[Live-devel] Making ProxyServerMediaSubsession stream to multicast addresses

[Jan Ekholm]

On 19 maj 2014, at 23:50, Ross Finlayson <finlayson at live555.com> wrote:

>> Here I only try to get the original stream to work through the replicator. Based on the testReplicator example
>> all streams must be through a replicator, it's not possible to have one stream use the replicator and one
>> stream use the normal way.
> 
> That's correct.  Only one object can be reading from a "FramedSource".  (Otherwise, you'll see the "attempting to read more than once at the same time!" error message.)  That's the whole reason why I developed the "StreamReplicator" class: To make it possible for data from a "FramedSource" to be delivered  to more than one object.

It was a bit unclear that the StreamReplicator must be a central part of the source-filter-sink chain,
instead of just "hooking in" to some part.

However, as soon as I add the StreamReplicator the video starts to stutter. I leave it out, the stream
is fine. I don't actually do anything secondary yet, just trying to get the main stream working through
it. To me it looks like frames get rendered like: 1 2 3 4 5 3 4 5 6 7 5 6 7 8 ...  The stutter is not
consistent though and does not happen every time I test, but it's there. The stutter happens with:

    m_replicator = StreamReplicator::createNew( envir(), m_subsession->readSource(), False );
    H264VideoStreamDiscreteFramer * framer = H264VideoStreamDiscreteFramer::createNew( envir(), m_replicator->createStreamReplica() );
    if ( ! m_subsession->sink->startPlaying( *framer, ...  ) {

Simply changing that to:

    H264VideoStreamDiscreteFramer * framer = H264VideoStreamDiscreteFramer::createNew( envir(), m_subsession->readSource() );
    if ( ! m_subsession->sink->startPlaying( *framer, ...  ) {

to remove StreamReplicator from the equation and there is no stutter anymore. Switching where the replicator is like this:

    H264VideoStreamDiscreteFramer * framer = H264VideoStreamDiscreteFramer::createNew( envir(), m_subsession->readSource() );
    m_replicator = StreamReplicator::createNew( envir(), framer, False );
    if ( ! m_subsession->sink->startPlaying( *m_replicator->createStreamReplica(), ...  ) {

means no video is delivered at all anymore. So the replicator does something fishy, it's not a 1:1 pass through and
duplicator.

-- 
Jan Ekholm
jan.ekholm at d-pointer.com