HEVC what settings are needed for compatibility ? (file appending)

[Selur]

Thinking about appending 'randomly' encoded HEVC streams, I was wondering what settings need to be compatible to append h.265 raw files without running into problems? (encodings would be done by different software and hardware encoders)

Had some thoughts about it:

• resolution -> yes
• frame rate -> yes, unless the output is allowed to be vfr and the time codes are adjusted during muxing into a container: yes
• bit depth -> yes
• color sampling -> yes
• vui related settings -> yes (at least if the color representation should stay the same)
• loop filter -> probably not
• sao related settings -> probably not
• profile/level/tier settings -> using the highest profile/level/tier settings of the all clips should be fine
• scene change related settings -> should matter
• gop size related settings -> min/max gop size shouldn't matter, whether 'open'- or 'close'-gop is used probably does
• weighted p-frame prediction -> probably yes
• max ref frames -> probably not (as long as profile/level/tier restrictions are not hurt by it)
• max number of consecutive b-frames -> probably not (as long as profile/level/tier restrictions are not hurt by it)
• b-frame frequency boots and decision settings -> probably not (as long as profile/level/tier restrictions are not hurt by it)
• b-pyramid usage: probably yes
• weighted b-frames: probably yes
• interlacing: yes (mixing progressive and interlaced content always is a bad idea)
• quad tree related settings like wpp, lossless cu, ... : probably yes
• rate control and motion prediction settings: probably not

-> if someone has some additional thoughts about it, please post.

Also once it is clear which settings need to be equal for streams that should be appended, the next question is how to check how these settings are set - given a lot of raw samples ? (preferably through the command line, to automate things)
Mediainfo, ffprobe, doe not seem to give all needed settings.

So if anyone has some useful thoughts please share.

Cu Selur

[sneaker]

I assume you are talking about MKV and MP4 containers.

scene change related settings -> should matter

What are "scene change related settings"?

whether 'open'- or 'close'-gop is used probably does

I don't think so. (as long as you cut correctly)

max number of consecutive frames -> probably not (as long as profile/level/tier restrictions are not hurt by it)

What do you mean? Every movie is a "number of consecutive frames".

b-frame frequency boots and decision settings -> probably not (as long as profile/level/tier restrictions are not hurt by it)

Are there any HEVC profile/level/tiers with b frame limits in the first place? Maybe "still picture"?

max ref frames -> probably not (as long as profile/level/tier restrictions are not hurt by it

b-pyramid usage: probably yes

Isn't the DPB size part of the headers? I think appending should be possible but headers should be to max value. But mixing b-pyramid with non b-pyramid should be possible as long as those headers are not exceeded by any part.

interlacing: yes (mixing progressive and interlaced content always is a bad idea)

HEVC interlaced coding is different than AVC. I think mixing should in theory be possible because it's a per frame flag but it's really asking for trouble. Players like MPC-HC or VLC cannot even deal correctly with interlaced HEVC at all at this point.

[Selur]

I assume you are talking about MKV and MP4 containers.

No raw content.

What do you mean? Every movie is a "number of consecutive frames".

'frames' should have been 'b-frames'

[sneaker]

For raw content it might be possible to allow mixing of levels as long as all PPS->SPS->VPS pointing is done correctly with increasing ids. I don't think it's possible to set those using e.g. x265cli, though, in case you have that in mind. Not really sure if it matters in practice. I mean, no one plays raw content anyways except for a short preview while encoding? No idea what you are aiming for in the end. Not even sure ids are not even required to change.
Maybe others know more, I'm not an expert.

[Selur]

I think the main gain from knowing how compatible streams need to look like would be that once we know that, can analyse stream for those settings and we know how to create compatible streams writing a smart cutting/encoding tool would easy.