Closed aa-bamboo closed 2 years ago
chubinou
commented
2 years ago Hi,
On which platform do you observe the issue?
Do you only observe it on next? or on sometime while opening the first media
Do you still have the issue if you use EGL backend of Qt (exporting QT_XCB_GL_INTEGRATION=xcb_egl) and remove the "eglQueryString" hack
Do you still have the issue if you disable accelerated hardware with --no-hw-dec
aa-bamboo
commented
2 years ago On which platform do you observe the issue?
The issue exist on all three platforms: Windows, Linux, MacOS X.
Do you only observe it on next? or on sometime while opening the first media
Crash usually occurs on next file. But sometimes on first one.
Do you still have the issue if you use EGL backend of Qt (exporting QT_XCB_GL_INTEGRATION=xcb_egl) and remove the "eglQueryString" hack.
Yes it crashes. I tried this proposal and application crashes. However, according to the forum's response additional env parameter QT_XCB_GL_INTEGRATION is not required. But after changes you proposed applicatoin starts without "eglQueryString" hack.
Do you still have the issue if you disable accelerated hardware with --no-hw-dec
Yes.
chubinou
commented
2 years ago However, according to the forum's response additional env parameter QT_XCB_GL_INTEGRATION is not required
no that's not a requirement, but the decoder is set up differently when using EGL or GLX open gl implementation, so the question may help to know where to look at.
On a side note, when using GLX (in the current state of things) I think that you should rather blacklist all egl functions (functions starting with "egl") this avoids having vlc thinking he has EGL implementation and making calls to unimplemented functions.
what version of VLC did you you test (which hash or the date of the nightly)
I guess that the stack trace you provided is from a linux, and that the FFMPEG is the one from the OS, if my suppositions are right can you install libavcodec58-dbgsym (or the one corresponding to you OS version) add this to your /apt/source.list on ubuntu, to be able to install debug symbols (here for ubuntu 20.04 focal, adapt for your OS version)
deb http://ddebs.ubuntu.com focal main restricted universe multiverse
deb http://ddebs.ubuntu.com focal-updates main restricted universe multiverse
deb http://ddebs.ubuntu.com focal-proposed main restricted universe multiversewhen providing the statck trace, can you show the state of each thread:
in gdb enter the command thread apply all bt
also can you provide verbose logs "-vvvv" of a case where you reproduce the issue (and specify on which plateform this happened)
chubinou
commented
2 years ago by the way, if you want to check whether Qt is using EGL or not you can retrieve its context (it should be non-null when using EGL)
///m_context = new QOpenGLContext(this);
QPlatformNativeInterface *nativeInterface = QGuiApplication::platformNativeInterface();
bool isUsingEGL = nativeInterface->nativeResourceForContext("eglContext", m_context) != nullptr;Note that I'm not really sure how the QOpenGLContext works now with Qt6 on windows and OSX, In Qt5, it use to leverage ANGLE on windows which is an EGL implementation on top of D3D11, I but as far as I know they removed ANGLE, so they probably use the system OpenGL implementation which is WGL, but I don't know how does it interact with their QML backend which should use D3D (unless you force it to use OpenGL)
aa-bamboo
commented
2 years ago what version of VLC did you you test (which hash or the date of the nightly)
The latest. I rebuild master branch from gitlab repo for linux daily. Also I update windows library from nightly builds.
Debug info:
Using libvlc version: "4.0.0-dev Otto Chriek"
Volume set 0.399994
libva info: VA-API version 1.7.0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/iHD_drv_video.so
libva info: Found init function __vaDriverInit_1_7
libva info: va_openDriver() returns 0
[00007fff10119450] vaapi generic: Using Intel iHD driver for Intel(R) Gen Graphics - 20.1.1 ()Stacktrace Strange. Now I have segfault in different place...
