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• ffmpeg concatenate clips with broken timecode

  19 septembre 2018, par Linus679

  I’ve just received some Blackmagic footage and some of the clips are separated into chunks because of dropped frames. So let’s say I have a set of clips that looks like below for a Clip 12.

  0100_C0012_001,
  0100_C0012_002,
  0100_C0012_003,

  Is there a way to create new clip from the 3 with the name 0100_C0012 ? Also, I have to actually concatenate the clips via timecode rather then the name as the numbers seems to break at points for some reason.

  Thanks for any help.

  The info about one of the clips is as follows :

    built with Apple LLVM version 9.1.0 (clang-902.0.39.2)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.0.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  
    libavutil      56. 14.100 / 56. 14.100
  
    libavcodec     58. 18.100 / 58. 18.100
  
    libavformat    58. 12.100 / 58. 12.100
  
    libavdevice    58.  3.100 / 58.  3.100
  
    libavfilter     7. 16.100 /  7. 16.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  1.100 /  5.  1.100
  
    libswresample   3.  1.100 /  3.  1.100
  
    libpostproc    55.  1.100 / 55.  1.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '///F_2_2018-07-06_1208_C0012_V1-0002.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      creation_time   : 2018-09-18T06:53:01.000000Z
  
      timecode        : 12:08:36:15
  
    Duration: 00:00:08.00, start: 0.000000, bitrate: 36177 kb/s
  
      Stream #0:0(eng): Video: dnxhd (DNXHD) (AVdn / 0x6E645641), yuv422p(pc, bt709), 1920x1080, 36175 kb/s, SAR 1:1 DAR 16:9, 24 fps, 24 tbr, 24k tbn, 24k tbc (default)
  
      Metadata:
  
        creation_time   : 2018-09-18T06:53:01.000000Z
  
        handler_name    : Apple Alias Data Handler
  
        encoder         : Avid DNxHD Codec
  
      Stream #0:1(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
  
      Metadata:
  
        creation_time   : 2018-09-18T06:53:02.000000Z
  
        handler_name    : Apple Alias Data Handler
  
        timecode        : 12:08:36:15
  
  At least one output file must be specified

• How to record a livestream in ffmpeg or gstreamer and split the files without skipping or duplicating frames

  15 décembre 2020, par Blake Cochrane

  Can somone please recommend a solution for safely recording a live stream to a file that would not produce a corrupted file if the system was unsavely shut down.

  


  I am starting on a project using a battery powered Raspberry Pi 4B.
I am using GStreamer to use the ASIC for Raw Pi camera to h.264 compression to create a RTSP/HLS/RTMP stream.
I need to continuosly record the livestream to a file on the Pi without any duplicate & missing frames or transcoding - eg using -vcodec copy.
As the Pi is battery powered, it can be unsafely shut down randomly when the battery is out of energy.
I know that if a mp4 container isn't 'finalised' with the moov atom before the file finishes writing which would leave the file corrupted/unrepairable and unplayable.
So if I have an mp4 recording of 6 hours that is corrupted and unfixable that is a problem.
My idea was to split the recording to a new file after x amount of minutes or frames or bytes as losing the last few minutes is not so bad as to lose hours of recordings.
I would need to set the last frame in the old file as the previous frame to the next I frame (starting frame) in the new file as a h.264 stream can only start on an I frame.

  


  So it would go like this.
file 1
| Frame |0001|I|
| --- | --- | --- |
|Frame|0002|P|
|Frame|0003|B|
...
| Frame |1524|B|
| --- | --- | --- |
| Frame |1525|P|

  


  file 2
| Frame |1526|I|
| --- | --- | --- |
| Frame |1527|B|

  


  Then all of the split files can be appended to each other without transcoding in ffmpeg.
I don't need to record the live stream directly to an mp4, whatever container it is in can be converted to an mp4 when appending the split files.

  


  There is a python script of the Raspberry pi that accomplishes all of this but it can not be used for a live stream multicast as the Pi camera can not be accessed by more than one process at a time.
Unless there is a way to live stream the latest frames in an mp4 file that is continiously being recorded to, I am stuck.

  


• FFmpeg recorded video is dark with Xvfb and chrome headless on Centos 7

  15 juin 2023, par narsy4

  I am trying to do a video recording of headless chrome session on Centos 7 (Amazon EC2 instance) using ffmpeg. I have installed ffmpeg, Xvfb and google chrome on the machine. I started Xvfb on :99, verified the display using xdpyinfo and started chrome. However when I run the ffmpeg cmd to capture the video (no errors in ffmpeg debug logs), the output is dark with a X sign in the centre of video screen. What am I doing wrong here ? Any help is appreciated.

  


  **Xvfb and chrome commands**
Xvfb :99 -screen 0 1920x1080x24 &
export DISPLAY=:99
google-chrome --headless --disable-gpu --no-sandbox --start-maximized --window-size=1920x1080 https://www.google.com



  


  **FFmpeg command**
ffmpeg -video_size 1920x1080 -framerate 30 -f x11grab -i :99 -loglevel debug -pix_fmt yuv420p /tmp/video.mp4



  


  dark video

  


  Searched for and read a few threads on this, but couldn't get it to work.