I have a movie file with 4 Mbps quality. Plex and Tautulli both shows me required bandwidth of 20Mbps when on Android TV (Plex app), 25Mbps when on PC. Everything is direct play and no subs are burning on both players.
And it lags horribly. The file is around 3.3 GB, the length is 1h 54m. So it’s around 0.5MBytes per second, and my speed is around 1.8MBytes.
What could be the problem?
That 4 Mbps is the average for the file. Most files are not made with what is called constant bitrate, it is usually variable meaning it can fluctuate. In some files, this can fluctuate hugely from the average. PMS will analyze your file when you add it to your library to determine how bad these fluctuations are and what bandwidth is needed to avoid buffering. This can also vary slightly depending on the client, that’s why you see different values. There’s no way to fix this except to reencode your video and set limits on how high these fluctuations can go.
And it can go up to 25Mbps for a 720p, HEVC, 3.3 GB movie? And why would it show different values on different clients, all using direct play? It was 20 on Plex for Android, ~22 for Plex in Kodi and 25 for PC. Quite a jump TBH.
With that bandwidth the whole movie can be downloaded as a file in 18 minutes, while it’s length is almost two hours.
The variation really could go that bad?
The requirement is just that, what is required to prevent buffering, not what the actual file is. The requirement changes because clients have different memory sizes available to hold the video. Think of it like a highway. You don’t need all those lanes all the time, but during rush hour, when there is a peak in the flow, you do need that capacity. The different values for clients are like different configurations of the highway that affect how many vehicles it can get through.
As for the actual bitrate of the video, I’ve seen some videos with peaks 10 times higher than the average, some even higher.
Strange that device, which has the most memory and best connection needs the most bandwidth.
Anyways, thanks a lot for your help! Now I understand how it works and why sometimes it lags, even though it looks like it shouldn’t.
It’s not the system memory. It’s the memory available to the video player embedded into each specific client. The overall system memory has very little impact on the video player.
So RAM/VRAM/HDD won’t play any role in this? Basically it’s a predefined limit per device?
Correct. The only exception is Plex Media Player, which can utilize more memory but only while direct playing.
Well the largest required bandwidth was for the Windows desktop version of the Plex Media Player, direct play.
Anyways, I’m getting out of topic here. Thanks for your clarification!
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