4K footage 4K TV USB

[Rivendell]

I have a Samsung UE60KS7000 TV (2016)

I have rendered a 5 minute MP video at 4K using MP4 H264 onto a SanDisk ultra flair USB (up to 150 MB/s read speed).

The TV recognises the file and starts to play it - the picture is awesome. However, after a few seconds it starts to stutter and then the rest of the video is a series of stutters with the sound chopping in and out.

The issue (in my non expert opinion!) appears to the be the capability of the TV to process the data from the USB and ultimately display it smoothly.

Is a USB viable for this type of work (even a good one)?

Should I use a different CODEC?

Is there a better way of getting 4K video to play on the TV at 4K? (I’m on 8Mb/s broadband, so streaming ain’t great either).

Anything else I’m missing?

 

[4wd]

With my panasonic you must use the USB3 (blue) port and a USB3 card reader, or put it on a USB3 flash drive.
It doesn't have an inbuilt card reader.

 

[Rivendell]

With my panasonic you must use the USB3 (blue) port and a USB3 card reader, or put it on a USB3 flash drive.
It doesn't have an inbuilt card reader.

Thank you. However, the USB is a flash drive. It’s USB3 and so is the TV port.

 

[ac0j]

Can the TV process any other source at that high of resolution? If so, I lean more towards the USB port in the TV not actually being what it is described to be.

 

[Rivendell]

Sorry - my mistake. The port is USB2, which could explain it. However, the TV manual says that MP4 files at 4K H264 are supported up to 60 FPS and 60 Mbps bitrate. USB 3 into a USB 2 socket shouldn’t make a difference (although I know it will default to the USB 2 speed). I’m wondering whether I should hook up a fast SSD external hard drive. Tips very welcome!

 

[Kilrah]

You probably jsut exported at too high a bitrate.

I’m wondering whether I should hook up a fast SSD external hard drive.

It won't make a difference if your port is USB2...

 

[Rivendell]

Thanks Kilrah. I have tried a USB 3.0 flash, a ‘normal’ external HDD and my MP micro SD (SanDisk Ultra Pro) through a USB 2.0 reader and the ‘best’ playback is through the USB 3.0. My kinda thought was that the better quality input device resulted in the best output and therefore an even faster device (e.g. SSD) would be better still and get the max potential out of the connection.

You’re saying there will be a bottleneck regardless, I suppose the follow on question is whether peope’s experience with USB 2.0 sockets is the same as mine? My video is 4:05 long and around 5.3GB. If so, and there’s no way around the bottleneck, it would seem it’s 1080 rendering for me, which is a great shame because the TV is 4K QLED display

 

[Rivendell]

You probably jsut exported at too high a bitrate.


It won't make a difference if your port is USB2...

Kilrah,

I’ve fixed it, thanks to your advice. On looking at the render settings the output quality was 4K H264 80000Kbs, which is beyond the stated TV limit of 60000Kbs. So, I re-rendered at the new setting and it worked a treat. Thank you.

However, I learnt some things here.

1. MP records at max bitrate of 60Mbps so rendering at 80Mbps was a total waste of time and something I hadn’t really thought about.
2. Perhaps more significantly is the extraordinary difference in file size. 80Mbps = 5.3GB; 60Mbps = 0.9GB! A sixth of the file size. I wondered why I was using up space so quickly - bitrate v file size must have some sort of logarithmic relationship.

Thanks again The forum works!

 

[4wd]

You might try rendering at 2.7K or the 1440p setting which youtube can play at.
The 1440p apparently allows higher bitrate when played at the 1080p setting than if you uploaded 1080p to start with.
I know you aren't talking about youtube but rendering various sizes is tedious and that ^ is a sensible default which will look much better than 1080p, if not 4K rendered at lower bitrate

 

[Kilrah]

That recommendation makes no sense at all for watching on a 4K TV. Especially since as explained the issue was unrelated.

1. MP records at max bitrate of 60Mbps so rendering at 80Mbps was a total waste of time and something I hadn’t really thought about.

Well yes and no, you normally DO need to increase bitrate a bit to maintain quality of an already compressed source through a new conversion process.

BUT...

80Mbps = 5.3GB; 60Mbps = 0.9GB!

The software you used must be broken when set above 60Mbps, becasue 80 should only be 30% bigger. The value precisely tells you what space is taken by each second of video, so can't be logarithmic...

 

[Rivendell]

I’m afraid I screwed up again! My 0.9GB render was actually at 1080 and 60, rather than 4K and 60. Sausage fingers don’t help.

BUT ....

I’ve now re-rendered at 4K and 60 (triple checked settings) and it comes out at 1.5GB.

HOWEVER ...

I use Davinci Resolve 15. The 4K H264 render qualities are described as “Best”, “High”, “Medium” etc. It defaults to “Best” (where the stuttering occurs). Below these options is a drop down menu with a box which, on closer inspection, gives you the option to restrict bitrate to 80K. “80K” shows in the window however, and I (mistakenly) thought that was the bitrate it was rendering to (rather than an option to restrict to that bitrate). Having checked the properties on the 5.3GB file, the actual render bitrate was just over 180K. I entered 60K in the 80K box thinking I was reducing from 80 to 60 when I was actually reducing from 180K to 60K which makes far more sense (and describes a more Iinear relationship between bitrate and file size).

Apart from wasting no more of your time, I will now up the bitrate a bit to offset for the file compression until I reach the highest figure I can. I must say, however, I’m jiggered if I can tell the difference between the 180K and the 60K versions with the naked eye!

Every day’s a school day ...