[Interest] (code) Cannot map videoforames for QAbstractVideoSurface::present
Jason H
jhihn at gmx.com
Mon Jun 18 13:12:41 CEST 2018
Truely excellent. Thanks so much. There was no thing that elluded to this in the docs. And I don't know very much about GL. Thanks!
> Sent: Monday, June 18, 2018 at 1:29 AM
> From: "Gil H" <qt at tastytech.ca>
> To: "Qt Interest" <interest at qt-project.org>
> Subject: Re: [Interest] (code) Cannot map videoforames for QAbstractVideoSurface::present
>
> Hi Jason, you need to check the handle type on the QVideoFrame. If input->handleType() == QAbstractVideoBuffer::NoHandle then you can map the memory directly, as you've tried. But on Mac, the handle type is GLTextureHandle and you need to write some OpenGL code to get the texture handle, read it, and then get at the pixels that way.
>
> Here's a bit of code I used to do this:
>
> // declare as class members
> QByteArray _frameBuffer;
> int _frameBytes;
> GLuint _fbo;
>
> // in processing function:
> GLuint textureId = input->handle().toUInt();
> if (_fbo == 0)
> glGenFramebuffers(1, &_fbo);
>
> _frameBytes = input->width()*input->height() * 4;
>
> GLuint prevFbo;
> glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint *) &prevFbo);
> glBindFramebuffer(GL_FRAMEBUFFER, _fbo);
> glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureId, 0);
>
> #ifdef Q_OS_IOS
> glReadPixels(0, 0, input->width(), input->height(), GL_RGBA, GL_UNSIGNED_BYTE, _frameBuffer.data());
> #else
> glReadPixels(0, 0, input->width(), input->height(), GL_BGRA_EXT, GL_UNSIGNED_BYTE, _frameBuffer.data());
> #endif
>
> glBindFramebuffer(GL_FRAMEBUFFER, prevFbo);
>
> // at this point _frameBuffer bytearray contains your pixels
>
>
> Hope this saves you some of the headaches I went through as well!
>
> Gil
>
>
> On 6/14/18, 11:26 AM, "Interest on behalf of Jason H" <interest-bounces+qt=tastytech.ca at qt-project.org on behalf of jhihn at gmx.com> wrote:
>
> Yes, I essentially have that (your message just made it to my email after I sent my code)
> I don't know why map() would fail, and why bits() would not be valid.
>
> I'm on OSX, reading from an MP4...
>
>
> > Sent: Thursday, June 14, 2018 at 7:12 AM
> > From: "Igor Mironchik" <igor.mironchik at gmail.com>
> > To: interest at qt-project.org
> > Subject: Re: [Interest] (code) Cannot map videoforames for QAbstractVideoSurface::present
> >
> > Hi,
> >
> > Start from here:
> >
> > bool
> > Frames::present( const QVideoFrame & frame )
> > {
> > if( !isActive() )
> > return false;
> >
> > QVideoFrame f = frame;
> > f.map( QAbstractVideoBuffer::ReadOnly );
> >
> > QImage image( f.bits(), f.width(), f.height(), f.bytesPerLine(),
> > QVideoFrame::imageFormatFromPixelFormat( f.pixelFormat() ) );
> >
> > f.unmap();
> >
> > emit newFrame( image.copy( image.rect() ) );
> >
> > return true;
> > }
> >
> > This works for me...
> >
> >
> > 14-Jun-18 17:52, Jason H пишет:
> > > I have no idea what I'm doing wrong. Can someone this and let me know?
> > > The frames I'm getting are BGR32, so I have special code for that.
> > > But I'm getting the message "QVideoFrame::unmap() was called more times then QVideoFrame::map()"
> > > Which is obviously not the case.
