> How can I get access to pixel data (for reading) when being presented a
> frame? I have the following:
>
> class VideoSurface: public QAbstractVideoSurface {
> bool present(const QVideoFrame &frame) override {
> // I can't map() because frame is const and map() is not marked const
> // and frame is not already mapped, so what can I do with it?
> }
> };
Having played with this further, I think something i wrong with Qt. I can't
map() the frame even if I clone it (as found in various places on the web):
bool present(const QVideoFrame &frame) override {
QVideoFrame frame2(frame);
frame2.map(QAbstractVideoBuffer::ReadOnly); // this fails!
...
}
Even when I comment out all the frame logic except for a qDebug() and return
true, there seems to be only one frame ever presented:
auto main(int, char **)::(anonymous
class)::operator()(QMediaPlayer::MediaStatus) const QMediaPlayer::LoadingMedia
auto main(int, char **)::(anonymous class)::operator()(const
QMediaPlayer::State &) const QMediaPlayer::PlayingState
auto main(int, char **)::(anonymous
class)::operator()(QMediaPlayer::MediaStatus) const QMediaPlayer::BufferedMedia
virtual bool VideoSurface::start(const QVideoSurfaceFormat &)
virtual bool VideoSurface::present(const QVideoFrame &) 0 true (frameNumber,
frame.iValid())
... 23 seconds later...
auto main(int, char **)::(anonymous
class)::operator()(QMediaPlayer::MediaStatus) const QMediaPlayer::EndOfMedia
virtual void VideoSurface::stop()
auto main(int, char **)::(anonymous class)::operator()(const
QMediaPlayer::State &) const QMediaPlayer::StoppedState
The video is an MP4 file from disk, 23 seconds long 71MB, I should have ~690
present() invocations.
Any help is appreciated!
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