1 QOpenGLFramebufferObject::texture qopenglframebufferobject.cpp 1235 0x7fffe4206390
2 Vlc::VideoFrame::VideoFrame videoframe.cpp 26 0x7fff62beea48
3 __gnu_cxx::new_allocator<Vlc::VideoFrame>::construct<Vlc::VideoFrame, QOpenGLFramebufferObject *> new_allocator.h 146 0x7fff62bee4e5
4 std::allocator_traits<std::allocator<Vlc::VideoFrame>>::construct<Vlc::VideoFrame, QOpenGLFramebufferObject *> alloc_traits.h 483 0x7fff62bee3c4
5 std::_Sp_counted_ptr_inplace<Vlc::VideoFrame, std::allocator<Vlc::VideoFrame>, (__gnu_cxx::_Lock_policy)2>::_Sp_counted_ptr_inplace<QOpenGLFramebufferObject *> shared_ptr_base.h 548 0x7fff62bee0ce
6 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count<Vlc::VideoFrame, std::allocator<Vlc::VideoFrame>, QOpenGLFramebufferObject *> shared_ptr_base.h 679 0x7fff62bedcfe
7 std::__shared_ptr<Vlc::VideoFrame, (__gnu_cxx::_Lock_policy)2>::__shared_ptr<std::allocator<Vlc::VideoFrame>, QOpenGLFramebufferObject *> shared_ptr_base.h 1344 0x7fff62bedaca
8 std::shared_ptr<Vlc::VideoFrame>::shared_ptr<std::allocator<Vlc::VideoFrame>, QOpenGLFramebufferObject *> shared_ptr.h 359 0x7fff62bed7cf
9 std::allocate_shared<Vlc::VideoFrame, std::allocator<Vlc::VideoFrame>, QOpenGLFramebufferObject *> shared_ptr.h 702 0x7fff62bed3cd
10 std::make_shared<Vlc::VideoFrame, QOpenGLFramebufferObject *> shared_ptr.h 718 0x7fff62becdfb
11 Vlc::OpenGLVideoStream::getVideoFrame openglvideostream.cpp 70 0x7fff62bec128
12 VideoStream::frameUpdated videostream.cpp 65 0x7fff78441df5
13 QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, void (Vlc::OpenGLVideoStream:: *)()>::call(void (Vlc::OpenGLVideoStream:: *)(), Vlc::OpenGLVideoStream *, void * *) qobjectdefs_impl.h 171 0x7fff62bede63
14 QtPrivate::FunctionPointer<void (Vlc::OpenGLVideoStream:: *)()>::call<QtPrivate::List<>, void>(void (Vlc::OpenGLVideoStream:: *)(), Vlc::OpenGLVideoStream *, void * *) qobjectdefs_impl.h 208 0x7fff62bedbf0
15 QtPrivate::QSlotObject<void (Vlc::OpenGLVideoStream:: *)(), QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void * *, bool *) qobjectdefs_impl.h 419 0x7fff62bed96b
16 QObject::event qobject.cpp 1356 0x7ffff245ea7c
17 QApplicationPrivate::notify_helper qapplication.cpp 3337 0x7ffff341e432
18 QCoreApplication::notifyInternal2 qthread_p.h 316 0x7ffff240dfba
19 QCoreApplicationPrivate::sendPostedEvents qcoreapplication.cpp 1848 0x7ffff2410edc
20 postEventSourceDispatch qeventdispatcher_glib.cpp 279 0x7ffff26b14c3
21 g_main_context_dispatch 0x7fffef91317d
22 ?? 0x7fffef913400
23 g_main_context_iteration 0x7fffef9134a3
24 QEventDispatcherGlib::processEvents qeventdispatcher_glib.cpp 429 0x7ffff26b0e4a
25 QEventLoop::exec qflags.h 144 0x7ffff241a1eb
26 QCoreApplication::exec qflags.h 110 0x7ffff2415dae
27 main main.cpp 117 0x5555555e1737 Strange. Now I have segfault in different place...
you should probably take the m_text_lock during resize and cleanup, this looks like a use after free.
The latest. I rebuild master branch from gitlab repo for linux daily
hum, Ok, but that's a bit harder to know whether I'm investigating the same bug or not with a moving target, code has changed in VLC since your report post on the forum, notably in the VA-API part.
To be clear: I do reproduce a crash with your code (and our sample QtOpenGL app), but it's working working correctly when forcing egl and when disabling hw-acceleration, not saying that you should not use glx, but I wonder if we're looking at the same issue.
debug info [...]
you need to add "-vvvv" in libvlc arguments.
by the way: using in instance.cpp the line argv[i] = static_cast<char *>(args.at(i).toUtf8().data()); is unsafe as toUtf8 will create a temporary QString that will be destroyed when leaving the assignation, so your pointer points to an unassigned memory space. You should probably do the qstrdup like you do on windows
aa-bamboo
commented
2 years ago Thank you. Let me apply suggestions. Also I'll share verbose log and synchronize library version across every platform, then I'll share that version number with you to be using the same build.
chubinou
commented
2 years ago Hi, can you try to build VLC with this patch ?
https://code.videolan.org/videolan/vlc/-/merge_requests/2017
aa-bamboo
commented
2 years ago Hi, can you try to build VLC with this patch ?
https://code.videolan.org/videolan/vlc/-/merge_requests/2017
I'll try
aa-bamboo
commented
2 years ago you should probably take the
m_text_lockduring resize and cleanup, this looks like a use after free.
Adding lock m_text_lock into both resize and cleanup causes deadlock. Adding it separately into resize or cleanup doesn't take any effect.
