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• Output a video file from ffmpeg directly to google cloud storage

  24 juin 2021, par Anup Sedhain

  Background on the problem

  


  We are trying to compress a video using FFmpeg in our server that is hosted in the Google App Engine (GAE). The input file is in Google Cloud Storage (GCS) which can be easily passed as an input to FFmpeg and the processing is done, however, I wanted to output the file directly to GCS. I have referred to the documentation here https://ffmpeg.org/ffmpeg-protocols.html#http that they provided and used the correct headers and method to upload the file using a signed URL, but it doesn't seem to work. As of now, I am not even sure whether this is possible.

  


  Current Implementation

  


  Currently, we are first saving the output file in the GAE workspace and then uploading the file to the bucket. This flow worked fine until we faced another problem. Whenever the file is too big, the processing takes more than 10 mins which seems to be the threshold for Automatically Scaled Instances in the Flexible environment. To get around this problem we could use basic_scaling in a Standard environment but there we cannot seem to write files in the GAE workspace. I could choose to write in the /tmp directory but that uses RAM and we can have many files being uploaded at a time, so it's not an option.

  


  Possible Future

  


  Right now one solution I have seen is to use a Flexible environment with manual scaling, but this is a bad idea when it comes to scaling and cost-effectiveness. Another, which I am not so sure about would be to use Google Compute Engine but I am yet to try this.

  


  Conclusion

  


  The problem that arose from not being able to make a PUT request to Google Cloud Storage from FFmpeg led me to go through tens of problems surrounding GAE and its weird combination of instances and feature set.

  


  Would really appreciate suggestions or possible solutions if I am missing anything. If only we could make the FFmpeg output the file to GCS.

  


• sdp : Add an option for sending RTCP packets to the source of the last packets

  13 août 2013, par Martin Storsjö

  sdp : Add an option for sending RTCP packets to the source of the last packets
  An SDP description normally only contains the target IP address
  
  and port for the packets. This means that we don’t really have
  
  any clue where to send the RTCP RR packets - previously they’re
  
  sent to the destination IP written in the SDP (at the same port),
  
  which rarely is the actual peer. And if the source for the packets
  
  is on a different port than the destination, it’s never correct.
  With a new option, we can choose to send the packets to the
  
  address that the latest packet on each socket arrived from.
  
  — -
  
  Some may even argue that this should be the default - perhaps,
  
  but I’d rather keep it optional at first. Additionally, I’m not
  
  sure if sending RTCP RR directly back to the source is
  
  desireable for e.g. multicast.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavformat/rtsp.c
  • [DBH] libavformat/rtsp.h

• YUV420p to other formats, color shift problems

  1er juin 2013, par Sam

  So I'm writing a color detection application using an AR Drone. The drone sends my python/opencv socket server an image from its camera in YUV420p format.

  What I do to access the image as an opencv IPLImage is the following (and yes this is inefficient but I didn't / don't want to have to write new conversion tools myself) :

  1. Save the yuv image to a file (some_image.yuv)
  2. subprocess.call(insert ffmpeg call here)
  3. Read the resultant file (bmp, png, it doesn't matter) back in using cv.LoadImage

  My problem right now is a very noticable color shift. I'm waving a red felt sheet in these pictures. The first one shows a heavy yellow tint. The second isn't as bad but is very rare — mostly when I have the red sheet it's heavily tinted.

  • Tinted image : http://i.stack.imgur.com/BQikM.png
  • Less-tinted image : http://i.stack.imgur.com/ezHyy.png

  I'm wondering both of these things :

  1. if there's either a better way to do this
  2. If the color tinting issue can be resolved

  My ffmpeg conversion line looks something like

  ffmpeg -s 640x480 -vcodec rawvideo -f rawvideo -pix_fmt yuv420p -i image.yuv -vcodec bmp -f image2 output.bmp

  I've also tried :

  ffmpeg -f rawvideo -s 640x480 -pix_fmt yuv420p -vf colormatrix=bt709:bt601 -i image.yuv -f image -vcodec png output.png

  The color shift is always there, unfortunately !

  The color shift is my big problem right now as I later convert the image to HSV and use thresholding to choose a color range that works for me.