Re: timestamps on recorded events

[Takashi Iwai <tiwai@suse.de>]

Hi,

At Thu, 11 Apr 2002 10:42:05 +0100,
Richard Bown wrote:
> 
> Hi.  Another simple one but another one I'm afraid I can't find an example for.
> 
> I'm writing and reading events from the same ALSA 0.9.0 port (on the same
> duplex handle) - I receive the events correctly through snd_seq_event_input
> but the timestamps are coming back as zero even when I've started a queue
> against that handle.  I presume I don't have to extract the timestamps from
> the queue itself?

you can let the sequencer-core update the timestamp of the event
automatically.
at the subscription, call snd_seq_port_subscribe_set_time_update().

a typical code would be like this:

	snd_seq_addr_t sender, dest;
	snd_seq_port_subscribe_t *subs;
	snd_seq_port_subscribe_alloca(&subs);

	// receive events from a specified port
	sender.client = source_client_id;
	sender.port = source_port_id;	
	dest.client = my_client_id;
	dest.port = my_port_id;

	// set up subscribe info
	snd_seq_port_subscribe_set_sender(subs, &sender_addr);
	snd_seq_port_subscribe_set_dest(subs, &dest_addr);
	// set the queue to be used for updating time-stamps
	snd_seq_port_subscribe_set_queue(subs, queue_used);
	// enable time-stamp-update mode
	snd_seq_port_subscribe_set_time_update(subs, 1);
	// if you want to get real-time (not tick), call the
	// following, too
	// snd_seq_port_subscribe_set_time_real(subs, 1);

	err = snd_seq_port_subscribe(handle, subs);
	...

if you are using snd_seq_connect_to/from, then you need to replace
it like above.


Takashi