[FFmpeg-user] Intel libmfx Crash with Hardware Decoding

[Shane Warren]

I have a system with Intel Flex 140 cards and use ffmpeg to transcode video on an Ubuntu 22.x system. Through a lot of testing, I have come up with a flow that handles multicast h264 input (decoding using vaapi) with h264/h265 output using QSV. I wanted to use QSV decoding but if I used QSV decoding and QSV encoding, but QSV decoding seems to strip A53 captions (which I need).

I found one input stream that eventually crashes the vaapi decoder inside of libmfx.

The call stack ends up in some function in libfmx:

Program terminated with signal SIGSEGV, Segmentation fault.

#0  0x00007f14b22d9f88 in ?? () from /usr/lib/x86_64-linux-gnu/libmfx-gen.so.1.2.10

Is there a way to get symbols for libmfx so I can get a better bug report, or some suggestion on how to debug this.

I have switched this stream to software decoding then QSV encoding, and it is stable but obviously uses a bit more cpu.

An extra question is: Will the QSV hardware decoder ever support passing through a53 captions?

Thanks,

Shane Warren