Why does watching avi from wireless cause buffering on every action scene?

[sakuya_su]

This is the problem I'm facing, some of you may remember that I asked about CBR before, its related to that also.

I have now encoded my files to 320x240 at 650Kbps CBR with 96Kbps CBR Audio, now my wireless is 802.11b and my bandwidth test (done with a sniffer) shows it has a stable bandwidth of about 900Kbps.

the problem now is by using the above setting, I should be able to watch the entire file without buffering? correct? it does nto seem to be the case.

anyway, the Player I use has a buffer of 1.6mb and a "Buffer at underrun" of 95% (actually can some one please explain what that means with 95%?)

Thanks very much in advanced!

[sakuya_su]

BTW, CBR Video was done using 2 pass lavc and the vrc_maximum = 650 in MEncoder

[vitualis]

What device are you playing with? A Pocket PC?

Your sustained bandwidth probably is not as high as you think it is.

Regards.

[sakuya_su]

yeah its a pocket pc.

I did an 4mb file test with a traffic analyser on the server side and the result showed the bandwidth as 120kb/sec, which i think is 960Kbps?

[greymalkin]

this is really too close for comfort to expect a reliable stream especially with wireless...you maybe getting a 900kbps throughput but your actual efficiency [actual information / (info. + overhead)] might be such that you are teetering above and below the required data rate for the stream. you are sending the video stream but it's stuffed into a packet along with other information to tell the network what address it's going to along with error checking bits and instructions for other networking layers as it makes it's way to your media player. Assuming this packet was 70% your information, then you would be gettin an actual data rate of 672....which will fluctuate given the nature of the wireless beast...

i don't suppose there is an upgradeable wireless card in that thing?? :P

[edDV]

Connect with wires (direct Ethernet) if it works then debug your wireless assumptions. If it still doesn't work, then the problem is deeper.

[RabidDog]

double or treble what you require and thats your baseline on a wireless connection eg you need 1000 so get 3000

[sakuya_su]

haha

thanks for all the help, I guess i'll have to wait for a Pocket PC with 802.11g then lol XD

[vitualis]

You have to remember that Pocket PCs do not have a particularly fast radio on sustained throughput. Not sure if this is a design issue or an OS issue, or if they are just hardwired to be frugal on power consumption.

I can play XviD/DviX AVI files on my Pocket PCs over WiFi, but I usually encode them especially for the device. You can get away with much lower bitrates and still have excellent quality on the Pocket PC screen.

Regards.

[sakuya_su]

can you tell me what quality you use?

the one I use currently is:
320x240 at 650Kbps Vid and 96Kbps Audio

[vitualis]

XviD - single pass - target quantisiser = 3

Audio - 128 kbit/s

Looks okay to me on a Pocket PC. Your mileage may vary.

Regards.

[sakuya_su]

Thanks, i'll give that a go