CODEWITHSUNDEEP
c++audiostreamingmp3audio-streaming
Pedro Borges
Pedro Borges

Reputation: 1260

How to obtain mp3 audio packets for streaming in C/C++

I want to be able to break a song into packets and have access to these individual packets. The reason for that is that I want to send each individual packet over the network using an experimental network protocol called Named Data Network.

As the packets arrive at the destination I want to play them. So I want to implement a streaming functionality. The only difference is the network layer that I will use. This network layer is not based on IP.

Does anyone know any C/C++ implementation of breaking a song file into pieces and then playing these packets individually? I looked over Gstreamer, but it seems complicated to get individual packets from its pipeline structure. I found this reference which was the closest to what I wanted, however it was not so clear for me: how can I parse audio raw data recorder with gstreamer?

Summarizing the points I need:

  1. Break a song into packets
  2. Play the audio content of a single packet (or a small set of packets).

Thank you very much for the help!

Upvotes: 4

Views: 3786

Answers (1)

Gilles Gregoire
Gilles Gregoire

Reputation: 1756

An MP3 file is just a succession of MP3 frames. Each frame is made of a header and a data block.

Splitting the MP3 file as MP3 frames will involve parsing the MP3 file. You can refer to this documentation for a good description of the format.

Note that in the case of mpeg layer 3 codec, frames are not independant. In the worst case, 9 input frames may be needed before beeing able to decode one single frame.

What I would do instead of this

I guess you could probably ignore most of these details and focus on the streaming problem itself. Here is what I would try to build first:

  • on the sender side, split a file into packets, and send them one by one using your system. Command example: send_stream test.mp3

  • on the receiver side, receive the packets and rebuild the original file. Command example: receive_stream test.mp3

Once you have this working fine, modify the receiver program so that it writes the packets in-order on the standard output. This will allow you to redirect stdout to a file

# sender side did not change
send_stream test.mp3

# receiver side
receive_stream > test.mp3

Then, you can use madplay to play the mp3 while it is received simply by redirecting receive_stream output to madplay:

# madplay - tells madplay to read its input from standard input.
receive_stream | madplay -

For a good mp3 decoder, take a look at MAD.

Upvotes: 3

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