Question

I develop the first part of an Android application that allows to broadcast video stream through the network. Currently, I’m sending the video in a very direct way, like this:

Socket socket = new Socket(InetAddress.getByName(hostname), port);
ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(socket);
recorder.setOutputFile(pfd.getFileDescriptor());

But unfortunately, it is not very fluid. I want to buffered the data stream before sending it through the socket. One of the way I tried is to write the stream in a file using the Android API for recording media, and to use another thread to stream the file to the server on a conputer.

So my problem is: how can I send by a socket a file which is still under writing?
As BufferedInputStream has not a blocking method for reading, I tried to do things like this one, but without any success

while (inputStream.available() >= BUFFER_SIZE) {
  inputStream.read(buffer);
  outputStream.write(buffer);
}
outputStream.flush();

But when i’m doing that, if the network is faster than the datastream, I get quickly out of the loop.

Is there a ‘good’ way to do that? I though about doing active waiting but it is not a good solution, especially for mobiles. Another way is to do something like this :

while (true) {
  while (inputStream.available() < BUFFER_SIZE) {
    wait(TIME); 
  }
  inputStream.read(buffer);
  outputStream.write(buffer);
}
outputStream.flush();

But it sound quite dirty for me… Is there sleeker solution?

Answer 1

I can’t think of a pretty way of doing this, but one option might be to create a local socket pair, use the ‘client’ end of the pair as the MediaRecorder output fd, and buffer between the local-server socket and the remote-server. This way, you can block on the local-server until there is data.

Another possibility is to use a file-based pipe/fifo (so the disk doesn’t fill up), but I can’t remember if the Java layer exposes mkfifo functionality.

In any event, you probably want to look at FileReader, since reads on that should block.

Hope this helps,

Phil Lello