Is Qt capable of small-buffer low-latency video applications (e.g. live streaming)?

[rshe]

I am trying to create my own URL based live streaming application. I have hit an issue that the video streaming if having a delay of about 1000ms and there is no change in latency even after using LowLatency command. I want to achieve about 200ms latency video streaming.

( I want to genuinely know if Qt is the right tool for the job here, from people who know Qt and understand non-blocking, high priority, low latency programming. I already love Qt for its QML + JavaScript GUI building side.)

[koahnig]

@rshe said in Is Qt capable of small-buffer low-latency video applications (e.g. live streaming)?:

I am trying to create my own URL based live streaming application. I have hit an issue that the video streaming if having a delay of about 1000ms and there is no change in latency even after using LowLatency command. I want to achieve about 200ms latency video streaming.

Is this observation of 1 sec latency with Qt-based communication?

@rshe said in Is Qt capable of small-buffer low-latency video applications (e.g. live streaming)?:

( I want to genuinely know if Qt is the right tool for the job here, from people who know Qt and understand non-blocking, high priority, low latency programming. I already love Qt for its QML + JavaScript GUI building side.)

I am using TCP or UDP based data streaming and I cannot confirm your observation of long latencies. I expect to see more a latency of about 200ms. However, my streams are lower throughput in the kB/sec range, but they are larger number of streams in general.

This is merely a view from a user point, but I did not see reasons to doubts of Qt performances in that respect, yet. Latency is a critical factor in my applications.

[rshe]

@koahnig thanks for the reply. I am also using TCP or UDP based data streaming.
I have set the bit rate type to (VBR) varying bitrate type and it varies from say 800 – 8192 kb/S
below is my code. and I have also attached my camera settings.

#include "dialog.h"
#include <QApplication>

#include<QMediaPlayer>
#include<QVideoWidget>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    //Dialog w;
    //w.show();

    //QMediaPlayer::LowLatency = 0x01
    QMediaPlayer* player = new QMediaPlayer;

    QVideoWidget* vw = new QVideoWidget;

    player->setVideoOutput(vw);
    player->LowLatency;

    player->setMedia(QUrl("rtsp://admin:admin@192.168.253.99![/cam](image url)/realmonitor?channel=1&subtype=0&unicast=true"));

    vw->setGeometry(100,100,700,500);
    vw->show();

    player->play();
    return a.exec();
}

Can you please tell me is there anywhere I can improve to get low latency

[rshe]


[koahnig]

@rshe

Unfortunately, I have no experience with media/video player in Qt.

[rshe]

@koahnig Thanks for the reply.