title: GStreamer UDPSink blocksize property not working?
body: <p>I'm using GStreamer and sending audio using this pipeline:</p>
  
  <p><code>gst-launch-1.0 -v filesrc location=soundfile.mp3 ! mad ! audioconvert ! audio/x-raw, layout=interleaved, format=F32LE, channels=2 ! udpsink blocksize=512 port=5005 host=127.0.0.1</code></p>
  
  <p>However, <code>blocksize</code> doesn't appear to be working at all. This is the doc for udpsink, accessed by <code>gst-inspect udpsink</code>:</p>
  
  <pre><code>Element Properties:
    name                : The name of the object
                          flags: readable, writable
                          String. Default: "udpsink0"
    preroll-queue-len   : Number of buffers to queue during preroll
                          flags: readable, writable
                          Unsigned Integer. Range: 0 - 4294967295 Default: 0 
    sync                : Sync on the clock
                          flags: readable, writable
                          Boolean. Default: true
    max-lateness        : Maximum number of nanoseconds that a buffer can be late before it is dropped (-1 unlimited)
                          flags: readable, writable
                          Integer64. Range: -1 - 9223372036854775807 Default: -1 
    qos                 : Generate Quality-of-Service events upstream
                          flags: readable, writable
                          Boolean. Default: false
    async               : Go asynchronously to PAUSED
                          flags: readable, writable
                          Boolean. Default: true
    ts-offset           : Timestamp offset in nanoseconds
                          flags: readable, writable
                          Integer64. Range: -9223372036854775808 - 9223372036854775807 Default: 0 
    enable-last-buffer  : Enable the last-buffer property
                          flags: readable, writable
                          Boolean. Default: true
    last-buffer         : The last buffer received in the sink
                          flags: readable
                          MiniObject of type "GstBuffer"
    blocksize           : Size in bytes to pull per buffer (0 = default)
                          flags: readable, writable
                          Unsigned Integer. Range: 0 - 4294967295 Default: 4096 
    render-delay        : Additional render delay of the sink in nanoseconds
                          flags: readable, writable
                          Unsigned Integer64. Range: 0 - 18446744073709551615 Default: 0 
    throttle-time       : The time to keep between rendered buffers (unused)
                          flags: readable, writable
                          Unsigned Integer64. Range: 0 - 18446744073709551615 Default: 0 
    bytes-to-serve      : Number of bytes received to serve to clients
                          flags: readable
                          Unsigned Integer64. Range: 0 - 18446744073709551615 Default: 0 
    bytes-served        : Total number of bytes sent to all clients
                          flags: readable
                          Unsigned Integer64. Range: 0 - 18446744073709551615 Default: 0 
    sockfd              : Socket to use for UDP sending. (-1 == allocate)
                          flags: readable, writable
                          Integer. Range: -1 - 2147483647 Default: -1 
    closefd             : Close sockfd if passed as property on state change
                          flags: readable, writable
                          Boolean. Default: true
    sock                : Socket currently in use for UDP sending. (-1 == no socket)
                          flags: readable
                          Integer. Range: -1 - 2147483647 Default: -1 
    clients             : A comma separated list of host:port pairs with destinations
                          flags: readable, writable
                          String. Default: "localhost:4951"
    auto-multicast      : Automatically join/leave the multicast groups, FALSE means user has to do it himself
                          flags: readable, writable
                          Boolean. Default: true
    ttl                 : Used for setting the unicast TTL parameter
                          flags: readable, writable
                          Integer. Range: 0 - 255 Default: 64 
    ttl-mc              : Used for setting the multicast TTL parameter
                          flags: readable, writable
                          Integer. Range: 0 - 255 Default: 1 
    loop                : Used for setting the multicast loop parameter. TRUE = enable, FALSE = disable
                          flags: readable, writable
                          Boolean. Default: true
    qos-dscp            : Quality of Service, differentiated services code point (-1 default)
                          flags: readable, writable
                          Integer. Range: -1 - 63 Default: -1 
    send-duplicates     : When a distination/port pair is added multiple times, send packets multiple times as well
                          flags: readable, writable
                          Boolean. Default: true
    buffer-size         : Size of the kernel send buffer in bytes, 0=default
                          flags: readable, writable
                          Integer. Range: 0 - 2147483647 Default: 0 
    host                : The host/IP/Multicast group to send the packets to
                          flags: readable, writable
                          String. Default: "localhost"
    port                : The port to send the packets to
                          flags: readable, writable
                          Integer. Range: 0 - 65535 Default: 4951 
  </code></pre>
  
  <p>This is already somewhat confusing, as the default value for <code>blocksize</code> is listed as both 0 and 4096. It seems that it is 4096, however, as that is my UDP packet size no matter what value I use for <code>blocksize</code>. What's more confusing is that I can scarcely find any mention of the <code>blocksize</code> property anywhere online, even in GStreamer's own documentation: <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-good-plugins/html/gst-plugins-good-plugins-udpsink.html" rel="nofollow noreferrer">http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-good-plugins/html/gst-plugins-good-plugins-udpsink.html</a></p>
  
  <p>The only properties mentioned are <code>host</code> and <code>port</code>. Has <code>blocksize</code> been deprecated or something? And if so, is there any way to control the amount of data sent in each UDP packet? I've tried using the mtu property in RTP with no luck (see here: <a href="https://stackoverflow.com/questions/30982735/gstreamer-rtp-packet-size">gstreamer RTP packet size</a>) and am kind of at my wits' end with this.</p>