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• Reading avfoundation video device using FFMPEG library

  22 juin 2015, par Nipun

  I want to capture the screen on mac machine and dump into a file.

  ffmpeg -f avfoundation -i "1" -f mpeg1video screendump.mp4

  So I would like to achieve the same using programming in C/C++ using ffmpeg library.

  How do I receive the stream in a C/C++ program using FFMPEG library ?

  How do I write the received video into a file ?

• Problem with combining a video and an audio stream from USB device

  3 février 2020, par FHoevi

  I have two USB devices attached to an RPi, both show up as usual as /dev/video0. Here’s some additional info coming from two command line inputs :

  Device 1, video only (attached to an RPi4) :

  ffmpeg -f v4l2 -list_formats all -i /dev/video0 reports

  [video4linux2,v4l2 @ 0xe5e1c0] Compressed:       mjpeg :
  
  Motion-JPEG : 1280x720 640x480 320x240

  v4l2-ctl --list-formats-ext reports

  ioctl: VIDIOC_ENUM_FMT
  
          Type: Video Capture
  
          [0]: 'MJPG' (Motion-JPEG, compressed)
  
                  Size: Discrete 1280x720
  
                          Interval: Stepwise 0.033s - 0.033s with step 0.000s
  
  (30.000-30.000 fps)
  
                  Size: Discrete 640x480
  
                          Interval: Stepwise 0.033s - 0.033s with step 0.000s
  
  (30.000-30.000 fps)
  
                  Size: Discrete 320x240
  
                          Interval: Stepwise 0.033s - 0.033s with step 0.000s
  
  (30.000-30.000 fps)

  Does work : ffmpeg -f v4l2 -i /dev/video0 -vcodec h264_omx -preset ultrafast -tune zerolatency -g 300 -b:v 1M -mpegts_service_type advanced_codec_digital_hdtv -f mpegts udp://OtherMachine:Port?pkt_size=1316

  Device 2, video and audio (attached to an RPi3, but does not work either on the RPi4) :

  ffmpeg -f v4l2 -list_formats all -i /dev/video0 reports

  [video4linux2,v4l2 @ 0x2c41210] Compressed:       mjpeg :
  
  Motion-JPEG : 1920x1080 1280x720

  v4l2-ctl --list-formats-ext reports

  ioctl: VIDIOC_ENUM_FMT
  
                 Index       : 0
  
                 Type        : Video Capture
  
                 Pixel Format: 'MJPG' (compressed)
  
                 Name        : Motion-JPEG
  
                                Size: Discrete 1920x1080
  
                                              Interval: Discrete 0.033s
  
  (30.000 fps)
  
                                              Interval: Discrete 0.067s
  
  (15.000 fps)
  
                                Size: Discrete 1280x720
  
                                              Interval: Discrete 0.033s
  
  (30.000 fps)
  
                                              Interval: Discrete 0.067s
  
  (15.000 fps)

  After quite some tedious work and way too many hours I got this running :

  Video only : ffmpeg -f v4l2 -input_format mjpeg -i /dev/video0 -c:v copy -preset ultrafast -tune zerolatency -g 300 -f matroska udp://OtherMachine:Port?pkt_size=1316

  Does not work at all : ffmpeg -f v4l2 -input_format mjpeg -i /dev/video0 -c:v copy -preset ultrafast -tune zerolatency -g 300 -f mpegts udp://OtherMachine:Port?pkt_size=1316, on "OtherMachine" I do see that there is an incoming data stream via VLC, but it could not be digested properly.

  Audio only : ffmpeg -f alsa -thread_queue_size 1024 -i plughw:1 -c:a mp2 -ac 2 -ar 44100 -preset ultrafast -tune zerolatency -b:a 128K -f mpegts udp://OtherMachine:Port?pkt_size=1316

  But this does not work either :

  ffmpeg -f v4l2 -input_format mjpeg -i /dev/video0 -f alsa -thread_queue_size
1024 -i plughw:1 -c:v copy -c:a mp2 -ac 2 -ar 44100 -preset ultrafast -tune zerolatency -g 300  -b:a 128K -f mpegts udp://OtherMachine:Port?pkt_size=1316

  Could you please provide a hint on how to get these two streams for device 2 working together ? Both of them come from the same hardware/device, my guess is that the MJPG video stream is somehow not fully compliant with the mpegts standard (like it is for device 1) since it works with matroska, but not with mpegts. Could that be ? What needs to be done in that case ?

