QMediaPlayer 在 Ubuntu 16.04 / Qt 5.6 上不播放任何内容

Question

我在 Ubuntu 16.04 上使用官方 Qt 5.6 SDK，当我尝试播放 mp3 文件时，我得到了：

defaultServiceProvider::requestService(): no service found for - "org.qt-project.qt.mediaplayer"

代码很简单：

mMediaPlayer->setMedia(QUrl::fromLocalFile(myMp3File));
mMediaPlayer->play();

这可以在 Android 上运行，并且之前可以在我的 Ubuntu 14.04 机器上运行。我错过了什么？默认情况下似乎已经安装了所有必需的 gstreamer（按文档）的东西，但它仍然不起作用：

$ dpkg -l | grep gstream
ii  gir1.2-gstreamer-1.0                                 1.8.2-1~ubuntu1                                             amd64        GObject introspection data for the GStreamer library
ii  gstreamer1.0-alsa:amd64                              1.8.2-1ubuntu0.1                                            amd64        GStreamer plugin for ALSA
ii  gstreamer1.0-clutter-3.0                             3.0.18-1                                                    amd64        Clutter PLugin for GStreamer 1.0
ii  gstreamer1.0-fluendo-mp3:amd64                       0.10.32.debian-1                                            amd64        Fluendo mp3 decoder GStreamer 1.0 plugin
ii  gstreamer1.0-libav:amd64                             1.8.2-1~ubuntu1                                             amd64        libav plugin for GStreamer
ii  gstreamer1.0-plugins-bad:amd64                       1.8.2-1ubuntu0.1                                            amd64        GStreamer plugins from the "bad" set
ii  gstreamer1.0-plugins-bad-faad:amd64                  1.8.2-1ubuntu0.1                                            amd64        GStreamer faad plugin from the "bad" set
ii  gstreamer1.0-plugins-bad-videoparsers:amd64          1.8.2-1ubuntu0.1                                            amd64        GStreamer videoparsers plugin from the "bad" set
ii  gstreamer1.0-plugins-base:amd64                      1.8.2-1ubuntu0.1                                            amd64        GStreamer plugins from the "base" set
ii  gstreamer1.0-plugins-base-apps                       1.8.2-1ubuntu0.1                                            amd64        GStreamer helper programs from the "base" set
ii  gstreamer1.0-plugins-good:amd64                      1.8.2-1ubuntu0.1                                            amd64        GStreamer plugins from the "good" set
ii  gstreamer1.0-plugins-ugly:amd64                      1.8.2-1ubuntu0.1                                            amd64        GStreamer plugins from the "ugly" set
ii  gstreamer1.0-plugins-ugly-amr:amd64                  1.8.2-1ubuntu0.1                                            amd64        GStreamer plugins from the "ugly" set
ii  gstreamer1.0-pulseaudio:amd64                        1.8.2-1ubuntu0.1                                            amd64        GStreamer plugin for PulseAudio
ii  gstreamer1.0-tools                                   1.8.2-1~ubuntu1                                             amd64        Tools for use with GStreamer
ii  gstreamer1.0-x:amd64                                 1.8.2-1ubuntu0.1                                            amd64        GStreamer plugins for X11 and Pango
ii  libgstreamer-plugins-bad1.0-0:amd64                  1.8.2-1ubuntu0.1                                            amd64        GStreamer development files for libraries from the "bad" set
ii  libgstreamer-plugins-base1.0-0:amd64                 1.8.2-1ubuntu0.1                                            amd64        GStreamer libraries from the "base" set
ii  libgstreamer-plugins-good1.0-0:amd64                 1.8.2-1ubuntu0.1                                            amd64        GStreamer development files for libraries from the "good" set
ii  libgstreamer1.0-0:amd64                              1.8.2-1~ubuntu1                                             amd64        Core GStreamer libraries and elements
ii  libreoffice-avmedia-backend-gstreamer                1:5.1.4-0ubuntu1                                            amd64        GStreamer backend for LibreOffice

...当然，我的声音在其他方面也很完美。

Answer 1

首先，使用 QT_DEBUG_PLUGINS=1 运行您的应用程序以查看插件错误。

如果您看到有关“libgstaudio-0.10.so.0”的错误，这是 GStreamer 版本问题。官方的 Qt 二进制文件似乎需要 GStreamer 0.10。

我找到的解决方案：

• 使用您的包管理器，使用您的发行版随附的 libqt：这是我找到的最佳解决方案，因为它是使用正确的 GStreamer 版本构建的。我使用不同的 chroot 为嵌入不同 GStreamer 版本的发行版制作包。
• Compile Qt from source to enable Gstreamer 1.0：未测试
• 安装 Gstreamer 0.10：我不推荐此选项，或者如果需要，请使用具有较旧发行版的 chroot。