[Kdenlive-devel] current mlt jack issues

[Ed Rogalsky]

Hi Dan,

the last days I had some time and I worked on the jack integration in
kdenlive. Now I'm some steps farther.
But I have two issues:

*#1: MLT hangs on closing when filter_jackrack was active and
videoglwidget.cpp is compiled in kdenlive (opengl activated)*

It was tricky to find this problem but now its clear. When in Kdenlive
OPENGL is activated (see src/CMakeLists.txt)

if(OPENGL_FOUND)
  list(APPEND kdenlive_SRCS videoglwidget.cpp)
endif(OPENGL_FOUND)

then mlt (kdenlive) hangs forever on closing when the filter_jackrack was
loaded. If you shutdown the jackd before closing the
program it closes without hanging. If I compile kdenlive without
videoglwidget.cpp all is working just perfect. It seems that there are
some side effects between jackd/filter_jackrack and opengl.

*Any ideas what the problem is?*


*#2: funny sinus sound on transport stop when sdl_preview consumer is used
instead of sdl *

Steps to reproduce:

1) bash# MLT_CONSUMER=sdl_preview melt -jack my_sound.wav
2) start jack transport
3) stop jack transport

Now you can hear a pretty cool sinus tone or something like that with
different frequencies and volumes on every stop.

The reason for this is the code in consumer_sdl_preview.c:

static void *consumer_thread( void *arg )
{
...
        int *eos_threshold *= 20 + mlt_properties_get_int(
MLT_CONSUMER_PROPERTIES( this->play ), "buffer" );
        ...
// Loop until told not to
while( this->running )
{
// Get a frame from the attached producer
frame = mlt_consumer_get_frame( consumer );

// Ensure that we have a frame
if ( this->running && frame != NULL )
{
                        ....
// If we aren't playing normally, then use the still
if ( speed != 1 )
{
mlt_producer producer = MLT_PRODUCER( mlt_service_get_producer(
MLT_CONSUMER_SERVICE( consumer ) ) );
mlt_position duration = producer? mlt_producer_get_playtime( producer ) :
-1;
int pause = 0;

#ifndef SKIP_WAIT_EOS
if ( this->active == this->play )
{
// Do not interrupt the play consumer near the end
if ( *duration - this->last_position > eos_threshold* ) * <--- this
criteria is true on jack transport stop, why? *
{
// Get a new frame at the sought position
mlt_frame_close( frame );
if ( producer )
mlt_producer_seek( producer, this->last_position );
frame = mlt_consumer_get_frame( consumer );
pause = 1;
}
                                ...
}
#else
pause = this->active == this->play;
#endif
if ( *pause *) *<--- pause is true and the this->play (sdl) consumer is
stopped *
{
// Start the still consumer
*mlt_consumer_stop( this->play );*
this->last_speed = speed;
this->active = this->still;
this->ignore_change = 0;
mlt_consumer_start( this->still );
}
                                ...
}

The result is that in filter_jackrack.c:

the function *jackrack_get_audio*() is not called and the jack
"output_buffers" is not filled with data. Then in *jack_process*


static int *jack_process* (jack_nframes_t frames, void * data)
{
...
for ( i = 0; i < channels; i++ )
{
size_t jack_size = ( frames * sizeof(float) );
size_t ring_size;
 // Send audio through out port
jack_output_buffers[i] = jack_port_get_buffer( jack_output_ports[i], frames
);
if ( ! jack_output_buffers[i] )
{
mlt_log_error( MLT_FILTER_SERVICE(filter), "no buffer for output port
%d\n", i );
err = 1;
break;
}
* ring_size = jack_ringbuffer_read_space( output_buffers[i] );  <---
ring_size = 0, nothing is copied to jackd*
* jack_ringbuffer_read( output_buffers[i], ( char *
)jack_output_buffers[i], ring_size < jack_size ? ring_size : jack_size );*
....
}

the *ring_size *is 0 and no data is transfered to the jack outport
(*jack_output_buffers).
*In this case jackd produces a very painful sound (the mlt jack outports
are connected to system).
You get the same result if you set a breakpoint in the jack_process or the
consumer_thread.* *
*
*
The sdl consumer instead doesn't stop the generation of data and thats why
you don't get this behaviour for sdl (default consumer). But the SDL
Consumer doesn't work very well with video data.

Kdenlive uses the sdl_preview consumer for the monitors. Thats why I need a
solution for the sdl_preview consumer.

*Is there a solution for this (my) problem? *

Thanks
eddrog
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