SoX running slow using a ProcessBuilder

Question

I am running SoX using using a ProcessBuilder in java that trims WAV files into 30 second long WAV files.

SoX is running because I can get the first 30 seconds of the file successfully trimmed and saved as a new file but it stops there however, it's still running.

This is the code for the command generation:

command.add (soxCommand);
    if (SoxWrapper.getMetadata (srcFile, MetadataField.SAMPLE_RATE) != 16000) {
        command.add ("-V3");
        command.add ("-G");
        command.add (FilenameUtils.normalize (srcFile.getAbsolutePath ()));
        command.add ("-b 16");
        command.add (FilenameUtils.normalize (destFile.getAbsolutePath ()));
        command.add ("channels");
        command.add ("1");
        command.add ("rate");
        command.add ("16000");
        command.add ("trim");
        command.add (startTime.toString ());
        command.add ('=' + endTime.toString ());
    } else {
        command.add ("-V3");
        command.add (FilenameUtils.normalize (srcFile.getAbsolutePath ()));
        command.add ("-b 16");
        command.add (FilenameUtils.normalize (destFile.getAbsolutePath ()));
        command.add ("trim");
        command.add (startTime.toString ());
        command.add ('=' + endTime.toString ());
    }

This is the code for the process creation:

    private static Process createProcess (List<String> command) {

    ProcessBuilder soxProcessBuilder = new ProcessBuilder (command);
    soxProcessBuilder.redirectErrorStream (true);

    Process soxProcess = null;
    try {
        soxProcess = soxProcessBuilder.start ();

        int soxreturn = soxProcess.waitFor ();
        soxLogger.info ("SoX returned: " + soxreturn);

    } catch (IOException t) {
        logger.error ("SoX Process failed", t);
    } catch (InterruptedException e) {
        logger.error ("Failed to wait for SoX to finish", e);
    }

    return soxProcess;
}

Nathan Hughes · Answer 1 · 2011-08-12T16:33:15.957

It's blocked because it's writing stuff to stdout, the buffer has filled up so the process is waiting until the buffer makes space for it, but your program isn't reading it so the buffer stays full. Since you redirected stderr to stdout it's possible some kind of error cropped up and you don't know about it because you're not reading from the stream. You need to read from the process's getInputStream, something like:

new Thread(new Runnable() {
    @Override public void run() {
        try {
            org.apache.commons.io.IOUtils.copy(soxProcess.getInputStream(), System.out);
        } catch (IOException e) {
            e.printStackTrace(System.err);
        }
    }    
}).start();

(Here you'd need to make soxProcess final so the inner class method can see it.)

Alternatively with the new JDK you now have the alternative of having the processBuilder redirect the output to a file.

SoX running slow using a ProcessBuilder

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