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• How to overlay images sequence from pipe over a video stream with ffmpeg ?

  7 juin 2018, par Dotan Simha

  I’m trying to figure out an issue with ffmpeg.
  I have the following installation :
   DeckLink Mini Recorder Card (for HDMI input)
   DeckLink Mini Monitor Card (for HDMI output)

  I’ve successfully managed to take the HDMI input from the Decklink card and output is as-is to the output card with the following command :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I tried to add a complex-filter to add an overlay of an image, with the following command, and it works :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i ./tools/bin/windows/2.png -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I’m getting a realtime feed from the decklink recorder, the image is added to the stream, and it outputs it to the output HDMI card. Everything seems to work.

  Now I tried to change the static image path to use stdin (pipe:0), and I have a tool that constantly streaming PNG images to stdout :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i pipe:0 -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  The result that i’m getting on the output HDMI card is a static image, of the first frame.
  The output of ffmpeg also changes now, and it looks like it stuck of the first-second of the stream :

  ```
  frame= 30 fps=7.4 q=-0.0 size=N/A time=00:00:01.00 bitrate=N/A speed=0.247x

  frames : 30,
  currentFps : 7,
  currentKbps : NaN,
  targetSize : NaN,
  timemark : ’00:00:01.00’
  ```

  It just remains on 00:00:01.00 and never changes.

  I tried to find the issue, and did the following :

  • Tried to stream Decklink Recorder -> static png file overlay -> Decklink Monitor = IS WORKS

  • Tried to stream static png file -> Decklink Monitor = IS WORKS

  • Tried to stream pipe:0 (PNG files) -> Decklink Monitor = IS WORKS

  • Tried to stream Decklink Recorder -> pipe:0 (PNG files overlay) -> RAW AVI file IS WORKS

  The only issue is with :
   Tried to stream Decklink Recorder -> pipe:0 (PNG files) overlay -> Decklink Monitor DOES NOT WORK

  I suspect that Decklink output is more strict, and my pipe:0 with the PNG images is not stable, and the combination of both causes it to freeze.

  Any idea how to solve it ? :(

  Thanks !

• Concatenate chunk containg headers to another chunk in h264

  18 novembre 2014, par Ortixx

  I’m trying to extract thumbnails from a torrent stream by downloading the first couple of chunks to get the headers, another set of chunks from the middle and then concat them to have a single video file.

  For this I’m using nodejs but I’m having trouble with the concatenation part. Obviously the headers include the length of the video so if I simply concat another chunk to the end of the headers chunk, it won’t work.

  In other words, I have 2 chunks of a video file : The first one contains the headers and some material and the other one is fully composed of a video stream. I want to combine the two to form a single video file
  So my question is how can I make this work properly if at all ?

• Trying to compile last FFmpeg iPhone : error : invalid operand in inline asm

  1er décembre 2011, par juanramoney

  I am trying to compile last FFmpeg for iPhone, but I am getting an error :

      CC  libavformat/asfcrypt.o
  
  error: invalid operand in inline asm: 'ldr   ${0:Q}, $1  
  
      ldr   ${0:R}, $2  
  
      '
  
  make: *** [libavformat/asfcrypt.o] Error 1

  thanks