Events sent by external clients subscribed to the input port are not timestamped.
This inconsistent behavior may surprise newbies who look at seq-decoder as a reference example.
See the example below using "vkeybd --addr 128:0" to connect to seq-decoder, the events sent by vkeybd are on a different queue with no timestamps:
... EVENT>>> Type = 66, flags = 0x0, time = 0 ticks Source = 0.1, dest = 128.0, queue = 253 Event = Port Subscribed; 129:0 -> 128:0 EVENT>>> Type = 66, flags = 0x1, time = 4.829712627 Source = 0.1, dest = 128.0, queue = 0 Event = Port Subscribed; 129:0 -> 128:0 EVENT>>> Type = 10, flags = 0x0, time = 0 ticks Source = 129.0, dest = 128.0, queue = 253 Event = Controller; ch=0, param=0, value=0 EVENT>>> Type = 11, flags = 0x0, time = 0 ticks Source = 129.0, dest = 128.0, queue = 253 Event = Program Change; ch=0, program=0 ...
After the change events are on the main queue and are timestamped:
... EVENT>>> Type = 66, flags = 0x1, time = 4.280907223 Source = 0.1, dest = 128.0, queue = 0 Event = Port Subscribed; 129:0 -> 128:0 EVENT>>> Type = 66, flags = 0x1, time = 4.280912063 Source = 0.1, dest = 128.0, queue = 0 Event = Port Subscribed; 129:0 -> 128:0 EVENT>>> Type = 10, flags = 0x1, time = 4.280990702 Source = 129.0, dest = 128.0, queue = 0 Event = Controller; ch=0, param=0, value=0 EVENT>>> Type = 11, flags = 0x1, time = 4.280994862 Source = 129.0, dest = 128.0, queue = 0 Event = Program Change; ch=0, program=0 ...
Signed-off-by: Antonio Ospite ao2@ao2.it ---
Hi,
while looking into improving the alsamidisrc[1,2] GStreamer element, I took a better look at what the sequencer API could do and started using test/seq-decoder.c as a reference example.
I noticed the issue discussed above and I tried to fix it in order to have a more consistent behavior of event timestamping.
I think the new behavior is less surprising for newbies but I may still be missing something, please let me know if I am.
Thanks, Antonio
[1] https://cgit.freedesktop.org/gstreamer/gst-plugins-base/tree/ext/alsa/gstals... [2] https://bugzilla.gnome.org/show_bug.cgi?id=787683
test/seq-decoder.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/test/seq-decoder.c b/test/seq-decoder.c index b110e98d..38755553 100644 --- a/test/seq-decoder.c +++ b/test/seq-decoder.c @@ -283,6 +283,12 @@ void event_decoder(snd_seq_t *handle, int argc, char *argv[]) snd_seq_port_info_set_name(pinfo, "Input"); snd_seq_port_info_set_type(pinfo, SND_SEQ_PORT_TYPE_MIDI_GENERIC); snd_seq_port_info_set_capability(pinfo, SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_WRITE); + + /* Enable timestamping for events sent by external subscribers. */ + snd_seq_port_info_set_timestamping(pinfo, 1); + snd_seq_port_info_set_timestamp_real(pinfo, 1); + snd_seq_port_info_set_timestamp_queue(pinfo, queue); + if ((err = snd_seq_create_port(handle, pinfo)) < 0) { fprintf(stderr, "Cannot create input port: %s\n", snd_strerror(err)); return;