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• How to get the real, actual duration of an MP3 file (VBR or CBR) server-side

  27 janvier 2021, par SquareCat

  I used to calculate the duration of MP3 files server-side using ffmpeg - which seemed to work fine. Today i discovered that some of the calculations were wrong. Somehow, for some reason, ffmpeg will miscalculate the duration and it seems to happen with variable bit rate mp3 files only.

  



  When testing this locally, i noticed that ffmpeg printed two extra lines in green.

  



  Command used :

  



  ffmpeg -i song_9747c077aef8.mp3


  



  ffmpeg says :

  



  [mp3 @ 0x102052600] max_analyze_duration 5000000 reached at 5015510
[mp3 @ 0x102052600] Estimating duration from bitrate, this may be inaccurate


  



  After a nice, warm google session, i discovered some posts on this, but no solution was found.

  



  I then tried to increase the maximum duration :

  



  ffmpeg -analyzeduration 999999999 -i song_9747c077aef8.mp3


  



  After this, ffmpeg returned only the second line :

  



  [mp3 @ 0x102052600] Estimating duration from bitrate, this may be inaccurate


  



  But in either case, the calculated duration was just plain wrong. Comparing it to VLC i noticed that there the duration is correct.

  



  After more research i stumbled over mp3info - which i installed and used.

  



  mp3info -p "%S" song_9747c077aef8.mp3


  



  mp3info then returned the CORRECT duration, but only as an integer, which i cannot use as i need a more accurate number here. The reason for this was explained in a comment below, by user blahdiblah - mp3info is simply pulling ID3 info from the file and not actually performing any calculations.

  



  I also tried using mplayer to retrieve the duration, but just as ffmpeg, mplayer is returning the wrong value.

  


• How to achieve real time video editing on Android ?

  3 octobre 2024, par Itamar

  I've been working recently on a video-editing-related project on Android, and am desperately looking for resources related to video editing on the platform.

  


  The only video-editing related "method" or information I could find was using the FFmpeg library, which is pretty rich in features and capabilities but works really slow, operations such as reversing a 10-second video can take as long as 30 seconds, which delivers a really poor user experience.

  


  That being said, it seems that there are tons of Android video-editing apps that are capable of doing everything FFmpeg can, only in almost immediate periods of time (apps such as InShot, PocketVideo or even the previous musical.ly TikTok).

  


  I've tried researching and searching for information on the topic in almost any reasonable place (Google, GitHub, YouTube, the Android developer center, and even on "support" pages of the above-mentioned apps) to no avail (no explanatory documents, no open source libraries, not even demo apps), if anyone could shed some light on the subject that would be much, much appreciated !

  


  Thanks.

  


• ffmpeg 1 image (JPG) + 1 audio file (MP3) = 1 video (WEBM) using real encode (-re)

  27 janvier 2015, par Gabriel Viana Passos

  I’d like to make video streaming to distribute it in a streaming.
  The mp3 file is being extracted from a video file (which is being recorded live) and, while audio being extracted (MP3), I want to take this audio file and a image it and spread it in a real time streaming. But -re is not working for this.

  To extract audio file i use :

  ffmpeg.exe -re -i file(LIVE).AVI -vn -ar 22050 -ab 16k -r 1 -ac 1 -f mp3 C:\Users\" & wshNetwork.Username & "\Documents\audio.mp3"

  This work very well to make the MP3 file. Using -re.

  After that, I’m using this command to marge the auvio file with the jpg image :

  ffmpeg.exe -loop 1 -f image2 -i c:\picture.jpg -re -i c:\Users\" & wshNetwork.Username & "\Documents\audio.mp3 -vb 10k -ar 22050 -ab 16k -ac 1 -r 1 -bufsize 300k -f webm www.adress.com

  This second command is not working because the -re is not working, and produce a video with the picture and a choppy audio.

  the output is :

  ffmpeg version N-63113-g72dcd48 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on May 12 2014 22:10:08 with gcc 4.8.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetyp
  
  e --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --ena
  
  ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l
  
  ibopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libsp
  
  eex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aa
  
  cenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavp
  
  ack --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable
  
  -decklink --enable-zlib
  
    libavutil      52. 83.100 / 52. 83.100
  
    libavcodec     55. 61.100 / 55. 61.100
  
    libavformat    55. 37.102 / 55. 37.102
  
    libavdevice    55. 13.101 / 55. 13.101
  
    libavfilter     4.  5.100 /  4.  5.100
  
    libswscale      2.  6.100 /  2.  6.100
  
    libswresample   0. 18.100 /  0. 18.100
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, image2, from 'c:\imagens\radiobb.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: mjpeg, yuvj420p(pc), 553x342 [SAR 96:96 DAR 553:342], 25
  
   fps, 25 tbr, 25 tbn, 25 tbc
  
  [mp3 @ 0000000002b8f660] Estimating duration from bitrate, this may be inaccurat
  
  e
  
  Input #1, mp3, from 'C:\Users\f3548956\Documents\audio.mp3':
  
    Metadata:
  
      encoder         : Lavf55.37.102
  
    Duration: 00:00:09.34, start: 0.050113, bitrate: 16 kb/s
  
      Stream #1:0: Audio: mp3, 22050 Hz, mono, s16p, 16 kb/s
  
  [swscaler @ 0000000002ae1640] deprecated pixel format used, make sure you did se
  
  t range correctly
  
  [libvpx @ 0000000002a8da40] v1.3.0
  
  Output #0, webm, to 'http://172.17.146.***:8080/publish/tvbb100?password=****'
  
  :
  
    Metadata:
  
      encoder         : Lavf55.37.102
  
      Stream #0:0: Video: vp8 (libvpx), yuv420p, 553x342 [SAR 1:1 DAR 553:342], q=
  
  -1--1, 10 kb/s, 1k tbn, 25 tbc
  
      Stream #0:1: Audio: vorbis (libvorbis), 22050 Hz, mono, fltp, 16 kb/s
  
  Stream mapping:
  
      Stream #0:0 -> #0:0 (mjpeg -> libvpx)
  
      Stream #1:0 -> #0:1 (mp3 -> libvorbis)
  
      Press [q] to stop, [?] for help
  
      frame=   33 fps=0.0 q=0.0 size=     4kB time=00:00:01.32 bitrate=  23.3kbits/s
  
      frame=   67 fps= 66 q=0.0 size=     4kB time=00:00:02.68 bitrate=  11.5kbits/s
  
      frame=  101 fps= 66 q=0.0 size=    11kB time=00:00:04.04 bitrate=  22.4kbits/s
  
      frame=  133 fps= 66 q=0.0 size=    11kB time=00:00:05.32 bitrate=  17.0kbits/s

  Can anybody help me ?