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• Is there a way to speed up audio processing (amix and adelay) in FFMPEG ?

  30 mars 2017, par Nadir

  I’m using, in android application, many ffmpeg amix and adelay filter commands over very small mp3 files (not longer than 3 seconds).
  Unfortunately each adelay or amix command takes between 2 and 4 seconds to execute, which is a lot considering that I should run the same operation for a lot of files.
  Here are two example of commands I’m running :

  amix :

  [-i, input1.mp3, -i, input2.mp3, -filter_complex, amix=inputs=2:duration=longest:dropout_transition=0,dynaudnorm=f=100[aout], -map, [aout], -ac, 2, -c:a, libmp3lame, -q:a, 4, output.mp3]

  adelay :

  [-i, input3.mp3, -filter_complex, [0:a]adelay=1|1, -c:a, libmp3lame, output1.mp3]

  I know in video there is an option (-preset ultrafast) to make the execution faster, is there a way to do the same for audio ?

• FFMPEG being killed when processing H264 video

  4 mai 2017, par Stuart Clarke

  I have a program that when given a video (video.mp4), extracts the audio, a thumbnail image and the video into separate files, adds some background music to the audio file to create a new file (combined.mp3), increases the resolution of the video to 1080p and saves to a new file (videoHD.mp4), adds intro and credits to the start and end (already in 1080p) and saves that to a new file (merged.mp4) and finally combines the processed video and audio into an output file (videoExt.mp4). I’m using ffmpeg through python and subprocess.call to do all this but the raw ffmpeg commands are as follows.

  ffmpeg -y -i video.mp4 -acodec mp3 audioTrack.mp3
  
  
  
  ffmpeg -y -ss 00:00:00 -i video.mp4 -vframes 1 -q:v 2 thumb.jpg
  
  
  
  ffmpeg -y -i video.mp4 -an videoTrack.mp4
  
  
  
  ffmpeg -y -i audioTrack.mp3 -i musicTrack.mp3 -filter_complex amerge -c:a libmp3lame -q:a 4 combined.mp3
  
  
  
  ffmpeg -y -i videoTrack.mp4 -vf 'scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:x=(1920-iw)/2:y=(1080-ih)/2:color=black' videoHD.mp4
  
  
  
  ffmpeg -y -f concat -i vids.ini -an merged.mp4
  
  
  
  ffmpeg -y -i merged.mp4 -i combined.mp3 -strict -2 -shortest videoExt.mp4

  Between extracting the audio and combining with the music I add a silent period matching the intro length to the beginning for the audio and lower the volume of the music for the duration of the video section and crop the music to the length of the combined intro, video and credits. This is all done with AudioSegment and works well.

  My problem is that the ffmpeg process keeps being killed. It happens in various places at various times, but always when processing the video at 1080p. I’m sure it has something to do with the H264 codec but when I use mpeg4 the quality is terrible. The videos are always less than a minute (Instagram videos) and at most 25Mb, I’m using a VPS with Ubuntu Server 15.04 installed, it should be able to handle this surely. If not is there a way around it, processing the video in parts ?

  Here is an example of the error but as I said, it can happen in various places and sometimes will complete for one command but I have never had it complete for all.

  # ffmpeg -y -f concat -i vids.ini -an merged.mp4
  
  
  
  ffmpeg version 2.5.10-0ubuntu0.15.04.1 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 4.9.2 (Ubuntu 4.9.2-10ubuntu13)
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.15.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --shlibdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --enable-shared --disable-stripping --enable-avresample --enable-avisynth --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-libopus --enable-libpulse --enable-libschroedinger --enable-libshine --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libwavpack --enable-libwebp --enable-libxvid --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzvbi --enable-libzmq --enable-frei0r --enable-libvpx --enable-libx264 --enable-libsoxr --enable-gnutls --enable-openal --enable-libopencv --enable-librtmp --enable-libx265
  
    libavutil      54. 15.100 / 54. 15.100
  
    libavcodec     56. 13.100 / 56. 13.100
  
    libavformat    56. 15.102 / 56. 15.102
  
    libavdevice    56.  3.100 / 56.  3.100
  
    libavfilter     5.  2.103 /  5.  2.103
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, concat, from 'vids.ini':
  
    Duration: N/A, start: 0.000000, bitrate: 2999 kb/s
  
      Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 2996 kb/s, 29.97 fps, 29.97 tbr, 11988 tbn, 59.94 tbc
  
      Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 2 kb/s
  
  [libx264 @ 0x134fd00] using SAR=1/1
  
  [libx264 @ 0x134fd00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x134fd00] profile High, level 4.0
  
  [libx264 @ 0x134fd00] 264 - core 142 r2495 6a301b6 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'merged.mp4':
  
    Metadata:
  
      encoder         : Lavf56.15.102
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
  
      Metadata:
  
        encoder         : Lavc56.13.100 libx264
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  
  Press [q] to stop, [?] for help
  
  frame=   13 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A dup=1 dro
  
  frame=   28 fps= 27 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A dup=1 dro
  
  frame=   46 fps= 21 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A dup=1 dro
  
  frame=   51 fps= 16 q=29.0 size=     120kB time=00:00:00.-3 bitrate=N/A dup=1 dr
  
  frame=   55 fps= 15 q=29.0 size=     154kB time=00:00:00.10 bitrate=12574.5kbits
  
  frame=   60 fps= 14 q=29.0 size=     195kB time=00:00:00.26 bitrate=5981.0kbits/
  
  frame=   65 fps= 13 q=29.0 size=     254kB time=00:00:00.43 bitrate=4797.0kbits/
  
  frame=   69 fps= 12 q=29.0 size=     287kB time=00:00:00.56 bitrate=4142.1kbits/
  
  frame=   73 fps= 12 q=29.0 size=     375kB time=00:00:00.70 bitrate=4384.2kbits/
  
  frame=   76 fps= 11 q=29.0 size=     418kB time=00:00:00.80 bitrate=4278.4kbits/
  
  frame=   81 fps= 11 q=29.0 size=     441kB time=00:00:00.96 bitrate=3732.4kbits/
  
  frame=   85 fps= 10 q=29.0 size=     472kB time=00:00:01.10 bitrate=3511.0kbits/
  
  Killed1 drop=0 

  Any ideas or if anyone knows a better way to this please let me know.

  Cheers,

  Stu

• Is it possible to be notified each time ffmpeg finish processing one of multiple outputs ?

  8 juin 2017, par Marcos Pinazo

  I am trying to use a single ffmpeg command to encode a streaming url and generate many output files. In this example, ffmpeg will output three files of duration 5, 10 and 15 seconds :

  ffmpeg -i <url> \
  
   -t  5 output_5.wav \
  
   -t 10 output_10.wav \
  
   -t 15 output_15.wav \
  
  </url>

  The command works as expected, but I need to know when each one of the output files is available, in order to start further processing as soon as possible.

  Is there any way to be notified of each one of the events "file output_XX.wav is ready" ?

  One approach I have tried is to use inotifywatch to listen for CLOSE events, but I have found that ffmpeg only closes the files when the last one ends.

  I could also listen for MODIFY events but there is no way to know when ffmpeg is done, I can only guess it by testing against a hardcoded maximum file size (very nasty solution !).