A watermark can be applied to stream captured while translating it to subscribers. To do this, the following parameter should be added to flashphoner.properties file to specify watermark PNG file name:
custom_watermark_filename=watermark.png
Watermark PNG file should be placed to /usr/local/FlashphonerWebCallServer/conf catalog.
Watermark can be added only using the commercial license because Flashphoner watermark will be added to all streams when trial license is used.
Stream transcoding must be enabled to add watermark, because stream must be decoded and then encoded with picture applied for further broadcasting. To enable transcoding, the stream resolution can be set explicitly when publishing
session.createStream({name:'stream1',constraints:{audio:true,video:{width:640,height:480}}}).publish();
and playing the stream
session.createStream({name:'stream1',constraints:{audio:true,video:{width:320,height:240}}}).play();
In this case all the streams are publishing on server in 640x480 resolution and are playing in 320x240. That automatically enables transcoding, rescaling from 640x480 to 320x240 and watermark applying.
Stream watermarking will increase the server load approximately 0.5-1 core for each incoming video stream depending on video transcoded resolution. For example, 16 incoming streams handling may require 8-16 core server. In this regard, it is recommended to apply watermark on stream publisher source if possible.