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• FFMPEG Concat Demuxer adds more time to video than expected

  5 septembre 2023, par Shreyas

  I am using ffmpeg concat demuxer to join multiple(189) videos together.
The videos are originally split from a single video using the following command :

  


  ffmpeg -ss time[2] -vsync 1 -copyts -i inputfile.mp4 -ss time[0] -to time[1] -c:a copy -c:v libx264 -b:v 800k output.mp4


  


  Thereafter I am using the following concat command :

  


  ffmpeg -f concat -safe 0 -i list.txt -c copy output.mp4


  


  The problem is that the sum of the lengths of the input videos is 24:03:520
The output.mp4 video comes out to be 24:05:550.
Which is two seconds longer than the constituent video length.

  


  I need the output video to be time accurate. How can I achieve this without reencoding the video ?

  


• ffmpeg php video basic uses and types

  15 mai 2014, par HackerManiac

  Can anyone give a code on how do i covert a video using ffmpeg.

  As thought currently i have only uploading system.

  vu.php(only a part is shown)

  define('UPLOAD','../../videos/');
  
      $fileName = time().$file['name']; 
  
      $target = UPLOAD.$fileName;
  
  
  
    if(move_uploaded_file($file['tmp_name'],$target)){                
  
        exec("ffmpeg -i ".UPLOAD." ".UPLOAD.$filename.".flv"); 
  
    }

  This pice of code block just uploads the video on video folder but does not converts it to .flv.
  I am not sure how to use ffmpeg.

  My diretory looks like this

  www[localhost]->videos[videos folder]
  
  www[localhost]->pictures[pictures folder]
  
  www[localhost]->resources[folder]->php[folder]->vu.php

  I also want to return a .jpg image of any frame of video through json by converting via ffmpeg and uploading it to pictures folder.

  return json_encode(array("thumbnail"=>$image_src));

  UPDATE 1

  The above stuff was solved but now i have a question regarding video conversion.
  Suppose i have a file.avi and i want to convert it in 3 sizes of .flv format -> Low(320p) ,Medium (720p)and HD(1080p)

  what commands will i have to send to shell_exec(); and will that be fast enough ?
  CUrrently what i have is

  $vidSize = "640x480";
  
  $ffmpeg -i $videoFile -ar 22050 -ab 32 -f flv -s $vidSize $vidFile

  And i am not sure what -ar and -ab means and what value will be good for all those 3 sized videos ?

• After transcoding using ffmpeg, I found audio bitrate is not the value I expected

  16 mai 2017, par penny

  I used ffmpeg to transcode some files into new format and with certain parameters. After transcoding, I found some output file’s metadata is not what I expected, the output value is not the same with I set in the cmd line.

  Before transcoding I check the media info of the inputfile :

  ffmpeg -i dz2015082000010.mpg

  ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.8.3 (GCC) 20140911 (Red Hat 4.8.3-9)
  configuration : —enable-static —enable-memalign-hack —enable-libx264
  —enable-gpl —enable-pthreads —enable-version3 —enable-avisynth —enable-bzlib —enable-iconv —enable-zlib —enable-nonfree —extra-cflags=-I/usr/local/include/ —extra-ldflags=-L/usr/local/lib —enable-debug=3 —disable-optimizations —enable-nonfree —enable-libmp3lame libavutil 55. 34.101 / 55. 34.101 libavcodec 57. 64.101 / 57. 64.101 libavformat 57. 56.101 /
  57. 56.101 libavdevice 57. 1.100 / 57. 1.100 libavfilter 6. 65.100 / 6. 65.100 libswscale 4. 2.100 / 4. 2.100 libswresample 2. 3.100 / 2. 3.100 libpostproc 54. 1.100 /
  54. 1.100 Input #0, mpeg, from ’dz2015082000010.mpg’ : Duration : 00:01:49.30, start : 0.685389, bitrate : 15723 kb/s
  Stream #0:0[0x1e0] : Video : mpeg2video (Main), yuv420p(tv, top first), 1920x1080 [SAR 1:1 DAR 16:9], 15000 kb/s, 25 fps, 25 tbr,
  90k tbn, 50 tbc
  Stream #0:1[0x1c0] : Audio : mp2, 48000 Hz, stereo, s16p, 384 kb/s At least one output file must be specified

  Next, transcoding with the cmd line :

  ffmpeg -i dz2015082000010.mpg -vcodec libx264 -b:v 4000k -s 1920x1080 -r 25 -g 25  -vprofile main -acodec aac -strict -2 -b:a 128k -ac 2 -ar 44100 -y output.ts

  After transcoding, I check the media info of the output file :

  ffmpeg -i output.ts    

  ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers built with gcc 4.8.3 (GCC) 20140911 (Red Hat
  4.8.3-9) configuration : —enable-static —enable-memalign-hack —enable-libx264 —enable-gpl —enable-pthreads —enable-version3 —enable-avisynth —enable-bzlib —enable-iconv —enable-zlib —enable-nonfree —extra-cflags=-I/usr/local/include/ —extra-ldflags=-L/usr/local/lib —enable-debug=3 —disable-optimizations —enable-nonfree —enable-libmp3lame libavutil 55. 34.101 / 55. 34.101 libavcodec 57. 64.101
  / 57. 64.101 libavformat 57. 56.101 / 57. 56.101
  libavdevice 57. 1.100 / 57. 1.100 libavfilter 6. 65.100
  / 6. 65.100 libswscale 4. 2.100 / 4. 2.100
  libswresample 2. 3.100 / 2. 3.100 libpostproc 54. 1.100
  / 54. 1.100 Input #0, mpegts, from ’full-2.ts’ : Duration :
  00:01:49.30, start : 1.456778, bitrate : 4455 kb/s Program 1
  Metadata :
  service_name : Service01
  service_provider : FFmpeg
  Stream #0:0[0x100] : Video : h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr,
  90k tbn, 50 tbc
  Stream #0:1[0x101] : Audio : aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 4 kb/s At least one output file must be
  specified

  I don’t know why the audio bitrate is changed to 4 kb/s after transcoding, I set the value with -b:a 128k before, anybody can help me ? BTW, the output file sounds all right.