> > >
> > > To restate the problems:
> > > 1. I only get to present() once
> > > 2. I's failing to map frames
> > > 3. "then" in the message should be "than"
> > >
> > > Here's the first 3 lines of the .pro and complete code:
> > > extractframes.pro-----
> > > QT += multimedia
> > > CONFIG += c++11 console
> > > CONFIG -= app_bundle
> > >
> > > main.cpp--------------
> > > #include <QAbstractVideoSurface>
> > > #include <QGuiApplication>
> > > #include <QMediaPlayer>
> > > #include <QVideoSurfaceFormat>
> > >
> > > #include <QtDebug>
> > >
> > > class VideoSurface: public QAbstractVideoSurface {
> > > int _frameNumber;
> > > QVideoSurfaceFormat _format;
> > > QString _prefix;
> > > int _frameInterval;
> > > public:
> > > VideoSurface(const QString &prefix, int frameInterval): _prefix(prefix), _frameInterval(frameInterval) { }
> > >
> > > bool present(const QVideoFrame &frame) override {
> > > qDebug() << Q_FUNC_INFO << _frameNumber << frame.isValid();
> > >
> > > if (_frameNumber % _frameInterval == 0) {
> > > QVideoFrame frame2(frame);
> > > frame2.map(QAbstractVideoBuffer::ReadOnly);
> > > QImage image;
> > >
> > > if (frame2.pixelFormat() == QVideoFrame::Format_BGR32) {
> > > image = QImage(frame2.bits(), frame2.width(), frame2.height(), QImage::Format_RGB32);
> > > image = image.rgbSwapped();
> > > } else {
> > > image = QImage(frame2.bits(), frame2.width(), frame2.height(), QVideoFrame::imageFormatFromPixelFormat(frame2.pixelFormat()));
> > > }
> > >
> > > frame2.unmap();
> > > QString filename = QString(_prefix).arg(_frameNumber);
> > > bool result = image.save(filename);
> > > qDebug() << Q_FUNC_INFO << filename << result;
> > > }
> > > _frameNumber ++;
> > > return true;
> > > }
> > >
> > > bool start(const QVideoSurfaceFormat &format) override {
> > > qDebug() << Q_FUNC_INFO;
> > > _format = format;
> > > _frameNumber = 0;
> > > QAbstractVideoSurface::start(format);
> > > return true;
> > > }
> > > void stop() override {
> > > qDebug() << Q_FUNC_INFO;
> > > QAbstractVideoSurface::stop();
> > > }
> > > QList<QVideoFrame::PixelFormat> supportedPixelFormats(QAbstractVideoBuffer::HandleType handleType) const override
> > > {
> > > Q_UNUSED(handleType);
> > > return QList<QVideoFrame::PixelFormat>()
> > > << QVideoFrame::Format_ARGB32
> > > << QVideoFrame::Format_ARGB32_Premultiplied
> > > << QVideoFrame::Format_RGB32
> > > << QVideoFrame::Format_RGB24
> > > << QVideoFrame::Format_RGB565
> > > << QVideoFrame::Format_RGB555
> > > << QVideoFrame::Format_ARGB8565_Premultiplied
> > > << QVideoFrame::Format_BGRA32
> > > << QVideoFrame::Format_BGRA32_Premultiplied
> > > << QVideoFrame::Format_BGR32
> > > << QVideoFrame::Format_BGR24
> > > << QVideoFrame::Format_BGR565
> > > << QVideoFrame::Format_BGR555
> > > << QVideoFrame::Format_BGRA5658_Premultiplied
> > > << QVideoFrame::Format_AYUV444
> > > << QVideoFrame::Format_AYUV444_Premultiplied
> > > << QVideoFrame::Format_YUV444
> > > << QVideoFrame::Format_YUV420P
> > > << QVideoFrame::Format_YV12
> > > << QVideoFrame::Format_UYVY
> > > << QVideoFrame::Format_YUYV
> > > << QVideoFrame::Format_NV12
> > > << QVideoFrame::Format_NV21
> > > << QVideoFrame::Format_IMC1
> > > << QVideoFrame::Format_IMC2
> > > << QVideoFrame::Format_IMC3
> > > << QVideoFrame::Format_IMC4
> > > << QVideoFrame::Format_Y8
> > > << QVideoFrame::Format_Y16
> > > << QVideoFrame::Format_Jpeg
> > > << QVideoFrame::Format_CameraRaw
> > > << QVideoFrame::Format_AdobeDng;
> > > }
> > >
> > >
> > > };
> > >
> > > // Command line: extractframes format interval
> > > // format:QString, with %1 = frame number
> > > // Example:
> > > // extractframes filename.mp4 image_%1.png 30
> > >
> > > int main(int argc, char *argv[])
> > > {
> > > QGuiApplication a(argc, argv);
> > > QMediaPlayer player;
> > > VideoSurface surface(argv[2], QString(argv[3]).toInt());
> > > QObject::connect(&player, &QMediaPlayer::mediaStatusChanged, [=]( QMediaPlayer::MediaStatus status ) {
> > > qDebug() << Q_FUNC_INFO << status;
> > > });
> > > QObject::connect(&player, QOverload<QMediaPlayer::Error>::of(&QMediaPlayer::error), [=]( QMediaPlayer::Error error ) {
> > > qDebug() << Q_FUNC_INFO << error;
> > > });
> > > QObject::connect(&player, &QMediaPlayer::stateChanged, [=]( const QMediaPlayer::State &state ) {
> > > qDebug() << Q_FUNC_INFO << state;
> > > if (QMediaPlayer::StoppedState == state) qApp->quit();
> > > });
> > >
> > > player.setMedia(QUrl::fromLocalFile(argv[1]));
> > > player.setVideoOutput(&surface);
> > > player.setMuted(true);
> > >
> > > player.play();
> > >
> > > return a.exec();
> > > }
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> >
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