[FFmpeg-user] Nvidia Transcoding: Failing Using xstack (When Running Under systemd)

[Dennis Mungai]

On Mon, 18 Nov 2024, 11:33 pm Shane Warren, <shanew at innovsys.com> wrote:

> I have been trying to track down why when transcoding using xstack with
> nvidia decoding and encoding I get strange decoding issues in ffmpeg.
>
> Note: I use 2 1 minute long .ts files for this example if you want my
> inputs, they are available here (as input1.ts and input2.ts) :
>
>
> https://drive.google.com/drive/folders/1mZ8xiNvz5ez1ULlNsy5a3KhnhaqQ2Hgo?usp=drive_link
>
> I got the latest ffmpeg and tried this command (xstacking 2 videos into 1
> output):
>
> ffmpeg -y -threads 2 -nostats -loglevel verbose -probesize 5M
> -filter_threads 4 -threads 2 -re -fflags +genpts -fflags discardcorrupt  \
> -extra_hw_frames 2 -hwaccel cuda -hwaccel_output_format cuda -threads 2
> -thread_queue_size 4096 -heavy_compr 1 -thread_queue_size 4096 -re -i
> input1.ts \
> -extra_hw_frames 2 -hwaccel cuda -hwaccel_output_format cuda -threads 2
> -thread_queue_size 4096 -heavy_compr 1 -thread_queue_size 4096 -re -i
> input2.ts \
> -filter_complex "\
> [0:v:0]yadif_cuda=deint=interlaced,scale_cuda=768:432,hwdownload,format=nv12,fps=60000/1001[v0];
> \
> [1:v:0]yadif_cuda=deint=interlaced,scale_cuda=768:432,hwdownload,format=nv12,fps=60000/1001[v1];
> \
> [v0][v1] xstack=inputs=2:layout=0_0|0_h0[mosaic];\
> [mosaic]hwupload_cuda,scale_cuda=w=1280:h=720:format=yuv420p:force_original_aspect_ratio=decrease,hwdownload,format=yuv420p,pad=1280:720:(ow-iw)/2:(oh-ih)/2,hwupload_cuda[out0]"
> \
> -filter:a:0 "aresample=async=10000,volume=1.00" -c:a:0 ac3 -threads 2
> -ac:a:0 6 -ar:a:0 48000 -b:a:0 384k \
> -filter:a:1 "aresample=async=10000,volume=1.00" -c:a:1 ac3 -threads 2
> -ac:a:1 6 -ar:a:1 48000 -b:a:1 384k \
> -map "[out0]" -map "0:a:0" -map "1:a:0" \
> -c:v h264_nvenc -b:v 6000k -minrate:v 6000k -maxrate:v 6000k -bufsize:v
> 12000k -a53cc 1 -tune ll -zerolatency 1 -cbr 1 -forced-idr 1 -strict_gop 1
> -threads 2 -profile:v high -level:v 4.2 -bf:v 0 -g:v 30 \
> -f mpegts -muxrate 8238520 -pes_payload_size 1528 "udp://@
> 225.105.0.37:10102?pkt_size=1316&bitrate=8238520&burst_bits=10528&ttl=64"
>
> If you run that command in Ubuntu 22.04 it works 100% fine and transcodes
> till the end of the input file(s).
>
> What doesn't work is if you start that process under systemd
> non-interactively like so:
>
> systemd-run -S
>
> Then run that same command it will now fail in a strange way.
>
> Note: It's important that you try to output to multicast, if I try the
> same command outputting to a file, it works fine (my guess is any
> network-based output exhibits this behavior).
>
> You will see logs like this:
>
> [Parsed_scale_cuda_1 @ 0x55da86a03340] w:1920 h:1080 fmt:nv12 -> w:768
> h:432 fmt:nv12
>
> And the about 1-2 seconds before another log comes out.
>
> Eventually (after many stalls and logs) this log comes out and the
> transcode stops:
>
> [vost#0:0/h264_nvenc @ 0x55da86a3f780] Error submitting a packet to the
> muxer: Cannot allocate memory
>
> I attached GDB to ffmpeg when it is stalled and its inside trying to
> compile a cuda script.
>
> If I'm not doing xstack (I'm pretty sure this has to do with multiple
> inputs) nvidia does not stall.
>
> Does anyone have any idea what is happening here? I launch ffmpeg from a
> c++ wrapper daemon, if that daemon is started via systemd, then nvidia
> multiple inputs fail. However, if I launch my daemon by hand at a terminal,
> it works fine.
>
> Thanks
>


Paste the content of the systemd unit file here.
Logs from the same (systemctl status unit-name.service) will also assist.
That might help in understanding how and why the systemd unit is failing.

>