on 15-02-2013 17:14
However some (claimed) 1080p videos absolutely refuse to load at a high bit rate even though I can simultaneously stream another video at 60mb/s. The videos that have issues often stream at a lower 2mb/s, 4mb/s, 6mb/s or sometimes up to 20mb/s for a brief period then lower.
Yes! This is exactly what I have noticed when streaming 720p videos from twitch.tv. I monitor my broadband activity closely while watching these stream, and I too have notice the same pattern. It will stream at the required 2000/3000kbps that the video is encoded at, for maybe a second or 2, and then it will suddenly drop to 200/'300kbps, and thats when the buffering occures. Then it will shoot back, and continue to stream fine for another few seconds before dropping again.
There must be something on VM network that is causing this sporadic activity...
But thank you for pointing this out as I thought I was the only person who noticed this.
15-02-2013 18:46 - edited 15-02-2013 18:46
ye same 100mb connection and cant even watch streams @ twitch.tv. This broadband is a misunderstanding
on 15-02-2013 21:37
same here, people on the phones dont even know this problem exists so they dont log or do anything.
We are all doomed.
on 15-02-2013 23:52
Some video streaming services operate on the basis of serving up the first part of a video (e.g. the first 30 seconds) at a higher speed then drop down to the minimum requirement for the bitrate of the stream.
This is a good way to alleviate buffering issues for a vast majority of people on high latency or unreliable connections, rather than just-in-time delivery which requires good latency and low jitter in order to operate reliably.
The reason is that most people only watch the first few seconds of most videos and then change their mind and watch something else. So this is a good strategy when dealing with most common low-bit rate videos (240, 360, 480p).
On youtube 360 is often a common default and 480 is often selected when you maximise the youtube video. However 720p and 1080p have to be manually selected.
So this is probably another reason why they asume if you select 720p or 1080p that you're serious about watching the whole of the video and the bit rate reflects that.
Btw, some videos marked as 1080p seem not to actually be 1920x1080, which seems to cause the delivery to act at a lower rate and cause an issue for buffering.
Bit-rate cycling (on-off) is another commonly strategy to give blasts of data at high rate but non-continuously.
There is undoubtedly a relation between speed of video delivery and cache location also as cache misses will require loading from a secondary or other cache further away from the users DNS.
I've seen people wonder here why when using a VPN tunnel it alleviates the streaming issue. It's because youtube employ a DNS lookup for the video server assignment. Also if you tunnel through to America then you'll likely get a video server on the google backbone.
I use a lot of different streaming services including veehd, youtube, hulu, bbc iplayer and at least a dozen other servers on a weekly basis. I'm using divx and flash daily and am beta testing the html5 youtube service.
Buffering problems are a complex end-to-end issue though, with most limitations given by the video server/service itself rather than the network. Of course if you have high levels of unrecoverable packet loss (un-corrected by the modem hardware) or jitter on a just-in-time stream that is not going to help performance at all.
16-02-2013 00:03 - edited 16-02-2013 00:05
I've read here people saying that VM are caching youtube/flash and wondering why, or asking for it to be removed. That idea is laughable in terms of a workable video strategy.
We and VM don't have a choice, since it's part and parcel of YouTube's video architecture. The only choice they have is whether to host a cache within their network or use ones outside their network. Having it inside their network should improve performance as we have lower latency within VM network than without.
YouTube uses caches, I would have thought that a no-brainer given how much volume of video they serve. Everyone and everything uses caches these days. They simply wouldn't be able to support the number of users that they do without it.
YouTubes cache architecture reverse engineered:
Answers to why my video streaming bit rate goes up and down (on/off strategy). Why a video streams fast for the first part of the video then slower. And other answers.
You will probably recognise some of the streaming strategies from the pictures, even if you don't read the paper.
on 16-02-2013 10:10
according to that last article, Flash based videos don't use the ON-OFF strategy, which puts us back to square 1. youtube and twitch.tv both use flash based video, so whats going on?
on 16-02-2013 21:13
16-02-2013 22:34 - edited 16-02-2013 22:37
however I'm starting to wonder if this national Youtube buffering issue is returning to my connection as I have a high utilisation fault ref
I question how good their tests are. It's clearly back. Just hope it's sorted as soon as humanly possible
on 16-02-2013 22:38
This evening You tube is useless. Buffering, buffering buffering.
I am not in an area of high utilisation as Virgin call it, or more precisely to the general public, an area of under investment whilst taking on more customers.
So what it happening. Failing to play a basic video on a 120Mb connection is awful.
It's nice getting letters through the door telling me 80% of my neighbourhood is connected and I should to.. actually not it's not - and I wish they would just bloody stop sending me junk mail with offers cheaper than I am paying now. I am only 2 months into my new contract and they never even gave me the money off it said!.
on 17-02-2013 11:42
Try the 1080p and 720p test videos here: