Function process_callback

libavdevice/jack.c:60–115

} JackData;

static int process_callback(jack_nframes_t nframes, void *arg)
{
    /* Warning: this function runs in realtime. One mustn't allocate memory here
     * or do any other thing that could block. */

    int i, j;
    JackData *self = arg;
    float * buffer;
    jack_nframes_t latency, cycle_delay;
    AVPacket pkt;
    float *pkt_data;
    double cycle_time;

    if (!self->client)
        return 0;

    /* The approximate delay since the hardware interrupt as a number of frames */
    cycle_delay = jack_frames_since_cycle_start(self->client);

    /* Retrieve filtered cycle time */
    cycle_time = ff_timefilter_update(self->timefilter,
                                      av_gettime() / 1000000.0 - (double) cycle_delay / self->sample_rate,
                                      self->buffer_size);

    /* Check if an empty packet is available, and if there's enough space to send it back once filled */
    if (!av_fifo_can_read(self->new_pkts) ||
        !av_fifo_can_write(self->filled_pkts)) {
        self->pkt_xrun = 1;
        return 0;
    }

    /* Retrieve empty (but allocated) packet */
    av_fifo_read(self->new_pkts, &pkt, 1);

    pkt_data  = (float *) pkt.data;
    latency   = 0;

    /* Copy and interleave audio data from the JACK buffer into the packet */
    for (i = 0; i < self->nports; i++) {
        jack_latency_range_t range;
        jack_port_get_latency_range(self->ports[i], JackCaptureLatency, &range);
        latency += range.max;
        buffer = jack_port_get_buffer(self->ports[i], self->buffer_size);
        for (j = 0; j < self->buffer_size; j++)
            pkt_data[j * self->nports + i] = buffer[j];
    }

    /* Timestamp the packet with the cycle start time minus the average latency */
    pkt.pts = (cycle_time - (double) latency / (self->nports * self->sample_rate)) * 1000000.0;

    /* Send the now filled packet back, and increase packet counter */
    av_fifo_write(self->filled_pkts, &pkt, 1);
    sem_post(&self->packet_count);

    return 0;
}

static void shutdown_callback(void *arg)