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• Gstreamer + Logitech C920 h264 video lacks timing information, plus mp4mux not working

  30 mars 2015, par user1048388

  I’m currently getting the h264 encoded video and the audio from the C920 via gstreamer 1.2.4 :

  gst-launch-1.0 v4l2src device=/dev/video0 do_timestamp=true ! video/x-h264,width=1920,height=1080,framerate=30/1 ! h264parse ! muxout. pulsesrc device="alsa_input.usb-046d_HD_Pro_Webcam_C920_5530335F-02-C920.analog-stereo" ! queue ! audioconvert ! voaacenc bitrate=65536 ! muxout. matroskamux name=muxout streamable=true ! queue ! filesink location=/home/[omitted]/test.mp4 

  The main problem is that the resulting video lacks timing information. By that I mean seek is not possible and the duration is unknown. Adding do_timestamp=true changes nothing.
  Simply copying the file in ffmpeg/libav shows several instances of :

  Non-monotonous DTS in output stream 0:0 ; previous : 926, current : 807 ; changing to 927. This may result in incorrect timestamps in the output file.

  After this short process (seconds on an hour long file), the timing information suddenly works for the entire video.

  What do I need to do to make this happen during the gst-launch pipeline ?

  There are some other problems which may or may not be related :
  I am using matroskamux despite wanting a mp4 container because mp4mux simply does not work in the given launch command. I receive

  ERROR : Pipeline doesn’t want to pause.
  ERROR : from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0 : Cannot identify device ’/dev/video0’.
  Additional debug info :
  v4l2_calls.c(568) : gst_v4l2_open () : /GstPipeline:pipeline0/GstV4l2Src:v4l2src0 :
  system error : No such file or directory

  when replacing matroskamux with mp4mux.

  I am clueless as to why this happens. Any help would be appreciated.

• ffmpeg and hardcoding subtitles

  8 avril 2015, par Adin Gill

  I have a command like so

  ffmpeg -i "F:\Filebotted\Rail Wars\Season 1\Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv" -map 0:0 -map 0:1 -b:v 750k -b:a 128k -c:v libx264 -c:a mp3 -ac 2 -filter_complex "subtitles=F:\Filebotted\Rail Wars\Season 1\Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv,scale=-1:360" "C:\Users\Adin\Desktop\Testy mc test\Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv"

  Yes it is long but unfortunatly ffmpeg chucks a hissy fit and spits out the following

  [subtitles @ 00000000050ce7c0] Unable to parse option value "FilebottedRail Wars
  
  Season 1Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv" as image size
  
      Last message repeated 1 times
  
  [subtitles @ 00000000050ce7c0] Error setting option original_size to value Fileb
  
  ottedRail WarsSeason 1Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv.
  
  [Parsed_subtitles_0 @ 0000000002c714c0] Error applying options to the filter.
  
  [AVFilterGraph @ 0000000002c5c540] Error initializing filter 'subtitles' with ar
  
  gs 'F:FilebottedRail WarsSeason 1Rail Wars.S01E07(7).You Look Good in That. 1080
  
  p.mkv'
  
  Error configuring filters.

  It works just fine when the file is in the same folder as ffmpeg (I found out that it doesn’t like ’ or - in the filename, but I just spent an hour trying to work out the issue with no avail.

  Any help will be appreciated :)

• FFMPEG Overlay 1080X1920 video over 1280X720 video at a particular vertical position

  9 mai 2019, par CRAIG

  I have a 1080X1920 (vertical) video with alpha channel with a blank spot 500px north of the bottom. This blank spot is 1080X607.

  I have a 1280X720 sized video I want to position in that spot, so the 1280 video will have to be sized down to 1080 wide and then positioned 500px from the bottom and UNDER the video on top.

  This is what I currently have, but it is failing beautifully.

  /usr/local/bin/ffmpeg  -i 1080x1920.mov -i 1280x720.MOV 
  
    -filter_complex "[1][0]overlay=main_w-overlay_w-0:main_h-overlay_h-500" 
  
    -c:v libx264 -profile:v high444 -pix_fmt yuv420p -level 3.1 -y  final.mp4