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• Ffmpeg change aspect ratio setsar setdar owerriding

  20 novembre 2016, par Ngoral

  I’m trying to change the aspect ratio of video, cause it’s being showed in a wrong way (it sould be 16:9 but shows 3:4).
  I’ve tried a lot of things, and none worked.
  E.g. I’ve tried to set SAR, but it changes DAR, so the aspect ratio stays the same. Here’s an example :

  ffmpeg -y -i rtmp://localhost/in/air-hdmi -vf "setsar=sar=16/9" -f flv rtmp://localhost/in/ngoraltestffmpeg 
  
  
  
  
  
  
  
  [flv @ 0x38143c0] audio stream discovered after head already parsed
  
  [aac @ 0x3818f20] element type mismatch 1 != 0
  
  [flv @ 0x38143c0] video stream discovered after head already parsed
  
  Input #0, flv, from 'rtmp://localhost/in/air-hdmi':
  
    Metadata:
  
      Server          : NGINX RTMP (github.com/arut/nginx-rtmp-module)
  
      displayWidth    : 720
  
      displayHeight   : 576
  
      fps             : 0
  
      profile         : 
  
      level           : 
  
    Duration: 00:00:00.00, start: 181748.084000, bitrate: N/A
  
      Stream #0:0: Audio: aac (HE-AAC), 44100 Hz, stereo, fltp
  
      Stream #0:1: Video: h264 (High), yuv420p, 720x576, 25 fps, 25 tbr, 1k tbn, 50 tbc
  
  [flv @ 0x39bf5a0] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
  
      Last message repeated 1 times
  
  Output #0, flv, to 'rtmp://localhost/in/ngoraltest':
  
    Metadata:
  
      Server          : NGINX RTMP (github.com/arut/nginx-rtmp-module)
  
      displayWidth    : 720
  
      displayHeight   : 576
  
      fps             : 0
  
      profile         : 
  
      level           : 
  
      encoder         : Lavf57.38.101
  
      Stream #0:0: Video: flv1 (flv) ([2][0][0][0] / 0x0002), yuv420p, 720x576 [SAR 16:9 DAR 20:9], q=2-31, 200 kb/s, 25 fps, 1k tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc57.46.100 flv
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
  
      Stream #0:1: Audio: mp3 (libmp3lame) ([2][0][0][0] / 0x0002), 44100 Hz, stereo, fltp
  
      Metadata:
  
        encoder         : Lavc57.46.100 libmp3lame
  
  Stream mapping:
  
    Stream #0:1 -> #0:0 (h264 (native) -> flv1 (flv))
  
    Stream #0:0 -> #0:1 (aac (native) -> mp3 (libmp3lame))
  
  Press [q] to stop, [?] for help
  
  [aac @ 0x3a37000] element type mismatch 1 != 0
  
      Last message repeated 7 times
  
  [flv @ 0x39bf5a0] Failed to update header with correct duration.ate= 942.7kbits/s speed=2.37x    
  
  [flv @ 0x39bf5a0] Failed to update header with correct filesize.
  
  frame=  112 fps= 48 q=31.0 Lsize=     633kB time=00:00:05.18 bitrate= 999.9kbits/s speed=2.23x    
  
  video:546kB audio:82kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.846813%
  
  Exiting normally, received signal 2.

  I’ve also tried to apply scale=720:-1 and -aspect 16:9 and all left the same.

  BUT ! Wnen I write ffplay -vf setsar=16/9 rtmp://localhost/in/ngoraltest it shows perfectly what I need.
  What could be thae problem and hoe to solve it ?

  P.S. I’m little bit confused that there’s no onformation about SAR and DAR of input signal, but I can do totally nothing with it.

• Sync files timestamp with ffmpeg

  16 mars 2018, par Olivier Rivard

  I’m capturing video from 4 cameras connected with HDMI through a capture card. I’m using ffmpeg to save the video feed from the cameras to multiples jpeg files (30 jpeg per second per camera).

  I want to be able to save the images with the capture time. Currently I’m using this command for one camera :

  ffmpeg -f video4linux2 -pixel_format yuv420p -timestamps abs -I /dev/video0 -c:a jpeg -t 60 -ts_from_file 2 camera0-%5d.jpeg

  It saves my file with the names camera0-00001.jpg, camera0-00002.jpg, etc.

  Then I rename my file with camera0-HH-mm-ss-(1-30).jpeg based on the modified time of the file.

  So in the end I have 4 files with the same time and same frame like this :
  camera0-12-00-00-1.jpeg
  camera1-12-00-00-1.jpeg
  camera2-12-00-00-1.jpeg
  camera3-12-00-00-1.jpeg

  My issue is that the file may be offset from one to two frame. They may have the same name but sometime one or two camera may show different frame.

  Is there a way to be sure that the capture frames has the actual time of the capture and not the time of the creation of the file ?

• Create a video with audio only on one channel

  6 février 2018, par Jude Osborn

  I’m trying to create 5 videos that each play audio only in one channel. So, for example, one video only plays audio in the right front, another only in the back left, another only in the center, etc.

  The videos are currently stereo. Can I use ffmpeg to accomplish this ?