Porting jetson libs to new linux version issues

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
1

Ok, so probably not an issue I expect to get a ton of support for, but I have been working on porting jetson libs to libreelec. For the most part it all works(Vulkan, X, …) at leas the parts I need. Small problem when trying to get the decoder to work with ffmeg, which doesnt happen in ubuntu…

If I modify NVV4lElementPlane.cpp then I can get jetson-ffmpeg(nvmpi) lib to work, but it crashes on decoder close, with a double free or corruption out issue. Without modified nvv4lElementPlane.cpp, the decoder doesnt start, due to issue in deinitPlane function.

If I use nvv4l2dec all I get is a segfault on decoder open.

any thoughts on libs that have to be in aarch64-linux-gnu/{tegra, tegra-egl} I did find that libv4l extensions must follow this path, but the rest of the libs are a bit of a mystery to me…

here is how I am installing bsp libs, note this is still rough and still needs support for other L4T devices added. Lakka-LibreELEC/package.mk at Lakka-v4.x-new-jetson-ffmpeg-patches · GavinDarkglider/Lakka-LibreELEC · GitHub

Here is modified NvV4LElementPlane.cpp That works with nvmpi lib, but has issues on decoder close.

I would just dump the libs the way they are in ubuntu, which has worked in other distro ports(Arch, and fedora), but there is no way to run ldconfig in lakka/libreelec, as it is a squashfs system image, with minimal tools(no ldconfig, even if linker cache could be updated)

Any thoughts on fixing these lib issues(As from what I can tell that is where the problem is) or a new directions to look in would be helpful.

gdb output from ffmpeg with libnvmpi:

Thread 11 "retroarch" received signal SIGABRT, Aborted. [Switching to Thread 0x7f70424f70 (LWP 4916)] __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:49 49 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory. (gdb) bt #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:49 #1 0x0000007f7858cf74 in __GI_abort () at abort.c:79 #2 0x0000007f785d7c44 in __libc_message (action=action@entry=do_abort, fmt=fmt@entry=0x7f78691c90 "%s\n") at ../sysdeps/posix/libc_fatal.c:155 #3 0x0000007f785df68c in malloc_printerr (str=str@entry=0x7f7868d678 "free(): invalid pointer") at malloc.c:5389 #4 0x0000007f785e179c in free_check (mem=0x13a8fd0, caller=<optimized out>) at hooks.c:255 #5 0x0000007f7792bc90 in NvDdkVicFreeSession () from /usr/lib/libnvddk_vic.so #6 0x0000007f77cd1174 in NvBufferSessionDestroy () from /usr/lib/libnvbuf_utils.so.1.0.0 #7 0x0000007f7802aa00 in dec_capture_loop_fcn (arg=0xedebc0) at ../nvmpi_dec.cpp:316 #8 0x0000007f78881ddc in std::execute_native_thread_routine (__p=0xfbd2e0) at /home/gavin/Lakka-LibreELEC/build.Lakka-Switch.aarch64/build/gcc-10.2.0/libstdc++-v3/src/c++11/thread.cc:80 #9 0x0000007f7a366f14 in start_thread (arg=0x0) at pthread_create.c:463 #10 0x0000007f78639e1c in thread_start () at ../sysdeps/unix/sysv/linux/aarch64/clone.S:78

and I will post output of nv4l2_dec codec once I have built a proper debug build for that.

3

Hi,
Please refer to developer guide and follow it for the implementation.

FYR, here is a post about building the source code:
Jetson TX2 and FFmpeg - Can't initialize nvrm channel - #5 by DaneLLL

4

Thank you for your response, but this doesnt really apply, since I already have all of this, and all the nvv4l2dec does is segfault in ffmpeg on my distro I am building. I am not using ubuntu as a base system, or any debian based system. I am using LibreELEC which is a stripped down distribution for media centers. The last piece of the puzzle is working out the decoder stuff, which seems to crash in the nvidia libs. I have narrowed this down to the way something else is compiled, but since I dont have the info needed to debug, as the libs dont spit out anything other than the functions being called in the lib that the error occurs, I am at a bit of a loss.

for example with nvv4l2 decoder, I have been able to trace the issue to this line. https://gitlab.com/switchroot/switch-l4t-multimedia/FFmpeg/-/blob/4.4-l4t/libavcodec/nvv4l2_dec.c#L928

The moment it calls NVBuffer it segfaults, and since I cant see what is happening in that function, I have no idea where to even look.

5

Hi,
Please check if you put the jetson_multimedia_api samples in

/usr/src/jetson_multimedia_api

And can run 00_video_decode and 01_video_encode samples successfully. The ffmpeg package is based on jetson_multimedia_api. Please make sure the samples can be built/run successfully.

6

Ok, so upon further research with gdb, where I basically started dumping values getting passed to libs, to find out that my compiler (GCC 10.x) is optimizing out variables that dont have a value set when they are defined. Got it kind of working using nvv4l2 decoder, now to figure out the next issue, which is about 10 minutes in the stream crashes.

8

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