Hello, Replying to myself, I hope this can help other people.
Easier for debugging use -debug_ts and look at the line: muxer <- pts:18 pts_time:2 dts:18 dts_time:2 duration:1 duration_time:0.111111 size:24883254 latency(total:547.743ms, demux-decode: 133.354ms/24%, decode 403.334ms/73%) This will give out the ffmpeg latency (avoid starting and flushing packets). Which is what I measure myself but easier. And after more research in the libavcodec/cuviddec.c I found there is this tweak https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/cuviddec.c#L1049 Adding the "-flags +low_delay" will give you muxer <- pts:47 pts_time:5.222222 dts:47 dts_time:5.222222 duration:1 duration_time:0.111111 size:24883254 latency(total:104.805ms, decode 96.373ms/91%) So 105ms, which is quite nice :) If anyone as another trick, please let me know Thanks On Fri, 1 Nov 2024 at 18:06, Clément Péron <peron.c...@gmail.com> wrote: > > 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@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 _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
