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• stitching videos together using ffmpeg on the command line

  25 décembre 2015, par quinn

  Does anybody know how to stitch two (or more) videos together using ffmpeg (or another cli) ? This is assuming that all the videos are in the same format and the video format being used allows for lossless stitching (no transcode, just end-to-end stitching).

• Python/FFMPEG command line issues

  5 octobre 2011, par 12hys

  I have a problem with running an FFMPEG command from within a Python script. When I run the following command from the terminal, I can stream video and audio from my attached webcam (Logitech C310) and output to file "out.avi" without any errors.

  ffmpeg -f alsa -i default -itsoffset 00:00:00 -f video4linux2 -s 1280x720 -r 25 -i /dev/video0 out.avi

  When I run the same command in a Python script below,

  def call_command(command):
  
      subprocess.Popen(command.split(' '))
  
  
  
  call_command("ffmpeg -f alsa -i default -itsoffset 00:00:00 -f video4linux2 -s 1280x720 -r 25 -i /dev/video0 out.avi")

  it gives me the error :

  Input #0, alsa, from 'default':
  
    Duration: N/A, start: 1317762562.695397, bitrate: N/A
  
    Stream #0.0: Audio: pcm_s16le, 44100 Hz, 1 channels, s16, 705 kb/s
  
  [video4linux2 @ 0x165eb10]Cannot find a proper format for codec_id 0, pix_fmt -1.
  
  /dev/video0: Input/output error

  Could anyone shed some light on what could be going on here ? I've tried using os.system() as well as subprocess.call() and it gives me the same errors. I'm not sure where to start on what could be going wrong here. I tried searching for the "video4linux2 Cannot find a proper format for codec_id 0, pix_fmt -1" error, but couldn't find anything consistent.

  I've also tried putting the "ffmpeg -f..." command in a shell script "test.sh", and giving it executable permissions. I then open terminal, and run "./test.sh", and it works. When I try calling the command "./test.sh" from within my Python script, I'm left with the original error as before. This is the Python command I tried with the test.sh script :

  subprocess.call(["./test.sh"])

• Command-line streaming webcam with audio from Ubuntu server in WebM format

  28 avril 2017, par mjtb

  I am trying to stream video and audio from my webcam connected to my headless Ubuntu server (running Maverick 10.10). I want to be able to stream in WebM format (VP8 video + OGG). Bandwidth is limited, and so the stream must be below 1Mbps.

  I have tried using FFmpeg. I am able to record WebM video from the webcam with the following :

  ffmpeg -s 640x360 \
  
  -f video4linux2 -i /dev/video0 -isync -vcodec libvpx -vb 768000 -r 10 -vsync 1 \
  
  -f alsa -ac 1 -i hw:1,0 -acodec libvorbis -ab 32000 -ar 11025 \
  
  -f webm /var/www/telemed/test.webm 

  However despite experimenting with all manner of vsync and async options, I can either get out of sync audio, or Benny Hill style fast-forward video with matching fast audio. I have also been unable to get this actually working with ffserver (by replacing the test.webm path and filename with the relevant feed filename).

  The objective is to get a live, audio + video feed which is viewable in a modern browser, in a tight bandwidth, using only open-source components. (None of that MP3 format legal chaff)

  My questions are therefore :
  How would you go about streaming webm from a webcam via Linux with in-sync audio ? What software you use ?

  Have you succeeded in encoding webm from a webcam with in-sync audio via FFmpeg ? If so, what command did you issue ?

  Is it worth persevering with FFmpeg + FFserver, or are there other more suitable command-line tools around (e.g. VLC which doesn’t seem too well built for encoding) ?

  Is something like Gstreamer + flumotion configurable from the command line ? If so, where do I find command line documentation because flumotion doc is rather light on command line details ?

  Thanks in advance !