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• How to extract key-frames closest to given frame numbers from H264 video with ffmpeg

  16 décembre 2016, par John Allard

  I know how to extract a set of frames as jpg files from a video using ffmpeg if you know the frame numbers (given below)

  Extracting Frames: [40, 59, 73, 110]
  
  /usr/bin/ffmpeg -y -hide_banner -nostats -loglevel error -i /home/pi/movie.mp4 -vf select='eq(n\,40)+eq(n\,59)+eq(n\,73)+eq(n\,110)',scale=640:-1 -vsync 0 /tmp/%04d.jpg

  That will extract frames [40, 59, 73, 110] as files /tmp/0000.jpg, /tmp/0001.jpg, etc.

  I also know how to extract all key frames for a given time interval :

  ffmpeg -ss  -i video.mp4 -t <duration> -q:v 2 -vf select="eq(pict_type\,PICT_TYPE_I)" -vsync 0 frame%03d.jpg
  
  </duration>

  That will get all I-frames from start_time through start_time+duration.

  But what I would like to do is give a list of frame numbers and have ffmpeg extract the closest key-frames to each frame-number. Is there a way to do this with ffmpeg or would I have to write my own program ontop of libavcodec to do this ?

• ffmpeg fails to connect to pulse audio when scheduled through cron

  4 février 2017, par Barrett

  I would like to start ffmpeg to capture audio from pulse through a cron task. I am currently running Linux arch 4.8.13-1-ARCH #1 SMP PREEMPT x86_64 GNU/Linux.

  $ ffmpeg

  ffmpeg version 3.2.2 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 6.2.1 (GCC) 20160830
  
    configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-avisynth --enable-avresample --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libass --enable-libbluray --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-netcdf --enable-shared --enable-version3 --enable-x11grab
  
    libavutil      55. 34.100 / 55. 34.100
  
    libavcodec     57. 64.101 / 57. 64.101
  
    libavformat    57. 56.100 / 57. 56.100
  
    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

  $ arecord -l

  **** List of CAPTURE Hardware Devices ****
  
  card 0: MID [HDA Intel MID], device 0: CX20583 Analog [CX20583 Analog]
  
    Subdevices: 1/1
  
    Subdevice #0: subdevice #0

  /usr/local/sbin/ffmpeg-audio

  #! /bin/sh
  
  SHELL=/bin/sh
  
  PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
  
  
  
  n=$(date +"%s")
  
  out="/home/user/audio/out"$n".mp3"
  
  
  
  cd /
  
  
  
  echo -e $USER" "$(id -u)"\n"$out"\n" > $out.txt
  
  
  
  /usr/bin/ffmpeg -y -f alsa -i pulse -t 5 -codec:a libmp3lame -q:a 9 "file:"$out

  $ crontab -l

  *   *   *   *   *   /usr/local/sbin/ffmpeg-audio

  $ journalctl -u cronie

  Feb 04 11:51:01 arch crond[8913]: pam_unix(crond:session): session opened for user user by (uid=0)
  
  Feb 04 11:51:01 arch CROND[8914]: (user) CMD (/usr/local/sbin/ffmpeg-audio)
  
  Feb 04 11:51:01 arch sudo[8919]:     user : TTY=unknown ; PWD=/ ; USER=root ; COMMAND=/usr/bin/ffmpeg -y -f alsa -i pulse -t 5 -codec:a libmp3lame -q:a 9 file:/home/user/audio/out1486237861.mp3
  
  Feb 04 11:51:01 arch sudo[8919]: pam_unix(sudo:session): session opened for user root by (uid=0)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (ffmpeg version 3.2.2 Copyright (c) 2000-2016 the FFmpeg developers)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  built with gcc 6.2.1 (GCC) 20160830)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-avisynth --enable-avresample --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libass --enable-libbluray --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-netcdf --enable-shared --enable-version3 --enable-x11grab)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libavutil      55. 34.100 / 55. 34.100)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libavcodec     57. 64.101 / 57. 64.101)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libavformat    57. 56.100 / 57. 56.100)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libavdevice    57.  1.100 / 57.  1.100)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libavfilter     6. 65.100 /  6. 65.100)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libavresample   3.  1.  0 /  3.  1.  0)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libswscale      4.  2.100 /  4.  2.100)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libswresample   2.  3.100 /  2.  3.100)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (  libpostproc    54.  1.100 / 54.  1.100)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (ALSA lib pulse.c:243:(pulse_connect) PulseAudio: Unable to connect: Connection refused)
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT ()
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT ([alsa @ 0x55a46e0144a0] cannot open audio device pulse (Connection refused))
  
