Nvv4l2h265enc SliceIntraRefreshInterval

[JimenaSalas]

Hi,

I would like to know what is the difference between the iframeinterval and the SliceIntraRefreshInterval properties of the h265 encoder, since both of them seem to output the same frame I-P frame structure, and this does not happen with the h264 encoder.

Here are the pipelines to reproduce:

gst-launch-1.0 videotestsrc num-buffers=100 ! nvvidconv ! nvv4l2h264enc iframeinterval=5 ! h264parse ! filesink location=i-5-frames.h264
gst-launch-1.0 videotestsrc num-buffers=100 ! nvvidconv ! nvv4l2h264enc SliceIntraRefreshInterval=5 ! h264parse ! filesink location=intra-5-frames.h264
gst-launch-1.0 videotestsrc num-buffers=100 ! nvvidconv ! nvv4l2h265enc iframeinterval=5 ! h265parse ! filesink location=i-5-frames.h265
gst-launch-1.0 videotestsrc num-buffers=100 ! nvvidconv ! nvv4l2h265enc SliceIntraRefreshInterval=5 ! h265parse ! filesink location=intra-5-frames.h265

Thanks in advance.

[DaneLLL]

Hi,
idrinterval is interval of IDR frames. SliceIntraRefreshInterval is interval of I frames. IDR and I frames are slightly different.

[JimenaSalas]

Hi @DaneLLL ,

Thanks for your answer, but I asked about iframeinterval, not idrinterval. Could you explain the difference between the iframeinterval and SliceIntraRefreshInterval properties or they both do the same?

[DaneLLL]

Hi,
SliceIntraRefreshInterval has to be set along with slice-header-spacing. Please refer to the sample pipeline:

$ gst-launch-1.0 videotestsrc num-buffers=100 pattern=1 ! video/x-raw,width=1920,height=1080 ! nvvidconv ! nvv4l2h264enc slice-header-spacing=900 SliceIntraRefreshInterval=30 iframeinterval=30 idrinterval=60 bitrate=12000000 ! h264parse ! video/x-h264,stream-format=byte-stream ! filesink location=b.h264

However, both SliceIntraRefreshInterval and iframeinterval take effect in the condition. So if you set the two properties to two different values, the interval of I frames may not be fixed. We would suggest set to identical value for avoid confusion.
Without setting slice-header-spacing, SliceIntraRefreshInterval does not take effect.

There is an issue about setting slice-header-spacing. If you would like to run in the mode, please apply the patch and rebuild libgstnvvideo4linux2.so:

diff --git a/gst-v4l2/gstv4l2h264enc.c b/gst-v4l2/gstv4l2h264enc.c
index fe2806c..6a6cfe7 100644
--- a/gst-v4l2/gstv4l2h264enc.c
+++ b/gst-v4l2/gstv4l2h264enc.c
@@ -634,7 +634,11 @@ gst_v4l2_h264_enc_slice_header_spacing (GstV4l2Object * v4l2object,
   struct v4l2_ext_controls ctrls;
   gint ret;
   v4l2_enc_slice_length_param param =
-      { bit_packetization, slice_header_spacing };
+      { V4L2_ENC_SLICE_LENGTH_TYPE_MBLK, slice_header_spacing };
+
+  if (bit_packetization) {
+    param.slice_length_type = V4L2_ENC_SLICE_LENGTH_TYPE_BITS;
+  }
 
   memset (&control, 0, sizeof (control));
   memset (&ctrls, 0, sizeof (ctrls));
diff --git a/gst-v4l2/gstv4l2h265enc.c b/gst-v4l2/gstv4l2h265enc.c
index 3ee6bcd..6ea8c1d 100644
--- a/gst-v4l2/gstv4l2h265enc.c
+++ b/gst-v4l2/gstv4l2h265enc.c
@@ -431,7 +431,11 @@ gst_v4l2_h265_enc_slice_header_spacing (GstV4l2Object * v4l2object,
   struct v4l2_ext_controls ctrls;
   gint ret;
   v4l2_enc_slice_length_param param =
-      { bit_packetization, slice_header_spacing };
+      { V4L2_ENC_SLICE_LENGTH_TYPE_MBLK, slice_header_spacing };
+
+  if (bit_packetization) {
+    param.slice_length_type = V4L2_ENC_SLICE_LENGTH_TYPE_BITS;
+  }
 
   memset (&control, 0, sizeof (control));
   memset (&ctrls, 0, sizeof (ctrls));