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• How can I improve the up-time of my coffee pot live stream ?

  26 avril 2017, par tww0003

  Some Background on the Project :

  Like most software developers I depend on coffee to keep me running, and so do my coworkers. I had an old iPhone sitting around, so I decided to pay homage to the first webcam and live stream my office coffee pot.

  The stream has become popular within my company, so I want to make sure it will stay online with as little effort possible on my part. As of right now, it will occasionally go down, and I have to manually get it up and running again.

  My Setup :

  I have nginx set up on a digital ocean server (my nginx.conf is shown below), and downloaded an rtmp streaming app for my iPhone.

  The phone is set to stream to example.com/live/stream and then I use an ffmpeg command to take that stream, strip the audio (the live stream is public and I don’t want coworkers to feel like they have to be careful about what they say), and then make it accessible at rtmp://example.com/live/coffee and example.com/hls/coffee.m3u8.

  Since I’m not too familiar with ffmpeg, I had to google around and find the appropriate command to strip the coffee stream of the audio and I found this :
  

  ffmpeg -i rtmp://localhost/live/stream -vcodec libx264 -vprofile baseline -acodec aac -strict -2 -f flv -an rtmp://localhost/live/coffee

  Essentially all I know about this command is that the input stream comes from, localhost/live/stream, it strips the audio with -an, and then it outputs to rtmp://localhost/live/coffee.

  I would assume that ffmpeg -i rtmp://localhost/live/stream -an rtmp://localhost/live/coffee would have the same effect, but the page I found the command on was dealing with ffmpeg, and nginx, so I figured the extra parameters were useful.

  What I’ve noticed with this command is that it will error out, taking the live stream down. I wrote a small bash script to rerun the command when it stops, but I don’t think this is the best solution.

  Here is the bash script :

  while true;
  
  do
  
          ffmpeg -i rtmp://localhost/live/stream -vcodec libx264 -vprofile baseline -acodec aac -strict -2 -f flv -an rtmp://localhost/live/coffee
  
          echo 'Something went wrong. Retrying...'
  
          sleep 1
  
  done

  I’m curious about 2 things :

  1. What is the best way to strip audio from an rtmp stream ?
  2. What is the proper configuration for nginx to ensure that my rtmp stream will stay up for as long as possible ?

  Since I have close to 0 experience with nginx, ffmpeg, and rtmp streaming any help, or tips would be appreciated.

  Here is my nginx.conf file :

  worker_processes  1;
  
  
  
  events {
  
      worker_connections  1024;
  
  }
  
  
  
  
  
  http {
  
      include       mime.types;
  
      default_type  application/octet-stream;
  
  
  
      sendfile        on;
  
  
  
      keepalive_timeout  65;
  
  
  
      server {
  
          listen       80;
  
          server_name  localhost;
  
  
  
          location / {
  
              root   html;
  
              index  index.html index.htm;
  
          }
  
  
  
          error_page   500 502 503 504  /50x.html;
  
          location = /50x.html {
  
              root   html;
  
          }
  
  
  
          location /stat {
  
                  rtmp_stat all;
  
                  rtmp_stat_stylesheet stat.xsl;
  
                  allow 127.0.0.1;
  
          }
  
          location /stat.xsl {
  
                  root html;
  
          }
  
          location /hls {
  
                  root /tmp;
  
                  add_header Cache-Control no-cache;
  
          }
  
          location /dash {
  
                  root /tmp;
  
                  add_header Cache-Control no-cache;
  
                  add_header Access-Control-Allow-Origin *;
  
          }
  
      }
  
  }
  
  
  
  rtmp {
  
  
  
      server {
  
  
  
          listen 1935;
  
          chunk_size 4000;
  
  
  
          application live {
  
              live on;
  
  
  
              hls on;
  
              hls_path /tmp/hls;
  
  
  
              dash on;
  
              dash_path /tmp/dash;
  
          }
  
      }
  
  }

  edit :
  I’m also running into this same issue : https://trac.ffmpeg.org/ticket/4401

• What are good settings for transcoding videos uploaded to my app ?

  14 mai 2020, par Dmitry Minkovsky

  I am working on an app that allows users to share videos. The problem is that many videos are very high bitrate. For example, A 4-minute H264 video from an old iPhone is encoded at 1080p and runs 17,000 kb/s ( 500 megabytes). Accepting and distributing such videos at this bitrate/resolution is not practical for a social application.

  



  I have been playing with ffmpeg to transcode videos to smaller sizes and higher compression, but have not achieved acceptable results. For example :

  



  ffmpeg \
    -i in.mov \
    -vf scale=w='if(gt(iw\,ih)\,780\,-2)':h='if(gt(iw\,ih)\,-2\,780)' \ 
    -c:v libx264 \
    -crf 28 \
    -preset medium \
    -pix_fmt yuv420p \
    -movflags +faststart \
    out.mp4


  



  This command transcodes the above-mentioned 500MB file down to 70MB. It scales the larger dimension of the video to 780 pixels and compresses the video quite a bit. The results are okay, but the file is still large.

  



  Taking the longer dimension down to 480 pixels, the file is reduced to 40MB. Still quite large, and now significantly degraded. Also, the transcoding still takes quite a long time : about 1-1.5x on my 4 year old i7 Macbook Pro with 16GB RAM.

  



  I'm not sure how to improve on this. H265 is not supported in browsers. I am wondering :

  



  

  • How can I reduce size further ?

  


  • How can I transcode faster than 1x without significantly reducing quality ? Even 2-3x doesn't seem great ?

  


  



  Is this as good as it gets ?

  


• corrupted HEIC tile when converting to JPEG

  27 mars 2018, par Kim Bowles Sørhus

  I’m having trouble converting a .HEIC image to a jpeg. The .HEIC file an image taken with an iphone running the latest ios public beta. I’m using the library nokia provided to parse the file and extract the image tiles from the .HEIC file, convert them to jpeg and glue them together using ffmpeg/montage.

  There is a bit too much code to paste it all into this question so i put all of it in this github repo. Its pretty self explanatory and should be runnable with just a few dependencies. They are explained in the repo’s README. This has all been done on osx btw.

  The .HEIC files contains a 8x6 grid of images(tiles) and if you put them together you get the complete image. Simply put whatever image i input the 7th tile is corrupted as shown below and i really don’t understand why. I’ve filed an issue with nokia, but the repo seems pretty dead and i don’t really expect an answer there.