gstreamermm:如何提取 Gst::P layBin 的最后一帧视频

gstreamermm: How can I extract the last video frame of a Gst::PlayBin

本文关键字：最后 视频 layBin 一帧 Gst 何提取 提取 gstreamermm      更新时间：2023-10-16

我尝试使用 gstreamermm 1.0 提取视频的最后一帧，并与示例 https://github.com/GNOME/gstreamermm/blob/master/examples/media_player_gtkmm/player_window.cc 密切合作，但我只得到白色像素。

如何将流的最后一帧视频提取为原始 rgba 或 bgra 数据？

void
MediaStream::setup ()
{
    player = Gst::PlayBin::create ("player");
    vsink  = Gst::XImageSink::create ("vsink");
    player -> set_property ("video-sink", vsink);
    player -> signal_video_changed () .connect (sigc::mem_fun (*this, &MediaStream::on_video_changed));
}

void
MediaStream::on_video_changed ()
{
    Glib::RefPtr <Gst::Pad> pad = player -> get_video_pad (0);
    if (pad)
        pad -> add_probe (Gst::PAD_PROBE_TYPE_BUFFER, sigc::mem_fun (*this, &MediaStream::on_video_pad_got_buffer));
}
Gst::PadProbeReturn
MediaStream::on_video_pad_got_buffer (const Glib::RefPtr <Gst::Pad> & pad, const Gst::PadProbeInfo & data)
{
    const auto width  = vsink -> get_width ();
    const auto height = vsink -> get_height ();

    std::vector <uint8_t> image (width * height * 4);

    // Got no data
    data .get_buffer () -> extract (0, image .data (), image .size ());

    return Gst::PAD_PROBE_OK;
}

错过C++的 C 版本工作正常：

const auto sample = gst_base_sink_get_last_sample (vsink -> Gst::BaseSink::gobj ());
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