What is the source of files downloaded by GiP?

[Jim web]

Not directly a get_iplayer matter, but may be of interest to comment...

In article
<CAPZzCnO+1ARuveTv7kXAXiRmSywALRyDf-w5-WCBWKtLXu+NUg at mail.gmail.com>, CJB
<chrisjbrady at gmail.com> wrote:
> As the truncation issues pertain - the last Cabin Pressure was the
> latest - I was wondering exactly where the programmes offered via
> iPlayer and/or downloaded by GiP are actually sourced from.

> It appears to me that the Beeb uses a capping system to record
> programmes for iPlayer as they are being aired. That is they record
> programmes off air - as they are being transmitted - much like the pubic
> might do with a programmable VCR.

If you look at
http://www.audiomisc.co.uk/BBC/AudioFactory/AudioFactory.html
you can see an outline view of the current systems.

All of this is AIUI...

The input feeds come from the standard distribution for TX. In effect what
*goes to the transmitters*. I can't comment on the input format for video.
But radio comes in as 48k/24bit stereo lpcm which is the internal
distribution standard.

The input end servers 'record' the streams as effectively a continuous set
of data so far as an 'editing' is concerned.

> This would explain the truncations - especially pertinent to radio
> programmes. If a programme was delayed due to say an extended news
> bulletin, then it would no longer be correctly capped at the scheduled
> time, and the end would indeed be truncated.

Either an automated or manual 'edit' will be done. Sometimes the edit
points will be wrong. But these days a request to fetch an item with a pid
will prompt the system to build a defined section for streaming out. These
may be cached at some level when repeat requests for the same programme are
made.

> I guess that if complaints are received that a programme has been
> truncated then the staff replace the file with a complete one kept for
> that purpose.

In effect, the edit is re-done by re-specifying the start and end times to
be applied upon request to the input data.

However, I don't work for the BBC, so am surmising from what I have been
told by some who do. I may have misunderstood.

Jim

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