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I am using janus-gateway for recording in web-browser. Once the recording is completed, two files are generated, one is audio and another is a video. Both have format mjr. How can I combine both these files to create a single file?

mpromonet
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Anuj
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3 Answers3

7

I was dealing with the same need.

If you did the default janus-gateway install you only miss these steps:

run this on the folder where you downloaded the git sources:

./configure --enable-post-processing

then

make
(sudo) make install

then run this for each file you want to convert them to audio/video formats:

./janus-pp-rec /opt/janus/share/janus/recordings/video.mjr /opt/janus/share/janus/recordings/video.webm

./janus-pp-rec /opt/janus/share/janus/recordings/audio.mjr /opt/janus/share/janus/recordings/audio.opus

if you don't have ffmpeg installed run this (i'm on Ubuntu, on other distros ffmpeg might be already in apt-get repositories)

sudo add-apt-repository ppa:kirillshkrogalev/ffmpeg-next
sudo apt-get update
sudo apt-get install ffmpeg

and then finally to merge audio with video:

(sudo) ffmpeg -i audio.opus -i video.webm  -c:v copy -c:a opus -strict experimental mergedoutput.webm

from there you can build a shell script to convert all mjr files automatically on a cron

Macumbaomuerte
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I have a very primitive example of doing this in C with Gstreamer. Note, this code is very messy but it should show you what you need to do.

Here is a list of what needs to be done to merge these files:

  1. Build the list of RTP buffers so that you can iterate over them in the file. There are examples of this in the janus-gateway post processing
  2. Start iterating over your files at the same time. The timestamps should sync up OK, though I have run into issues where a packet would be lost or corrupted on write which will screw up the merge
  3. I decode the media and re-encode it here so that I can statically set the framerate and size for the video. I am sure that there is a way to do this without having to transcode the media.
  4. Multiplex and write to a file

I do step 1 exactly like the janus post processer. Step 2 I push each rtp packet from the files to a gstreamer appsrc element. Steps 3 and 4 are done within the gstreamer pipelines.

Benjamin Trent
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sudo apt-get install libavutil-dev libavcodec-dev libavformat-dev

After Installing Dependencies...

./configure --prefix=/opt/janus --enable-post-processing

Then Use this BASH file

#!/bin/bash

# converter.sh

# Declare the binary path of the converter
januspprec_binary=/opt/janus/bin/janus-pp-rec

# Contains the prefix of the recording session of janus e.g
session_prefix="$1"
output_file="$2"

# Create temporary files that will store the individual tracks (audio and video)
tmp_video=/tmp/mjr-$RANDOM.webm
tmp_audio=/tmp/mjr-$RANDOM.opus

echo "Converting mjr files to individual tracks ..."
$januspprec_binary $session_prefix-video.mjr $tmp_video
$januspprec_binary $session_prefix-audio.mjr $tmp_audio

echo "Merging audio track with video ..."

ffmpeg -i $tmp_audio -i $tmp_video  -c:v copy -c:a opus -strict experimental $output_file

echo "Done !"

The following command should do the trick:

bash converter.sh ./room-1234-user-0001 ./output_merged_video.webm
Vinay Vadachhak
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