> On Mar 31, 2023, at 9:33 PM, Milos Jakovljevic 
> <milos.jakovlje...@nittbit.com> wrote:
> 
> I'm currently using LIVE555 as an RTSP client in my library, and I'm 
> experiencing an issue with HEVC 4K streams. Specifically, when I decode NAL 
> units, I'm only able to view 1/3 of the picture, while the remaining 2/3 is 
> green (you can view an example here: https://ibb.co/C8yFygm).
> 
> Upon further investigation, I discovered that I'm receiving three NAL units 
> with the same timestamp, which I assume are fragments of the same picture.

It’s better (and more common) to describe these NAL units as “slices" rather 
than “fragments”.  (The word “fragment” is usually used to describe parts of a 
single NAL unit that are transmitted using more than one RTP packet.  As I 
noted earlier, the LIVE555 code automatically handles RTP 
fragmentation/defragmentation.  Your use of the word “fragment” was confusing.)


> However, I'm having trouble figuring out how to recognize if the NAL units 
> are [slices] and how to merge them before sending them to the decoder.

Basically, you’re asking how to decode and render H.265 (aka. HEVC) video.  
This has nothing to with the LIVE555 code (as it does not include any video 
decoding or encoding functionality), and thus is outside the scope of this 
mailing list.  However, you might wish to take a look at the VLC source code.  
VLC uses the LIVE555 libraries to receive H.265 (and H.264) video over RTP, and 
thus will also receive one NAL slice at a time (when a video frame consists of 
multiple ’slice’ NAL units).  So, the VLC code has figured out how to decode 
and render these slices.


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


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