mp4");
  
              recorder.setFrameRate(grabber.getFrameRate());
  
  //          recorder.setOption("-fflags +genpts -i", " ");
  
  //          recorder.setOption("movflags" ,"frag_keyframe+genpts");
  
              recorder.setOption("r", "23");
  
              recorder.setSampleRate(grabber.getSampleRate());
  
              recorder.start();
  
              Frame frame;
  
              while ((frame = grabber.grabFrame()) != null) {
  
                  recorder.record(frame);
  
              }
  
              recorder.stop();
  
              grabber.stop();

  But can not add parameters from command line above. I tried jcodec but looks like wp8 is not supportet.

  Any advice, tip how can I do it ?