I'm working with gstreamer 1.18 (built with gst-build). I'm trying to use the lossless preset of the nvh265enc plugin. With the following pipeline, I can successfully use all presets except the lossless ones (lossless (6) and lossless-hp (7)):
gst-launch-1.0 videotestsrc ! nvh265enc preset=6 ! h265parse ! nvh265dec ! glimagesink
Whenever I set preset to 6 or 7, I get the following error.
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Got context from element 'sink': gst.gl.GLDisplay=context, gst.gl.GLDisplay=(GstGLDisplay)"\(GstGLDisplayX11\)\ gldisplayx11-0";
Got context from element 'nvh265dec0': gst.cuda.context=context, gst.cuda.context=(GstCudaContext)"\(GstCudaContext\)\ cudacontext0", cuda-device-id=(int)0;
ERROR: from element /GstPipeline:pipeline0/GstNvH265Enc:nvh265enc0: Could not configure supporting library.
Additional debug info:
../subprojects/gst-plugins-bad/sys/nvcodec/gstnvbaseenc.c(1712): gst_nv_base_enc_set_format (): /GstPipeline:pipeline0/GstNvH265Enc:nvh265enc0:
Failed to init encoder: 8
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
ERROR: from element /GstPipeline:pipeline0/GstNvH265Enc:nvh265enc0: Could not configure supporting library.
Additional debug info:
../subprojects/gst-plugins-bad/sys/nvcodec/gstnvbaseenc.c(1712): gst_nv_base_enc_set_format (): /GstPipeline:pipeline0/GstNvH265Enc:nvh265enc0:
Failed to init encoder: 8
ERROR: pipeline doesn't want to preroll.
Freeing pipeline ...
What's more puzzling is that the lossless preset works with the samples from the Nvidia Video Codec SDK 9.
Did I miss any additional configuration?
EDIT : finally I found that adding qp-const=0 or rc-mode=1 to nvh265enc worked.
Well, first of all, there is no difference between lossless and lossless-hp.
Second of all, Gstreamer is not the application that Nvidia natively supports. FFmpeg, on the other hand, is. For example B-frames as reference mode with its two submodes (middle and each) is not supported too in GS. See: https://forum.videohelp.com/threads/387613-Nvidia-h-265-hevc-lossless#post2509093
ffmpeg -vsync 0 -r 60 -hwaccel cuda -hwaccel_output_format cuda -i "in.mp4" -c:v hevc_nvenc -preset lossless "out.mp4"
P.S. Gstreamer supports lossless with rc-mode=1 or qp-const=0.