Crash report: https://crash-stats.mozilla.org/report/index/3ae53cf4-1c9f-449b-8c15-6f94a0220812

Reason: EXCEPTION_ACCESS_VIOLATION_WRITE

Top 10 frames of crashing thread:

0 vcruntime140.dll memcpy d:\agent\_work\1\s\src\vctools\crt\vcruntime\src\string\amd64\memcpy.asm:406
1 xul.dll mozilla::AudioCallbackDriver::MixerCallback dom/media/GraphDriver.cpp:1096
2 xul.dll mozilla::AudioMixer::FinishMixing dom/media/AudioMixer.h:58
3 xul.dll mozilla::MediaTrackGraphImpl::OneIterationImpl dom/media/MediaTrackGraph.cpp:1560
4 xul.dll mozilla::GraphRunner::Run dom/media/GraphRunner.cpp:139
5 xul.dll nsThread::ProcessNextEvent xpcom/threads/nsThread.cpp:1199
6 xul.dll mozilla::ipc::MessagePumpForNonMainThreads::Run ipc/glue/MessagePump.cpp:300
7 xul.dll MessageLoop::RunHandler ipc/chromium/src/base/message_loop.cc:373
8 xul.dll MessageLoop::Run ipc/chromium/src/base/message_loop.cc:355
9 xul.dll static nsThread::ThreadFunc xpcom/threads/nsThread.cpp:384

This appears to be a Windows-specific crash, from the looks of it mBuffer is NULL and we crash when we attempt to write into it. Note that there's other crashes under this signature happening at the same line but they seem to be crashing reading from aMixedBuffer however those stack traces appear less consistent and I'm not sure if the problem is related.

MediaStreamGraph related, most likely related to WebRTC. Daniel, ca you have a look?

Beginning investigation into crash.

Since the crash volume is low (less than 15 per week), the severity is downgraded to S3. Feel free to change it back if you think the bug is still critical.

For more information, please visit auto_nag documentation.

The signature changed here, I need to tweak it.