Per specification in 2.14.2 "For PES packetization, no specific data alignment constraints apply". So we should not advertise NAL alignment.
This bug was introduced at the same moment the alignment field was introduced 10 years ago. The plan was that alignment=none (or no alignment field) was to be used for mpegtsdemux, but no one noticed the error. The reason is that at the same moment, everything dealing with H264 started defaulting to AU alignment.
https://bugzilla.gnome.org/show_bug.cgi?id=606662#c22
This patch will have a side effect that a parser is now needed after the tsdemux element. The following pipeline will not negotiate anymore as the mpegtsmux element requires alignment={nal,au}.
... ! tsdemux ! mpegtsmux ! ...As a side effect, anyone that forked from tsdemux should updated their code to fix this bug.