Initial client buffer size - what does it do?

[JohnB]

What does the value for Initial client buffer size it do and what problems are/can be caused (if any) by increasing the value to very high figures. Rasing the value dramatically seems to get around the one hour Super Downloading limit.

JohnB

[blazegmc]

hey i found this in another applian forum

By default Replay Media Catcher is set with an initial buffer time of just over 8 seconds - 8192 milliseconds. When the duration of a stream is known and this is less than 60 minutes and enable super download is selected in Settings, the buffer time is set to the duration of the stream and the stream will download all at once and fast.

In the case of NPR and some others, no duration is transmitted and so the default buffer is not adjusted.

At any time you can up the default buffer size. Here's how:


1. Select Tools > Settings and expand RTMP Download Tweaks
2. Changing the Initial Client Buffer Size setting to something like 3590000 will download just under 60 mins worth in one hit.

Last Update: 10:52 AM Tuesday, September 21, 2010

[JohnB]

The penny has dropped!!

So with a bit of a calculation I should be able to get the occasional 90 min BBC7 programs to download super fast as well.

Brilliant.

Thanks very much for taking the time to reply.

John

[blazegmc]

its ok. good luck with trying it out.

post back here and let us know how you get on because im sure theres a few people who would like to do the same thing

[Jeff Lenney]

Indeed - let us know if that does the trick for you. :)

[JohnB]

Sorry to be slow coming back to you.

Using RMC version 4.0.12.0

It seems that if RMC decides that the file to be downloaded is larger than an hour (not sure of the exact time to the second) it moves into real time downloading. To do this it downloads data in chunks, each chunk being the size of the Initial client buffer size which is measured in milli-seconds. For example the default 8192 will download 8.192 seconds of data every 8.192 seconds or thereabouts.

My original assumption was that it I set the buffer to (say) 6,000,000 (which is 1 hour 40 minutes) it would download 1hour 40 mins in one burst. Not so.
It seems that if the setting is greater than about an hour, the first download is of the first 1 hour 1 min and 15 seconds or so before pausing for about 30 mins before downloading a 30 min burst and then waiting for another 30 min before downloading yet another 30 min burst.

If I have not lost you yet it means that increasing the Initial client buffer size can reduce the download times of files of over the 1 hour limit but only by a maximum of 30 mins.
Anyone using RMC with BBC7 will know that the actual file time is always 6 mins over the program time notional time to allow for early starts and late finishes. An hour program results in a file of 66 mins, a 90 min program results in a 96 min download.

I find it irritating when using a high buffer size in order to shorten download time, to have a 66 min recording pause for half an hour after downloading the first hour before a final burst to record the last few mins of a 66 min recording. There is a similar problem for 96 min recordings with another 30 min pause at the 90 min mark.

If I am not prepared to wait for the last 5 mins or so, I can ‘cancel’ the download while it is pausing and select the option to convert the cancelled file. Sample tests today indicated that I can normally just catch the full program with a minute to spare with both the 60 min and 90 min programs.
If you do this and miss the credits or even the last few sentences of the murder mystery please don’t blame me -- I maybe already kicking myself!!

If anyone discovers a way to get around this please post - or simply that they get different results!!

JohnB