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• How can combine two separate scripts being piped together to make one script instead of two ?

  27 mars 2016, par user556068

  For the past couple hours I’ve been banging my head against the wall trying to figure out something I thought would be simple. Maybe it is but it’s beyond me at the moment. So I have now two scripts. Originallly they were part of the same but I could never make it work how it should. So the first part uses curl to download a file from a site. Then using grep and sedto filter out the text I need which is then put into a plain text file as a long list of website urls ; one per line. The last part of the 1st script calls on youtube -dl to read the batch file in order to obtain the web addresses where the actual content is located. I hope that makes sense.

  youtube-dl reads the batch file and outputs a new list urls into the terminal. This second list is not saved to file because it doesn’t need to be. These urls change from day to day or hour to hour. Using the read command, these urls are then passed to ffmpeg using a predetermined set of arguments for the input and output. Ffmpeg is executed on every url it receives and runs quietly in the background.

  The first paragraph describes script1.sh and paragraph 2 obviously describes script2.sh. When I pipe them together like script1.sh | script2.sh it works better than I ever thought possible. Maybe i’m nitpicking at this point but the idea is to have 1 unified script. For the moment I have simplified it by adding an alias to my .bash_profile.

  Here are the last two commands of script1.

  sed 's/\"\,/\//g' > "$HOME/file2.txt";
  
  cat $HOME/file2.txt | youtube-dl --ignore-config -iga -

  The trailing - allows youtube-dl to read from stdin.

  The second part of the script ; what I’m calling script2 at this point begins with

  while read -r input
  
  do
  
  ffmpeg [arg] [input] [arg2] [output]

  What am i not seeing that is causing the script to hang when the two halves are combined yet work perfectly if one is piped into the other ?

• Video delay when using filters in ffmpeg

  6 avril 2016, par Marcin

  I try to make video of sport event using raspberry pi. Drawtext filter seems good option to write score on the video.

  I have problem with synchronization / delay of video. I can see changing points few seconds before moment of score a point.

  for example, 30 seconds after start a record video I change points and wave hand to camera. I can see new text value immediately, but moment of wave hand is after at least 10 seconds.

  ffmpeg -threads 2 -f v4l2 -s 1280x720 -input_format h264 -i /dev/video0 \
  
    -filter_complex "[0:v]
  
          drawtext=reload=1:box=0:borderw=1:fontsize=36:fontcolor=White:fontfile=font/FreeSans.ttf:x=w/2-text_w/2-70:y=15:textfile=data/0.txt,
  
          drawtext=reload=1:box=0:borderw=1:fontsize=36:fontcolor=White:fontfile=font/FreeSans.ttf:x=w/2ïtext_w/2:y=15:textfile=data/1.txt" \
  
      -copyinkf -codec copy \
  
      -deinterlace -vcodec libx264 -crf 30 -pix_fmt yuv420p -preset ultrafast -qp 0 -r 30 -q 30 -minrate 800k -maxrate 800k \
  
      -tune zerolatency \
  
      -acodec aac -ab 128k -g 50 -strict experimental -f flv r.flv -y

  Another strange thing. I record video for 60 seconds and quit process by press "q" key and result video has only 42 seconds of length. Why ?

  See screen : speed of recording video ?

• Is it possible to capture audio from an ASIO device with ffmpeg ?

  26 mai 2016, par Amfasis

  We have a setup with a Windows 7 machine where we installed Dante Virtual Soundcard and start that soundcard with ASIO capabilities. The soundcard will receive audio over the network from a Tesira server. We want to capture the audio to files (highly preferring each channel to a separate file). The files will be played back on a later moment. There will likely be 6 channels or more.

  In the same setup we use ffmpeg to capture some video which is working fine, with Direct Show. So for audio we wanted to use the same setup, since ffmpeg is able to record audio as well. However, there seems to be no option to select the ASIO devices which the virtual soundcard probably creates. So the question is what command line to use for ffmpeg, or what to install ? Or which other program can record ASIO from command line ?

  I already tried installing :

  • Asio4all (actually wrong way around)
  • sox (don’t know why actually)
  • HiFi Cable Asio Bridge (from VB-audio, not enough channels even with donate version)
  • Voicemeeter (from VB-Audio, not enough channels and actually mixes down)
  • O Deus Asio link, this might be an interesting option but it did not let me configure any route, any suggestions ?

  One thing I noticed is that the virtual soundcard can also be set to use WDM. Then I can see the devices with ffmpeg -list_devices true -f dshow -i duymmy, but recording does not yield any result, I have to ctrl-c to make it stop instead of q, and the file is zero bytes. Supposedly this is because the data over the network is all ASIO formatted and the Tesira Server cannot send "WDM data". FFmpeg stops at selecting the capture pin for audio only

  EDIT :

  I ran ffmpeg with high verbosity and when selecting the WDM soundcard it stops at Selecting pin Capture on audio only. Also when requesting the options it gives the same line for 22 times : min ch=1 bits=8 rate= 11025 max ch=2 bits=16 rate= 44100