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• TV audio extracted using ffmeg does not work in iOS (but it works in the simulator)

  26 janvier 2014, par Genar

  I can process a TV signal (well I have a .ts video which comes from a TV channel), using ffmpeg but the audio cannot be understood in an iPhone/iPad. The most strange is that the audio (and video) works properly in the simulator (and also in an Android real device, but this is another point), but in a real iPhone/iPad device the video is OK but the audio sounds like a metallic box and nothing can be understood.

  I have created the ffmpeg libraries for iOS (I have tried the version 2.0.2 and also the version 2.1.3) using the information provided in the following link :

  Installing ffmpeg ios libraries armv7, armv7s, i386 and universal on Mac with 10.8

  The aforementioned link explains how to create the ffmpeg include folders and the universal libraries which I have included into my project (the libraries created are : libavcodec.a, libavdevice.a, libavfilter.a, libavformat.a, libavresample.a, libavutil.a, libswresample.a and libswscale.a).

  The sampling frequency used is 48000.

  The audio got from ffmpeg is then stored into a buffer and then "inserted" using OpenAL ; but, from the same TV content (the same .ts video file) the audio data which is generated from ffmpeg in an iPhone/iPad is totally different from the audio data generated from ffmpeg in the simulator (which can reproduce both the audio and video perfectly).

  Thanks in advance,

• Using Coldfusion's CFFILE tag to monitor a progress log from FFMpeg

  5 mai 2013, par user1493918

  I want to learn how to use the CFFILE tag from ColdFusion to read the contents of a text file. In my case, that text file is a progress log that is generated by FFMpeg while it transcodes a media file. I want to write a ColdFusion script that will poll the progress log periodically, until the log indicates that FFMpeg has finished its transcoding operation. On the client side I can then use Ajax to hit that ColdFusion script and show the user a "percentage completed" while FFMpeg does its work.

  I got FFMpeg to generate the log file by using a new "progress" flag that recent versions of FFMpeg now support. Below I'll show you the way to use this flag, and also the generated output within the log file.

  Here's the FFMpeg command :

  ffmpeg -i c:\my_original_file.ogg c:\my_converted_file.mp3 -progress c:\my_progress.txt

  The above command will cause FFMpeg to generate a log file called my_progress.txt.

  Here's what it generates in the log file :

  total_size=206150
  
  out_time_ms=51410044
  
  out_time=00:00:51.410044
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue

  The above 6 lines are generated repeatedly in the log file, with increasing values.

  total_size=206150
  
  out_time_ms=51410044
  
  out_time=00:00:51.410044
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue
  
  total_size=412413
  
  out_time_ms=102975756
  
  out_time=00:01:42.975756
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue
  
  total_size=618363
  
  out_time_ms=154463111
  
  out_time=00:02:34.463111
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue
  
  total_size=824939
  
  out_time_ms=206107189
  
  out_time=00:03:26.107189
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue

  Finally, when the job completes, the final block of 6 lines are the last ones in the log file. Notice the "progress=end" on the last line :

  total_size=9725902
  
  out_time_ms=2431348011
  
  out_time=00:40:31.348011
  
  dup_frames=0
  
  drop_frames=0
  
  progress=end

  I want to write a Coldfusion script using the CFFILE tag to read only the last 6 lines of the file (no matter how large the file has become), and to do this each time the script is called, by the browser, via Ajax. Finally I need to parse the values on these lines into variables so I can return some data to the caller.

  I've researched progress bars for FFMpeg but they're in PHP which is hard for me, and besides, they parse the older formatted versions of FFMpeg's log files, and I would like to use the above newer formatting. Can anyone please help ?

• Why DASH video fragments are not reproducible nor readable with ffmpeg ?

  21 mai 2020, par salgarji

  I'm streaming live video using DASH through FFmpeg. Everything's OK, fragments are generated, and the mpd file, but I wanted to have reproducible independent fragments. Video players won't open those fragments. I guess it's because they are mpd file dependant. My question would be : can those fragments be generated in a way that they are reproducible ? I don't know if it has something to do to the frames I P B or just the way dash cuts video information, in a way that it only saves 'timeline' on the mpd...

  



  My purpose is not only being able to reproduce them sepparately, but I need to insert information in a metadata tag of the video, and ffmpeg won't let me read those live streaming generated fragments.

  



  FFmpeg input information command will behave like this :

  



  input :

  



  ffmpeg -i /path/video0-0-1.mp4


  



  output :

  



  ffmpeg version N-97777-g3b5a36c56d Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.59)
  configuration: --enable-gpl --enable-libx264
  libavutil      56. 45.100 / 56. 45.100
  libavcodec     58. 84.100 / 58. 84.100
  libavformat    58. 43.100 / 58. 43.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 81.100 /  7. 81.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fb324009400] could not find corresponding track id 1
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fb324009400] could not find corresponding trex (id 1)
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fb324009400] could not find corresponding track id 0
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fb324009400] trun track id unknown, no tfhd was found
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fb324009400] error reading header
/path/video0-0-1.mp4: Invalid data found when processing input


  



  I execute this FFmpeg code using fluent-ffmpeg over JS to generate the fragments :

  



  var ffmpeg = require('fluent-ffmpeg');

var grabacion = new ffmpeg();

grabacion.addInput('0')
.inputOptions(['-y -nostdin', '-f avfoundation', '-video_size 1280x720', '-pix_fmt nv12', '-framerate 30'])
.outputOptions(['-vcodec libx264', '-keyint_min 0', '-g 100', '-map 0:v', '-b:v 1000k', '-f dash',
 '-use_template 1', '-use_timeline 0', '-init_seg_name video0-$RepresentationID$-$Number$.mp4',
 '-media_seg_name video0-$RepresentationID$-$Number$.mp4', '-remove_at_exit 0', '-window_size 20', '-seg_duration 4'])
.output('/path/path/path/video.mpd')
.run();


  



  So, the final purpose would be to be able to insert a tag like this :

  



  ffmpeg -i video0-0-0.mp4 -movflags use_metadata_tags -metadata sample_tag=whateveryouwanttoadd video0-0-0-tagged.mp4


  



  Is there any way to do it ? Thank you in advance !