[FFmpeg-user] Expected latency with RTSP/TCP H264 stream

[Clément Péron]

Hello,

I'm trying to have a low latency stream if possible, less than 500ms.
By "latency" I mean the delta between a frame is sent by the camera
and when it's received and decoded by FFMpeg until being available to
the stdout.

To measure it, I add an overlay from the camera side with the source timestamp
And I then add a timestamp on the ffmpeg side using the drawtext
plugin and output it as a BMP.

My measurement show:
1080p: 616ms
4k: 699ms

I use the Cuvid decoder with the following command:
./ffmpeg -allowed_media_types video -c:v h264_cuvid -err_detect
careful -fflags nobuffer -init_hw_device cuda:0 -max_port 65000
-min_port 5000 -nostats -re -rtsp_flags prefer_tcp -rtsp_transport tcp
-surfaces 8 -timeout 1000000 -i
rtsp://root:XXX@10.98.5.107:554/axis-media/media.amp -vf
"drawtext=text='%{localtime\:%Y/%m/%d %H\\\\\:%M\\\\\:%S.%N}': x=0:
y=50: fontcolor=white: fontsize=48: box=1: boxcolor=black at 0.5"
-pix_fmt rgb24 -vframes 1 output_image_X.bmp

Do you think reducing the latency to less than 500ms is doable?
Or is there some kind of limitation in the pipeline somewhere?

Thanks for your help