openh264enc: fix broken sps/pps header generation

This was putting a truncated SPS into the initial header instead
of the PPS because it was always reading from the beginning of the
bitstream buffer (pBsBuf) and not from the offset where the current
NAL is at in the bitstream buffer (psBsBuf + nal_offset).

This was broken in commit 17113695.

Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/issues/1576

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2178>

1 files changed, 7 insertions, 2 deletions

diff --git a/ext/openh264/gstopenh264enc.cpp b/ext/openh264/gstopenh264enc.cpp
index b8b80c491..103794197 100644
--- a/ext/openh264/gstopenh264enc.cpp
+++ b/ext/openh264/gstopenh264enc.cpp
@@ -1042,8 +1042,13 @@ gst_openh264enc_handle_frame (GstVideoEncoder * encoder,
           if (j > 0)
             nal_offset = nal_offset + frame_info.sLayerInfo[i].pNalLengthInByte[j-1];
           nal_type = ((* (frame_info.sLayerInfo[i].pBsBuf + nal_offset + 4)) & 0x1f);
-          if (nal_type == NAL_SPS || nal_type == NAL_PPS)
-            gst_buffer_fill (hdr, nal_offset, frame_info.sLayerInfo[i].pBsBuf, frame_info.sLayerInfo[i].pNalLengthInByte[j]);
+          /* Note: This only works if SPS/PPS are the first two NALs in which case
+           * nal_offset is the same for both the output and the bitstream buffer */
+          if (nal_type == NAL_SPS || nal_type == NAL_PPS) {
+            gst_buffer_fill (hdr, nal_offset,
+                frame_info.sLayerInfo[i].pBsBuf + nal_offset,
+                frame_info.sLayerInfo[i].pNalLengthInByte[j]);
+          }
         }
         headers = g_list_append (headers, gst_buffer_ref (hdr));
     }