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• Is there a way to generate ffmpeg command-lines by analyzing an existing video file ?

  24 décembre 2014, par PreservedMoose

  Is there a tool or technique that is able to generate a valid ffmpeg encode command, based on the properties of an existing source file ?

  In other words, I’d like to take an H264 QuickTime file, run it through the aforementioned (possibly) mythical tool, and have it spit out an ffmpeg command line that can be used to encode another video that matches the exact specs of the source file.

  Apple’s Compressor has similar functionality, where you can just drag a Quicktime file to the Compressor Presets window, and it will automatically create an encoding preset that matches the specs of that file.

  Is there a similar way to achieve this with ffmpeg ?

• Static image and a folder of mp3's ?

  28 juin 2013, par Shirohige

  I want to create a bunch of videos consisting of an single image which is shown throughout the whole video but each video has a different audio file. I can do it manually with various tools but the problem is that I have a lot of audio files and I can't optimize the frame rate (more on that later) and it takes a lot of time to do it that way but ffmpeg offers everything I need but the problem is that I don't know how to batch process everything.

  The basic code :
  ffmpeg -i song-name.mp3 -loop 1 -i cover.jpg -r frame-rate -t song-length -acodec copy output.mp4

  What I want to achieve :
  Let's say that I have a folder which consists of several audio files : song-name-1.mp3, song-name-2.mp3, ..., song-name-n.mp3 and cover.jpg.

  I need a batch file which takes the name of every mp3 file in a folder (a FOR loop I suppose) and processes it with the same command :
  ffmpeg -i song-name.mp3 -loop 1 -i cover.jpg -r frame-rate -t song-length -acodec copy output.mp4

  So the image is always the same for every video. The song length can be taken with the tool mp3info and the corresponding command :
  mp3info.exe -p %S song-name.mp3

  Since I only have one image throughout the whole video, the optimal frame rate would be the inverse of the video length which is 1/length (where length is a variable in seconds which we get from mp3info).

  So the final code should look something like this :
  ffmpeg -i song-name.mp3 -loop 1 -i cover.jpg -r 1/length -t length -acodec copy song-name.mp4

  Where "song-name" is a variable which changes for every iteration of the FOR loop (i.e. for every audio file in the folder) and length is a variable whose value we get with the command :
  mp3info.exe -p %S song-name.mp3

  I found examples of a FOR loop to fetch all file names of all mp3's in a specific folder but I do not know how to integrate mp3info. I hope that somebody can help me and I have some knowledge of the C programming language if that can be used in any way.

• ffmpeg frame rate issue h264+ass to mkv

  27 juin 2013, par user2529661

  I'm using this command for ffmpeg :

  ffmpeg  -i 1.h264 -i ass1.ass -map 0 -map 1 -c copy test.mkv

  The h264 file is 30 fps... the mkv plays at 25fps so it runs slow

  The h264 come off my hd webcam. If i change the frame rate on the camera to 25 it works fine and 15fps wilk play at high speed. I can force the frame rate ? Every if i need a different command line tool to change it that is acceptable. But if i could fix it form ffmpeg that would be ideal. I'm running the commands from vb.net.

  command output
  
  C:\Record\Normal\2013-06-27>c:\ffmpeg\bin\ffmpeg  -i 1.h264 -i ass1.ass -map 0 -
  
  map 1 -c copy test.mkv
  
  ffmpeg version N-54207-ge59fb3f Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jun 25 2013 21:55:00 with gcc 4.7.3 (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-libvo-aacenc --enable-libvo-
  
  amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --
  
  enable-libxvid --enable-zlib
  
    libavutil      52. 37.101 / 52. 37.101
  
    libavcodec     55. 17.100 / 55. 17.100
  
    libavformat    55. 10.100 / 55. 10.100
  
    libavdevice    55.  2.100 / 55.  2.100
  
    libavfilter     3. 77.101 /  3. 77.101
  
    libswscale      2.  3.100 /  2.  3.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, h264, from '1.h264':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: h264 (Baseline), yuv420p, 1920x1088 [SAR 1:1 DAR 30:17],
  
   25 fps, 25 tbr, 1200k tbn, 50 tbc
  
  Input #1, ass, from 'ass1.ass':
  
    Duration: N/A, bitrate: N/A
  
      Stream #1:0: Subtitle: ssa
  
  File 'test.mkv' already exists. Overwrite ? [y/N] y
  
  Output #0, matroska, to 'test.mkv':
  
    Metadata:
  
      encoder         : Lavf55.10.100
  
      Stream #0:0: Video: h264 (H264 / 0x34363248), yuv420p, 1920x1088 [SAR 1:1 DA
  
  R 30:17], q=2-31, 25 fps, 1k tbn, 1200k tbc
  
      Stream #0:1: Subtitle: ssa
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #1:0 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  frame=  144 fps=0.0 q=-1.0 Lsize=    2451kB time=00:00:05.72 bitrate=3509.6kbits
  
  /s
  
  video:2447kB audio:0kB subtitle:0 global headers:0kB muxing overhead 0.125529%