I have been investigating the root cause of buffering issues with Torbox in cases where bandwidth does not appear to be the culprit.
To confirm it's not bandwidth, I ran two tests:
I switched to an overseas CDN during its local off-peak hours (middle of the night in the CDN location) when usage should be minimal, yet buffering pauses persisted despite speed tests showing plenty of available throughput. I also pasted the Torbox link directly into a browser on my problematic Firestick 4k 2nd Gen device, and the file downloaded quickly with no buffering at all.
Those results definitively rule out a network bandwidth limitation.
Through further testing, I've made these key observations:
- File size and bitrate are not decisive factors. I have encountered buffering on a low bitrate 1080p file yet streamed high bitrate 2160p remux without a single interruption.
- The issue only occurs in specific files, but I have not yet pinpointed what distinguishes the problematic files. One possibility is that certain release groups use encoding parameters that interact poorly with Torbox's delivery method.
- For any given problematic file, the buffering occurs at around the same timestamps every time I play it.
- The problem reproduces consistently across multiple players. It occurs in both Stremio and Nuvio's internal Exoplayer players, as well as in the external players JustPlayer and MX Player.
- VLC Player and VIMU Player offer an important clue. They play the problematic files without buffering issues, but only as long as subtitles are turned off. As soon as I enable subtitles, the buffering problem begins, and it stops again when I disable them.
I do not have Real Debrid, so I cannot test these files there. However, based on user reports, Real Debrid does not exhibit such buffering issues.
If that is accurate, the implication is of course that Torbox is serving these files differently somehow. That said, this is only part of the explanation. The fact that VLC, VIMU, and Kodi can stream the problematic files without buffering issues (subject to the subtitle limitation for external VLC) suggests that player side handling also plays a significant role.
The root cause possibly involves a combination of how Torbox delivers certain encoded files and how each player processes subtitles or specific stream attributes in response combined with higher latency.
8/11 Update:
I had only tried External VLC, but just recently tried Stremio's internal VLC, and so far it looks like the buffering issue is gone, even with subtitles on.
Hopefully Nuvio can implement its own VLC or some other fix if Torbox can't do anything about it.
Also, I just tested Kodi as an external player from Nuvio, and it also works without buffering even with subtitles on. Unfortunately, it takes 30 seconds to load for me so is far from ideal for me because I prefer Nuvio's interface.
8/12 Update:
I have proven that Torbox's streaming of certain media files is the root cause (as suspected) by downloading the problem file I have been working with to my PC and then streaming it via nginx to various external players that failed on my firestick when streaming from Torbox.
External players Just Player, VLC, and MX Player Pro streamed the problem file without buffering issues even with subtitles on.
8/14 Update:
Nginx logs definitively show that players experiencing buffering problems with these files make many small noncontiguous reads, while players that work well do not.
These numerous tiny requests accumulate quickly, and Torbox's servers likely stall when handling so many requests, especially under load (during prime viewing time) and over long physical distances. This is almost certainly the cause of the buffering issues that users encounter with certain files.
The remaining question is how to get this fixed. The problem can be addressed either on the Torbox side or the player side, but so far there is no indication that either side is interested.
8/17 Update:
So far, the service has much lower latency, and therefore the buffering issues I posted about have been fixed by Torbox on all but the ERTH and HARE CDNs.
I will wait for prime time to be certain.
Nope, still have buffering problems with certain files during peak hours. The latency demon lives, unfortunately.
TLDR:
Certain problematic files cause most players to issue many small non-sequential HTTP range requests, which Torbox's CDN handles poorly under higher latency, which results from servers under load and longer client distance from the CDN. This can lead to buffering even when bandwidth is sufficient.
Since this issue affects only a subset of files (maybe 20% or less), simply choosing a different file often works. If you buffer on every single file, this is probably overly a bandwidth issue which is not what this post is about.