Netstream - how to publish an mp3 file using RTMFP

Question

I want to publish a mp3 file from one of the peers and play it from other peers, very similiar to a RTMFP chat app.

From what I understand till now:

netstream.publish is used to publish a stream to RTMFP netconnection and netstream.play for playing a stream from other peers.
The steps for streaming mic and camera capture are:
netstream.attachCamera(cam);
netstream.attachAudio(mic);
netstream.publish('video');
However I don't see a way to publish (stream) mp3 files using Netstream. Note that using Netstream is essential since I want to "publish" audio to listening peers.

Please correct me if I was wrong above. Ideally what I want to achieve should be easily possible, yet I can't find any pointers for it. Is is possible to use ByteArray for the same. Any alternative streaming strategy would be welcome as long as it works with RTMFP. Links to code examples would be great too.

I dont think will be possible to do it using the publish of the NetStream. Another solution would be upload the mp3 using ByteArray, store this file in the server and then play it using a netstream on the listening peer. But it will have a big delay. — fmodos

Aralicia Aralicia · Accepted Answer · 2013-05-22T09:05:22

You stumbled upon one of the strange quirks of NetStream. It can publish sound from the microphone, but not from a arbitrary sound source. There is some workarounds, some more complex than the others.

Streaming through a virtual microphone. The easiest workaround, and the best (IMO) if your project allows you to use it. You just have to install a virtual microphone/camera software (ex : ManyCam) and use it to stream your mp3 file(s) through a virtual microphone. With that done, you just have to bind this microphone to your AS3 app. Sadly, it doesn't work for your project, since you can't reasonably ask of the publishing peer to install a virtual microphone.
Streaming usingSound.extract(), NetStream.send() and SampleDataEvent.SAMPLE_DATA. As you might know, NetStream.send() can be used to send messages to peers. The thing is, those messages are serialized and can be ByteArray. Thus, you can send audio data samples with NetStream.send(). The publishing pee apps can obtain the data samples with Sound.extract(), and the receiving apps can play them thanks to the SAMPLE_DATA event. One of the problems will be to know when you should send new samples. To manage that, you would recommend also using the SAMPLE_DATA in the publishing app and send new data each time the SAMPLE_DATA event occurs. The main issue with this method is that since you don't use the standard way of RTMP to stream audio, it needs a custom app for the receiver to play it. Given what you said of your project, it shouldn't be a problem.
Reproducing the RTMFP protocol using Socket. It would be long, very complex, and error-prone. I would never recommend to do this except perhaps as a learning experience. You would need to read, understand and implement most of the RTMFP Specification.

Netstream - how to publish an mp3 file using RTMFP

1 Answers