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• Using ffmpeg to display a static image if an RTMP input source is missing

  19 mars 2016, par iameli

  Here is what I would like ffmpeg to output :

  • If I am streaming from my iPhone to my RTMP server, ffmpeg should output the live video from my iPhone.
  • If not, ffmpeg should output a blank red screen.

  Here’s what I have so far. It sort of works.

  ffmpeg \
  
    -f lavfi \
  
    -re \
  
    -i 'color=s=320x240:r=30:c=red' \
  
    -thread_queue_size 512 \
  
    -i 'rtmp://localhost/stream/iphone' \
  
    -c:v libx264 \
  
    -f flv \
  
    -filter_complex "\
  
      [1:v]scale=320:240[stream]; \
  
      [0:v][stream]overlay=0:0:eof_action=pass[output] \
  
    "\
  
    -map '[output]' \
  
    -tune zerolatency \
  
    'rtmp://localhost/stream/output'

  What happens : it boots up and starts streaming my iPhone’s output no problem. When I disconnect, it hangs for a long time, perhaps 20 seconds. Then it starts outputting red, okay. But then if I reconnect my phone, it doesn’t resume. It’s still red. Two questions :

  • Is there a way to configure the buffering so that it starts outputting red as soon as it stops getting data from the RTMP stream ?
  • Is there a way to have it auto-retry, so after the RTMP stream returns, it will switch back ?

  Full verbose output, if that’s helpful. I’m using the latest git version of ffmpeg as of 2016-03-18 on Ubuntu Wily. The RTMP server is nginx-rtmp.

• FFMPEG - Use Orientation metadata for mobile recordings

  21 mai 2012, par Kim Egede Jakobsen

  When I convert a .mov file recorded on a iPhone 4S, the video is rotated 180 degrees.
  If I playing the video on my computer, it looks correct.

  I got the same issue with .3gp files from Android and .mov from iPhone 4 (They are rotated 90 degrees)

  I have tried looking in the documentation for FFMPEG, but it seems that I will need to scan the metadata and then add it to my convertion script ?

  Command tried : ffmpeg -i VID_20120510_104204.mov -y -f flv -ar 44100 VID_20120510_104204.flv
  Also looked on -vf %ROTATE%

• dts to m4a (aac) encoding - qaac, neroaacenc encoder output issues

  9 avril 2014, par user8979

  greets

  I want to encode a dts 5.1 audio source to m4a (aac) 5.1 with same playback duration.
  Intend to use either qaac or neroAacEnc.

  The output is the same per encoder with .mkv and .dts extracted from .mkv as input audio source.
  .mkv source piped to encoder using ffmpeg
  .dts source piped to encoder using ffmpeg and wavi with .avs input, .avs using NicAudio avisynth plugin, to decode .dts source for separate encodes to confirm if challenges encountered were from ffmpeg or elsewhere (both produced the same issues so concluded the issues originated from the respective encoders)

  • qaac output is same duration as .mkv
    issues : mediainfo reports output is 2ch while mediatab and ffmpeg report output is 5.1ch (lfe)

    mediainfo :

    Channel(s) : 2 channels
    Channel(s)_Original : 6 channels
    Channel positions : Front : L C R, Side : L R, LFE
    this channel position and channel combination is not possible, so which is it ?

    ffmpeg (5.1 info bold) :

    Stream #0:0(und) : Audio : aac, 5.1, fltp

    mediatab :

    Channel(s) : 6 channels
    ChannelPositions : Front : L C R, Side : L R, LFE

  • neroaacenc output has same channels, 5.1
    issue : ffmpeg reports output is longer than mkv audio track by 0.06 seconds (60 ms) and it begins after 0.054677 seconds (54.667 ms)

    Chapter #0.0 : start 0.054667

  Questions :

  1. qaac output
     
     • is the output stream 2ch or 5.1ch ?
     • if it is 2ch, what qaac option(s) leave the channels in output same as input AND report the correct channels ?
     • if the output is 5.1ch, does this mean every qaac output keeps the input channels (without using —chanmap or other such options) ? if so then its easy to ignore mediainfo channel information for qaac encodes.
       
       • why did mediainfo report 2ch ? could the stream report incorrect channels to a media player (implies incorrect playback) ? is there any way to get rid of the misleading channel information shown in mediainfo ? (expecting the information to be stored in the file, that is where would like to get rid of it)
  2. neroaacenc output
     • how can one ensure neroaacenc output is exact same duration as input ?
     • if not possible to change the output duration, does that mean when muxing audio with video, include the 54.667 ms delay to maintain sync ? (audio delay of -0.054667 s in this case) ?

  Commandlines were many so not included. Let me know if they would be helpful.