[Live-devel] NAL Unit FU header

[Ross Finlayson]

> On Mar 31, 2023, at 4:45 AM, Milos Jakovljevic <milos.jakovljevic at nittbit.com> wrote:
> 
> Hi everyone,
> 
> I'm receiving a 4K HEVC stream from the remote server. All the NAL units seem to be fragments but for some reason NAL type is always either 1 or 19 apart from Non-VCL types. 
> 
> I'm trying to figure out how I would recognize if its a fragment ? Am i missing something?

Your question was rather vague - you don’t explain exactly how you’re using the “LIVE555 Streaming Media” code.  But from the context, I presume that you’re using it as a RTSP client, rather than as a RTSP server.

Note that the LIVE555 RTSP/RTP implementation automatically handles fragmentation/defragmentation of H.264 (and H.265) NAL units into RTP packets - at both the server end and the client end.  As a programmer, you don’t need to concern yourself with RTP fragmentation.  The LIVE555 RTSP client code will deliver complete NAL units - so that’s what you should be receiving: Complete NAL units (which might include video frame ‘slices’ - not necessarily complete video frames).

A reminder that if you’re testing the LIVE555 RTSP client implementation against a remote RTSP stream (whether or not its server is also written using the LIVE555 code), then the best way to begin is using our command-line “openRTSP” RTSP client; see
	http://live555.com/openRTSP/


(You can also use VLC - as it uses the LIVE555 code (when acting as a RTSP client) - but the “openRTSP” code is easier to understand.)

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/