Nvv4l2decoder stuck on caps changing

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

We use nvv4l2decoder to decode h.265 simulcast stream on Xavier.
When stream changes it’s caps (because layer of simulcast is changing) then decoder stuck.
In logs I can see last message from decoder:
0:05:35.555564239 24543 0x7f74003190 DEBUG videodecoder gstvideodecoder.c:690:gst_video_decoder_setcaps:<nvv4l2decoder4> Checking if caps changed old video/x-h265, stream-format=(string)byte-stream, alignment=(string)au, width=(int)1280, height=(int)720, framerate=(fraction)30/1, chroma-format=(string)4:2:0, bit-depth-luma=(uint)8, bit-depth-chroma=(uint)8, parsed=(boolean)true, profile=(string)main, tier=(string)main, level=(string)3.1 new video/x-h265, stream-format=(string)byte-stream, alignment=(string)au, width=(int)858, height=(int)480, framerate=(fraction)30/1, chroma-format=(string)4:2:0, bit-depth-luma=(uint)8, bit-depth-chroma=(uint)8, parsed=(boolean)true, profile=(string)main, tier=(string)main, level=(string)3
After that - no any frames from decoder and all pipeline stops to work.

This behavior is also possible without simulcast, when caps cumming too fast, even if they are not changing.

2 Likes
3

Hi,
Please share your release version( $ head -1 /etc/nv_tegra_release ).
And could you try avdec_h265? By default it does not support dynamic resolution change in gstreamer. You may hit it in using software decoder.

4 
$ head -1 /etc/nv_tegra_release
# R32 (release), REVISION: 4.4, GCID: 23942405, BOARD: t186ref, EABI: aarch64, DATE: Fri Oct 16 19:37:08 UTC 2020

Using of software decode is not an option for us.
Is it possible to workaround it somehow ? For example: recreate decoder as soon as caps changed ?

5

Hi,
Downstream elements are initialized with identical resolution. If the resolution changes, the downstream pipeline has to be terminated and re-initialized. Do you have RTSP source(s) in your usecase? Generally the resolution is fixed in video playback. Please share your gstreamer pipeline for reference.

6

Our pipeline: webrtcbin → depayloader → parser → nv4l2decoder → nvvidconv → appsink
WebRTC supports resolution changes on the fly, so we need to handle it in our pipeline.