Issues with vlc.input.time not updating

JMGirard · Postby **JMGirard** » 02 Feb 2015 22:36

I am using ActiveX to embed VLC 2.1.5 within a MATLAB (R2014b) figure. While playing a video, I want to display the video time stamp multiple times per second using a timer. This all works quite nicely, except that the time stamp does not increment as fast as I'd like. If this were the case, the output would look like: 0.000, 0.100, ... , 2.000. Instead, it seems to repeat certain numbers (as shown below). Is this an issue of how I am querying the time stamp or does it just not update fast enough? Does the update speed vary by computer?

Code: Select all

fig = figure;
vlc = actxcontrol('VideoLAN.VLCPlugin.2',[0 0 400 300],fig);
t = timer(...
	'ExecutionMode','fixedRate', ...
	'Period',0.10, ...
    'TasksToExecute',20,...
	'TimerFcn','disp(vlc.input.time/1000);',...
    'StopFcn','vlc.playlist.stop()');
vlc.playlist.add('file://localhost/video.mp4');
vlc.playlist.play();
start(t);

Example Output:

Code: Select all

RSATom · Postby **RSATom** » 03 Feb 2015 08:38

It's old problem... http://stackoverflow.com/questions/1123 ... ate-result

JMGirard · Postby **JMGirard** » 03 Feb 2015 20:09

Thank you RSATom; the link was helpful. Ideally, VLC would increase its temporal resolution. However, in the meantime, I was able to adapt this work-around:

Code: Select all

function mwe
    last_ts_vlc = 0;
    last_ts_sys = 0;
    fig = figure;
    vlc = actxcontrol('VideoLAN.VLCPlugin.2',[0 0 400 300],fig);
    t = timer(...
        'ExecutionMode','fixedRate', ...
        'Period',0.05, ...
        'TasksToExecute',100,...
        'TimerFcn',@timer_Callback,...
        'StopFcn',@timer_Cleanup);
    vlc.playlist.add('file://localhost/video.mp4');
    a = tic;
    start(t);
    vlc.playlist.play();
    function timer_Callback(~,~)
        ts_vlc = vlc.input.time/1000;
        ts_sys = toc(a);
        if ts_vlc == last_ts_vlc && last_ts_vlc ~= 0
            ts_diff = ts_sys - last_ts_sys;
            ts_vlc = ts_vlc + ts_diff;
            fprintf('%f *\n',ts_vlc);
        else
            last_ts_vlc = ts_vlc;
            last_ts_sys = ts_sys;
            fprintf('%f\n',ts_vlc);
        end
    end
    function timer_Cleanup(~,~)
        delete(t);
    end
end

I now get output like this:

Code: Select all

0.000000
0.000000
0.379000
0.524026 *
0.547650 *
0.700000
0.796576 *
1.000000
1.036312 *
1.077174 *
1.215125 *
1.240523 *
1.300000
1.442218 *
1.450852 *
1.600000
1.748362 *
1.749543 *
1.820491 *
1.900000
2.200000
2.244058 *
2.500000
2.544737 *
2.687710 *
2.800000
2.817524 *
2.868725 *
3.100000
3.117315 *
3.161042 *
3.295879 *
3.400000
3.530405 *
3.555859 *
3.700000
4.000000
4.024536 *
4.072040 *
4.212366 *
4.300000
4.340622 *
4.363510 *
4.600000
4.701124 *
4.900000
4.948787 *
4.986760 *
5.019817 *
5.165957 *
5.200000
5.500000
5.800000
5.897894 *
5.923710 *
6.086371 *
6.100000
6.101379 *
6.400000
6.582067 *
6.700000
6.726970 *
6.785883 *
6.931990 *
7.000000
7.215887 *
7.300000
7.349231 *
7.535583 *
7.600000
7.795317 *
7.821314 *
7.900000
7.960549 *
8.200000
8.438918 *
8.500000
8.542604 *
8.688697 *
8.800000
8.849015 *
8.868693 *
8.912794 *
9.100000
9.400000
9.700000
9.709693 *
9.758806 *
10.000000
10.078359 *
10.100346 *
10.138720 *
10.300000
10.600000
10.619578 *

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Issues with vlc.input.time not updating

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