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• How to record (and process ?) a video that is streamable from Android

  13 mai 2016, par afollestad

  My company’s app relies heavily on video recording and playback of web-based videos. I use the MediaRecorder API to record videos, through this library designed by me : https://github.com/afollestad/material-camera.

  For playback, I use this library which is basically a wrapper around Google’s ExoPlayer library : https://github.com/brianwernick/ExoMedia.

  It works fine for the most part with small videos, especially if I decrease bit rates for audio and video. However, larger and higher quality videos have many issues. Sometimes they seem to buffer forever, sometimes playback doesn’t even start successfully, etc. Again, these videos are being streamed over HTTP from Amazon S3.

  ---

  I’ve read a little bit about FFMPEG, and how it can process MP4’s for "faststart", splitting the files into chunks for DASH, etc. However, FFMPEG solutions for Android seem a bit complex, so...

  Is there anyway to record MP4’s from Android, with MediaRecorder, MediaCodec, or some other API which results in a video file that is fast to stream ? It amazes me how well Snapchat has figured this out.

• Need help understanding this script which uses ffmpeg to send rtmp input to node.js script

  4 juin 2022, par Arpit Shukla

  I was trying to understand this shell script which uses ffmpeg to take an rtmp input stream and send it to a node.js script. But I am having trouble understanding the syntax. Can someone please explain what is going on here ?

  


  The script :

  


  while :
do
  echo "Loop start"

  feed_time=$(ffprobe -v error -show_entries format=start_time -of default=noprint_wrappers=1:nokey=1 $RTMP_INPUT)
  printf "feed_time value: ${feed_time}"

  if [ ! -z "${feed_time}" ]
  then
  ffmpeg -i $RTMP_INPUT -tune zerolatency -muxdelay 0 -af "afftdn=nf=-20, highpass=f=200, lowpass=f=3000" -vn -sn -dn -f wav -ar 16000 -ac 1 - 2>/dev/null | node src/transcribe.js $feed_time

  else
  echo "FFprobe returned null as a feed time."
  
  fi

  echo "Loop finish"
  sleep 3
done


  


  

  • What is feed_time here ? What does it represent ?

  


  • What is this portion doing - 2>/dev/null | node src/transcribe.js $feed_time ?

  


  • What is the use of sleep 3 ? Does this mean that we are sending audio stream to node.js in chuncks of 3 seconds ?

  


  


• What's the best FFMPEG method for frequent, automated compilation of timelapse videos ?

  5 août 2020, par GoOutside

  I have a web application running on a not-particularly beefy Ubuntu Amazon Lightsail instance that uses FFMPEG to build a timelapse video generated from downloaded .jpg webcam photos taken every 2 minutes throughout the day (720 total images each day, which grows throughout the day as new images are downloaded).

  


  The code I'm running every 20 minutes is this :

  


  ffmpeg -y -r 24 -pattern_type glob -I 'picturefolder/*.jpg' -s 1024x576 -vcodec libx264 picturefolder/timelapse.mp4

  


  This mostly works, but it is often quite slow, taking 30-60 seconds to run and getting slower as the day goes on, of course.

  


  Recently, I tried to use concat instead of globbing the entire folder over and over. I did not see a noticeable performance improvement, ass it appears the concat processes the entire video in order to add even just a few frames to the end of it.

  


  My question for any FFMPEG experts out there : what is the most efficient way to handle this kind of automated timelapse creation, given my setup ? Is there a flag I'm missing ? Perhaps a different, more efficient method ? Or maybe a way to have the FFMPEG process just crawl through this at a more 'slow and steady' pace instead of big bursts of CPU usage.

  


  Or am I stuck with this and should just deal with it ? My ultimate goal would be to continue using my current tier (2 GB RAM, 1 vCPU) without the expense of upgrading. Thank you very kindly for your help !