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• Find out what device to use for capturing with ffmpeg ?

  14 septembre 2013, par wvxvw

  I'm trying to broadcast my screen and I cannot capture audio. There's one complication however. I don't have pulseaudio, and it simply doesn't work on my system, so installing it is out of question. Below is the command I'm trying :

  ffmpeg -f alsa -i ??? -f x11grab -s 1920x1200 -r 15 -i :0.0 \
  
      -acodec pcm_s16le -vcodec libx264 \
  
      -preset fast -pix_fmt yuv420p -s 1280x800 -threads 0 -f flv "$URL"

  Here's the list of my audio devices :

  $ aplay -L
  
  null
  
      Discard all samples (playback) or generate zero samples (capture)
  
  default:CARD=PCH
  
      HDA Intel PCH, ALC269VB Analog
  
      Default Audio Device
  
  sysdefault:CARD=PCH
  
      HDA Intel PCH, ALC269VB Analog
  
      Default Audio Device
  
  front:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      Front speakers
  
  surround40:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      4.0 Surround output to Front and Rear speakers
  
  surround41:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      4.1 Surround output to Front, Rear and Subwoofer speakers
  
  surround50:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      5.0 Surround output to Front, Center and Rear speakers
  
  surround51:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      5.1 Surround output to Front, Center, Rear and Subwoofer speakers
  
  surround71:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
  
  iec958:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Digital
  
      IEC958 (S/PDIF) Digital Audio Output
  
  hdmi:CARD=NVidia,DEV=0
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output
  
  hdmi:CARD=NVidia,DEV=1
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output
  
  hdmi:CARD=NVidia,DEV=2
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output
  
  hdmi:CARD=NVidia,DEV=3
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output

  I know that ??? should be something like hw:X,Y, but maybe it can be something else. I can't find the corresponding entry in the man page.

  As an aside, it would be great if you can suggest another audio codec. I can't find what are the options, and this particular one isn't compatible with FLV because of too high bitrate.

  PS. This is the error I'm getting :

  Could not write header for output file #0 (incorrect codec parameters ?): Invalid data found when processing input

• laravel ffmpeg upload video in amazon s3 failed 504 gateway Time-out

  21 mai 2020, par Ahmed Al-Rayan

  Why after uploading a video size of more than 1 Giga, I see a problem in the nginx 504 gateway timeout preventing me from completing the processing process. The meaning of the video after uploading starts the processing process and because of this problem it does not go to processing use laravel ffmpeg and use amazon s3 service to store the videos on it and the entire site uploaded to Digital hosting

  


• Video Feedback Loop with ffmpeg

  4 mai 2020, par driangle

  I am trying to create a digital video feedback loop between two computers.

  



  What I mean by this is the following :

  



  

  



  I attempted several combinations of protocols and video formats and I found out this is the closest I can get. The original video was an "mov" but I had to convert it to .ts in order to get this far, had other issues when using mov or mp4.

  



  I ran the commands in this order to make sure tcp listeners were up before the clients.

  



  On Local Computer

  



  # Command 1: Temporary attempt to capture output of loop
ffmpeg -i 'udp://0.0.0.0:6002?listen&overrun_nonfatal=1' -c copy out.ts


  



  # Command 2: Receives stream from remote host and forwards back to beginning of loop
ffmpeg -i tcp://0.0.0.0:6001?listen -f mpegts udp://localhost:6002


  



  On Remote Computer

  



  #  Command 3: Receives stream from local host and returns stream to another ffmpeg instance
ffmpeg -i tcp://0.0.0.0:6000?listen -f mpegts tcp://:6001


  



  On Local Computer

  



  # Command 4: Sends stream to remote host
ffmpeg -re -i in.ts  -f mpegts tcp://:6000


  



  The steps above don't quite complete the feedback loop, but they do result in a successful video out.ts

  



  Then I tried to modify Command 4 so that it could merge both a file and a udp stream, this is a naive attempt I know, I am not very good with ffmpeg.

  



   ffmpeg \
    -re -i in.ts -i udp://0.0.0.0:6002 \
    -filter_complex " \
        [0:v]setpts=PTS-STARTPTS, scale=540x960[top]; \
        [1:v]setpts=PTS-STARTPTS, scale=540x960, \
             format=yuva420p,colorchannelmixer=aa=0.5[bottom]; \
        [top][bottom]overlay=shortest=1" \
    -f mpegts tcp://:6000


  



  The result was that the command hung waiting for a data on the udp port, which makes sense in hindsight.

  



  I would like to know :

  



  

  • Can this be done at all ? If so, what do I need to change ?

  


  • Do I need to abandon ffmpeg for this task and look into something else ?

  


  



  If you're asking why would I do this, the answer is there is no good reason other than I am curious to know if it's possible and what results it would yield.