cloud-chromioke

Chromecast Karaoke in the Cloud

How it works

This Dockerfile builds a pipeline that allows you to queue up and deliver Karaoke .cdg/.mp3 files to any Chromecast within your network. This requires installing this service into a publicly accessable cloud server such as DigitalOcean/EC2/Vultr/GCE and allowing this service access to your own digital .cdg/.mp3 audio/video collection so they can be processed on the fly and served onto any Chromecast device that supports movie playback.

The pipeline is as follows:

From S3 -> .zip file fetch -> unzipped -> frame_dumper applied to .cdg
-> ffmpeg applied to .png/.mp3 assets -> output.mp4 -> served via Go
server.

CDG frame_dumper

A rust application that concerns itself with taking a .cdg file and processing the bitmap data generating individual .png frames. This will generate on the order of a few thousand frames and these will be melded along with the original .mp3 file into a video file using ffmpeg in the next step.

FFmpeg

Data is processed as a directory of .png frames along with the original input.mp3. This means the ffmpeg command must combine this data into a format that is honored by the Chromecast.

fmpeg -r 25 -i tmpdir/frame_%05d.png -i input.mp3 
  -c:v libx264
  -profile:v high
  -level 5
  -crf 18
  -maxrate 10M
  -bufsize 16M
  -pix_fmt yuv420p
  -vf "scale=iw*sar:ih,scale='if(gt(iw,ih),min(1920,iw),-1)':'if(gt(iw,ih),-1,min(1080,ih))'"
  -x264opts bframes=3:cabac=1
  -movflags faststart
  -c:a aac
  -b:a 320k
  -y output.mp4

Notice the input is a temp directory with all the .png frames along with the input.mp3 file containing the audio.

The output is then a single file: `output.mp4' which is the final video file.

Where the address is that of your Chromecast which you can get from your Google Home app in the Settings section.

Building

docker build -t cdg .

Running the server (as a daemon)

docker run -d -v=`pwd`:/tmpdir -p 0.0.0.0:8080:8080 cdg

Processing a music file.

docker run -v=`pwd`:/tmpdir --entrypoint="./process.sh" cdg "{artist - song.zip}"

Casting

Casting is done with the Castnow node.js command-line tool as follows:

castnow --address 10.0.0.32 --type "video/mp4" output.mp4

This process is intended to be initiated within your LAN where you have network access to the internal ip of your Chromecast device.