Recherche avancée

Sur d’autres sites (4549)

• Which H264 Level is supported by HTML5 on browsers ?

  17 mai 2017, par Koby Douek

  I’m trying to figure out which H264 Level is supported by HTML5 <video></video> elements in current browsers ?

  Current H264 Levels contraint of 1.0, 1.1.... all the way to 5.1

  For exmaple - in the following AS3 code, the following level is not supported by Google Chrome or IE :

  var h264Settings:H264VideoStreamSettings = new H264VideoStreamSettings();
  
  h264Settings.setProfileLevel( H264Profile.BASELINE, H264Level.LEVEL_3 );
  
                                                                  ▲ 

  Or setting the level in FFMPEG :

  -c:v libx264 -profile:v baseline -level 3.0

  Also does not work (in chrome).

  Which level value is supported by all current browsers ?

• How to detect two identical audio/video files with different volume level ?

  3 juillet 2017, par Marina Rappoport

  I’m working on program that could compare 2 video files and show difference.
  I compare audio track of files using SOX and FFMPEG :

  1. invert one of the files (sox)
  2. merge other file and invert version of first (sox)
  3. detect silence (ffmpeg)

  But if two file differs only by volume level - all audio track will be detected as non-silent ranges.

  How to understand that 2 files have the same audio track, but with different volume level ?

  I tried to change sound level via sox : sox -v 1.1 input.wav output.wav
  And then compare statistical information (-n stat).
  It works fine. Result of division parameters audio2/audio1 :

      Samples read 1.00;
  
      Length (seconds) 1.00;
  
      Scaled by 1.00;
  
      Maximum amplitude 1.10;
  
      Minimum amplitude 1.10;
  
      Midline amplitude 1.10;
  
      Mean norm 1.10;
  
      Mean amplitude 1.00;
  
      RMS amplitude 1.10;
  
      Maximum delta 1.10;
  
      Mean delta 1.10;
  
      RMS delta 1.10;
  
      Rough frequency 1.00;
  
      Volume adjustment 1/1.10;

  BUT ! When I tried ffmpeg to change volume of video : ffmpeg -i input.mp4 -vcodec copy -af "volume=10dB" output.mp4 (or volume=volume=0.5) and than compared sox audio statistic : I can’t find any patterns...

  Samples read    1.00
  
  Length (seconds)    1.00
  
  Scaled by   1.00
  
  Maximum amplitude   0.71
  
  Minimum amplitude   0.64
  
  Midline amplitude   -2401.73
  
  Mean    norm    0.34
  
  Mean    amplitude   0.50
  
  RMS     amplitude   0.36
  
  Maximum delta   0.37
  
  Mean    delta   0.34
  
  RMS     delta   0.36
  
  Rough   frequency   0.99
  
  Volume adjustment   0.71

  I will be grateful for any ideas and help.

• How to monitor volume level during ffmpeg capture

  7 septembre 2018, par Virkom

  I capture sound from soundcard, convert it to mp3 and stream to multicast IP.
  Command looks like :

  ffmpeg -f alsa -i hw:0 -async 1 -vn -acodec libmp3lame -ac 1 -ar 44100 -b:a 128k -flush_packets 0 -f mpegts -pes_payload_size 426 -mpegts_start_pid 0x44 udp://233.21.215.101:1234?pkt_size=1316

  But I need to monitor volume level of capturing. If there is no sound (or noise only) I need to switch to another (reserve) channel.

  Can I get volume level in ffmpeg output ? How I can do it ?

  P.S : I can get volume level by "volumedetect" filter but it’s not in realtime. I need realtime monitoring.

  P.P.S : I run ffmpeg programmatically from my application and can’t monitor additional windows (like video frame when I use showvolume filter).