  Another hint, with the same kind of hardware setup I can do this

  cvlc -vvv v4l2:///dev/video0 --input-slave=alsa://plughw:1,0 --sout='#transcode{acodec=mpga,ab=128}:std{access=http,mux=asf,dst=:Port}'

  So, here my understanding is that video gets passed on unchanged (mjpeg) and audio gets transcoded via vlc’s mpga which presumably corresponds to mp2 for ffmpeg. The container format is asf, but I was not able to get that running with ffmpeg for no obvious reason. Anyway, picking up this vlc broadcast stream via http://StreamingMachine:Port on any other machine in my network is working well. But how to achieve that with ffmpeg directly and potentially not as http:// but udp :// or pipe stream ?

  Alternatively, let me ask this question : Given that I have an incoming mjpeg video stream as well as an incoming mp2 audio stream which kind of container format (ok, it’s obviously not mpegts) is the most appropriate one for combined streaming across my LAN or even into a pipe for further processing ? Believe me, I tried my very best over a couple of hours to find out how to proceed but with no success. At least to my humble knowledge there is nothing such like a table providing answers to questions of that kind.

  I’d be glad to get some insights.

  Best

• load rtmp provder if device is mobile

  1er mars 2015, par user3137017

  I’m using Apache, nginx, ffmpeg and phpvibe for a streaming website.

  I did make a demo on this page

  RTMP & HTTP

  So when the device is mobile, it will load the http provider, or else is the rtmp.

  I did put two different videos, but I can’t find the solution to integrate or modify the phpvibe’s code to do this

  This is the jwplayer’s code on phpvibe
  public function _jwplayer6 ($file,$thumb, $logo = null, $type=null)
  global $video ;

    $embed = '<div class="full">' . _lang("Loading the player...") . '</div>';
  
            $embed .= ' <code class="echappe-js">&lt;script type=&quot;text/javascript&quot;&gt;<br />
  
  <br />
  
      jwplayer(&quot;video-setup&quot;).setup({ primary : &quot;html5&quot;,  file: ***&quot;' . $file . '&quot;,***  image: &quot;' . $thumb . '&quot;, modes: [<br />
  
      { type: &quot;html5&quot; },<br />
  
      { type: &quot;flash&quot;, src: &quot;' . site_url() . 'lib/players/jwplayer/player.swf&quot; }<br />
  
  ], stretching: &quot;uniform&quot;,  height: ' . $this-&gt;height . ',   repeat: &quot;always&quot;,     width: &quot;100%&quot;';<br />
  
  &lt;/code&gt;&lt;/pre&gt;<br />
  
  <br />
  
  &lt;p&gt;I try to do this &lt;/p&gt;<br />
  
  <br />
  
  &lt;pre&gt;&lt;code&gt; $embed .= '&lt;script type=&quot;text/javascript&quot; src=&quot;//wurfl.io/wurfl.js&quot;&gt;&lt;/script&gt;
  &lt;script type=&quot;text/javascript&quot;&gt;<br />
  
                if(WURFL.is_mobile){<br />
  
                  var SourcesConteneuse = &quot;http'.substr($file,4).'&quot;;<br />
  
                }else{  <br />
  
                 var SourcesConteneuse = &quot;rtmp'.substr($file,4).'&quot;;<br />
  
                } <br />
  
          jwplayer(&quot;video-setup&quot;).setup({ primary : &quot;html5&quot;,  file : SourcesConteneuse , image : &quot;' . $thumb . '&quot;, modes: [<br />
  
          { type: &quot;html5&quot; },<br />
  
  &lt;/code&gt;&lt;/pre&gt;<br />
  
  <br />
  
  &lt;p&gt;but unfortunately jwplayer failed to load rtmp on desktops, but mobile load http&lt;/p&gt;<br />
  
  <br />
  
  &lt;p&gt;I checked the nginx and rtmp server and seems alright&lt;/p&gt;<br />
  
  <br />
  
  &lt;p&gt;So I need your help to find the correct code&lt;/p&gt;