  Feb 04 11:51:01 arch CROND[8913]: (user) CMDOUT (pulse: Input/output error)
  
  Feb 04 11:51:01 arch sudo[8919]: pam_unix(sudo:session): session closed for user root
  
  Feb 04 11:51:01 arch CROND[8913]: pam_unix(crond:session): session closed for user user

  ffmpeg runs correctly from the command line and ’$ which ffmpeg-audio’ returns /usr/local/sbin/ffmpeg-audio, but ffmpeg returns

  ([alsa @ 0x55a46e0144a0] cannot open audio device pulse (Connection
  refused))

  when scheduled through cron.

  Any suggestions ?

• Mix 2 mp3 files with FFmpeg for adroid

  1er avril 2017, par Thankgod Richard

  I am developing something similar to a karaoke app. I have a sound file(beat) and a recorded file(voice) from android mediarecorder. I am trying to mix the two files to become one file that plays the same time. I have set up ffmpeg provided by writingminds and everything is working fine. I am not familiar with ffmpeg commands so searched for and got few commands that can achieve the task for me. This is the code i got :

    String files = "-i " + currentFile + " -i " + someFile.getAbsolutePath();
  
              String output = mFileName + "/recorded/test.mp3";
  
              String cmd = "ffmpeg "+files+
  
                      " -filter_complex \"aevalsrc=0:d=10[s1];[s1][1:a]concat=n=2:v=0:a=1[ac1];[0:a][ac1]amix[aout]\" -map [aout] -c:a libmp3lame " + output;

  But it not working. this is the error i got :

  04-01 12:09:26.598 21300-21300/com.shixels.thankgodrichard.mixer I/fpeg : ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.8 (GCC)
  configuration : —target-os=linux —cross-prefix=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/bin/arm-linux-androideabi- —arch=arm —cpu=cortex-a8 —enable-runtime-cpudetect —sysroot=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/sysroot —enable-pic —enable-libx264 —enable-libass —enable-libfreetype —enable-libfribidi —enable-libmp3lame —enable-fontconfig —enable-pthreads —disable-debug —disable-ffserver —enable-version3 —enable-hardcoded-tables —disable-ffplay —disable-ffprobe —enable-gpl —enable-yasm —disable-doc —disable-shared —enable-static —pkg-config=/home/vagrant/SourceCode/ffmpeg-android/ffmpeg-pkg-config —prefix=/home/vagrant/SourceCode/ffmpeg-android/build/armeabi-v7a —extra-cflags=’-I/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/include -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-strict-overflow -fstack-protector-all’ —extra-ldflags=’-L/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/lib -Wl,-z,relro -Wl,-z,now -pie’ —extra-libs=’-lpng -lexpat -lm’ —extra-cxxflags=
  libavutil 55. 17.103 / 55. 17.103
  libavcodec 57. 24.102 / 57. 24.102
  libavformat 57. 25.100 / 57. 25.100
  libavdevice 57. 0.101 / 57. 0.101
  libavfilter 6. 31.100 / 6. 31.100
  libswscale 4. 0.100 / 4. 0.100
  libswresample 2. 0.101 / 2. 0.101
  libpostproc 54. 0.100 / 54. 0.100
  Output #0, mp3, to ’ffmpeg -i /storage/emulated/0/MyStudio/temps/1491044929409.mp3 -i /storage/emulated/0/temp.mp3 -filter_complex "aevalsrc=0:d=10[s1] ;[s1][1:a]concat=n=2:v=0:a=1[ac1] ;[0:a][ac1]amix[aout]" -map [aout] -c:a libmp3lame /storage/emulated/0/recorded/test.mp3’ :
  Output file #0 does not contain any stream
  04-01 12:09:26.599 21300-21300/com.shixels.thankgodrichard.mixer I/fpeg : finished

  I read some answers here saying it depends on the version of the ffmpeg your using. I am using the latest ffmpeg for android by writingminds.