Unreal Media Server

[carl669]

is there any way to set the initial buffer time in either the client or the server?

I'm streaming a couple clips which begin playback very quickly on the client side (within 2-4s), but the problem is, they chew through the buffer and constantly rebuffer.

Is there any way to set a hard buffer of 10 or 15s?

[Admin]

If you're streaming Live media (camera, TV, mic, etc) configure your source to work in "buffered mode". Also you may consider choosing lower bitrates for your streams.

[carl669]

actually, this is for pre-recorded content.

i've messed with various javascript timers to try to force the initial buffer, but none of it has worked.

any other ideas?

[Admin]

You cannot change buffer size in file-streaming mode.
BTE, what is your upload speed, what files are you trying to stream - MPEG-1/2, MPEG-4, WMV? If you try to stream, for example, MPEG-2 file over 386Kbps DSL buffering will not help you much.

[carl669]

I'm uploading on a T1 (1.5 Mbps).

I'm streaming mpeg4 files. the average bitrate of the files is about 800 kbps.

[Abraham Y. Chen]

The transmission medium that I am using is capable of over 70 Mbps thorughput. The video clips are about 3 minutes long each and I play them back in continuous cycles. When I stream one or two video clips, each appears to be able to buffer plenty of material before starts to play. The remaining steady state buffering can stay ahead and finishes nearly ten seconds before the playback completes. As I load up the system with more clients (up to six), every client begins to buffer much less during the initial phase. Consequently, the playback has to pause in the middle of the clip for rebuffering. It seems that the initial buffering in the client is set up with a finite time interval, so that the amount that can be buffered is in inverse proportion to available bandwidth? Is there any way to make it more adaptive to the available bandwidth, or at least force it to take a little longer time to do the initial buffering?

Abe (2007-03-16, 17:45)

[Admin]

Abe,

[Abraham Y. Chen]

Somehow, I did not get the eMail notice when you replied. I just thought about checking the thread and saw your comment.
Your comment makes sense. However, my report is based on the observation through the use of a freeware, NetMeter that is intalled on both the Server and all Clients. So, I can see the UL and DL traffic on every machine in "real-time" (reported in graphic bars every second or so). When I start the first video stream, I can see that the full available (70 Mbps) is used for the initial buffering for about 10 seconds. Once this stream begins to play, its ongoing buffer-ahead drops down to around 10 - 15 Mbps. The initial buffering of the next stream peaks the Server's UL traffic to the maximum for also about 10 seconds. Then, the total ongoing buffer-ahead increases to about 20- 30 Mbps. As more and more streams are activated, the initial buffering always peaks the Server's UL to 70 Mbps for about the same amount of time while the "floor" goes up like a stair case pretty uniformly. Since the initial buffering time is always about the same while the ongoing buffer-aheads take away notable amount of bandwidth, I suspected that the amount of memory buffered initially would become smaller for new streams that are added into the same medium. This is confirmed by observing the buttom status bar once the new Client begins to play. It shows that the amount of memory stored in the Client through the initial buffering is less than the preceeding stream. Since the ongoing buffer-ahead appears to be a constant rate, the streams started latter begin to have to pause in the middle of the play to wait for re-buffering.

Your further comments and advice please.


Abe (2007-04-21, 23:49)