Audio recording: system exception: cannot lock mutex

[axolotl-logic]

I have an application where I read a video file with ofVideoPlayer (presumably AVFoundation), apply effects to it, and write each frame to ofxVideoRecorder. However, I'm having difficulty figuring out how exactly to pipe in the audio. I read the example source code, but that's getting it from a device and not from the videoplayer and I'm not sure how to bridge that gap.

Where I am currently is getting a segfault when I close and not recording any audio, despite my audio event handler being called. I'm doing the following:

recorder_.setVideoCodec("mjpeg");
recorder_.setVideoBitrate("2500k");
recorder_.setAudioCodec("mp3");
recorder_.setAudioBitrate("192k");
recorder_.setup("out-" + ofGetTimestampString() + ".mov", video_->getWidth(), video_->getHeight(), 60);
recorder_.start();

// int nOutputChannels, int nInputChannels, ofBaseApp *appPtr, int sampleRate, int bufferSize, int nBuffers
ofSoundStreamSetup(2, 0, this, 44100, 256, 4);

    void ofApp::audioReceived(float *input, int bufferSize, int nChannels){
        if (recording_) {
            recorder_.addAudioSamples(input, bufferSize, nChannels);
        }
    }

But receive the following error and a segfault:

[ fatal ] ofThreadErrorLogger::exception: System exception: cannot lock mutexits/s speed=1.04x
frame= 433 fps= 63 q=24.8 Lsize= 33543kB time=00:00:07.20 bitrate=38164.4kbits/s speed=1.05x
video:33541kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.008100%
Segmentation fault: 11

I assume there is something that I'm doing wrong. Any help would be appreciated.