To be clear: I do reproduce a crash with your code (and our sample QtOpenGL app), but it's working working correctly when forcing egl and when disabling hw-acceleration, not saying that you should not use glx, but I wonder if we're looking at the same issue.
It seems that it is the same issue.
you need to add "-vvvv" in libvlc arguments.
I've added it into arguments. But there is full log:
VLC ARGS: QList("-vvvv")
Using libvlc version: "4.0.0-dev Otto Chriek"
qml: playpreview
Volume set 0.399994
libva info: VA-API version 1.7.0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/iHD_drv_video.so
libva info: Found init function __vaDriverInit_1_7
libva info: va_openDriver() returns 0
[00007fec54119790] vaapi generic: Using Intel iHD driver for Intel(R) Gen Graphics - 20.1.1 ()
[00007fec541609d0] gl gl error: Could not create interop
[00007fec5406b330] main video output error: video output display creation failed
QSGTexture anisotropy levels are not currently supported
Texture 0x7fecd0a27c10 () used with different accesses within the same pass, this is not allowed.
Texture 0x7fecd08cd1a0 () used with different accesses within the same pass, this is not allowed.
qml: playpreview
[h264 @ 0x7fec701488c0] Discarding mismatching reference
[h264 @ 0x7fec701488c0] Discarding mismatching reference
[h264 @ 0x7fec701488c0] Missing reference picture, default is 0
[h264 @ 0x7fec701488c0] decode_slice_header error
[00007fec4001f950] vaapi generic: Using Intel iHD driver for Intel(R) Gen Graphics - 20.1.1 ()
[00007fec40005ce0] gl gl error: Could not create interop
[00007fec5406b330] main video output error: video output display creation failedby the way: using in
instance.cppthe lineargv[i] = static_cast<char *>(args.at(i).toUtf8().data());is unsafe astoUtf8will create a temporary QString that will be destroyed when leaving the assignation, so your pointer points to an unassigned memory space. You should probably do the qstrdup like you do on windows
Ok. Let me make changes.
chubinou
commented
2 years ago Adding lock m_text_lock into both resize and cleanup causes deadlock
yes obviously, as resize calls cleanup. In your case there isn't much value in calling cleanup as the texture will be released when reassigning the unique_ptr
for what it's worth I put my local changes on this branch https://github.com/chubinou/QuickVLC/commits/hotfixes
It seems that it is the same issue.
So ... does the patch I sent fixes your issue?
I've added it into arguments. But there is full log:
hum, that log is still incomplete, I suspect that this is linked to the issue with argv[i] = static_cast<char *>(args.at(i).toUtf8().data());
A complete log should look like this https://pastebin.com/G1a6rxXF
Now the upcomming issue it that you don't have hw accceleration with GLX (so on linux when Qt run with GLX backend), as we don't have an "interop" between VAAPI (the hw decoder) and GLX, only the EGL one is available at the moment.
aa-bamboo
commented
2 years ago Hi, can you try to build VLC with this patch ?
https://code.videolan.org/videolan/vlc/-/merge_requests/2017
The patch hasn't fixed the crash.
I started to play 4 videos one by one. And on the 4th file application has crashed.
The full log is here (I added args fix): LibVLC log
Next I'm going to apply and check changes from hotfixes branch.
aa-bamboo
commented
2 years ago for what it's worth I put my local changes on this branch https://github.com/chubinou/QuickVLC/commits/hotfixes
I checked and tested changes multiple times with different files. And there were no more crashes. Seems that issue has fixed. Let me clean up the code, and then I'll share the final results.
aa-bamboo
commented
2 years ago Update.
The patch https://code.videolan.org/videolan/vlc/-/merge_requests/2017 fixes crashes on some specific videos with specific codecs. Also it fixes "black screen" on some dvd's videos.
On other side changes from hotfix branch fix the crash while starting different files one by one.
So we need to apply both changes: from patch and from hotfixes branch.
chubinou
commented
2 years ago Seems that issue has fixed.
OK good news
So we need to apply both changes
for your information, the MR 2017 has been merged upstream
aa-bamboo
commented
2 years ago Thank you. Yes, I pulled an upstream
The library renders video frames using callbacks (libvlc_video_set_output_callbacks from libvlc v4.0.0) into OpenGL framebuffer. Then framebuffer's texture is used for QSGTexture object.
We use the last version of LibVLC v4.0.0 from "master" branch: nightly builds for Windows and MacOS X and daily recompiled from source version for Linux.
The main trouble now is a crash when we try to play one file after the previous one. The crash occurs unexpectedly.
Call-stack doesn't provide enough information (something with threads, all debug symbols are installed):