Most of BBC Radio programmes to become downloadable...

Vangelis forthnet northmedia1 at
Mon Jul 20 16:47:16 PDT 2015

On Mon Jul 20 17:41:10 BST 2015, SquarePenguin wrote:

> I downloaded an episode of Infinite Monkey Cage
> and it was 70MB for 27 min and 51 seconds.

Yes, you are right! I did my own searching on the net,
since I can't try the app myself, and found many references,
among which this:

So it's ~ 140MB/hour; but they promise to offer
smaller files later in the year:

The high bitrates launched initially are to coincide with Proms 2015 

>  An uneducated guess is that the bit rate would
> therefore probably be 320kbps or thereabouts.

Spot-on! (see my analysis below...)

On Mon Jul 20 17:13:45 BST 2015, I wrote:

> can you perform some kind of URL sniffing
> on your tablet/smartphone to possibly reveal
> the download URLs template for those new
> (drm'd) audio downloads?
> I'd like to take a look at their specs,

Well, I couldn't "lay my hands" on the iOS app,
but I did manage to grab a copy of the Android app
and store it onto my Win32 laptop via:

(thank you !)

Then I unzipped the .apk file and probed its contents...
Lots of interesting stuff to be found inside,
among which a working/valid NitroAPI key the
app uses to gain access to the new Nitro indexing database...

 Also, by loading the following URL in your desktop browser
you can get a quick glimpse of the app's GUI!

But what I was after was the URLs employed for the DRM'd downloads
- as it turns out, on Android devices they use a new type of "mediaset"
called "android-download-high"; the actual URL tempate is of the format:[vpid]/format/json/mediaset/android-download-high/proto/http

which yields a JSON file; [vpid] is the actual "version PID" string that
corresponds to a radio show's PID string.
For simplicity, I will substitute the above URL with a simpler one,[vpid]

which produces the same data, but in XML format.
Today's episode of TIMC is found at
reveals that (for "Original" version) vpid=b062jwx6
(when loaded from a UK IP) reveals:

<media bitrate="320" encoding="aac" expires="2015-08-19T16:00:00Z" 
kind="audio" media_file_size="1817" 
priority="10" protocol="http" supplier="mf_akamai_uk_smooth_notok" 

where you can see the indicated bitrate is indeed:
media bitrate="320"

Noteworthy is the "connection href" URL;
this does not point to a standalone DRM'd MP4 file,
but rather to a "Smooth Streaming" manifest file.
"Smooth Streaming" is a method of chunked delivery
over HTTP, initially developed by Microsoft to be
used by their proprietary Silverlight browser plugin.
to
"playready" in the URL denotes the type of DRM
encryption used (

If you download the manifest file onto disk
and open it with a text editor,
you can plainly see the file's specs
that I was after:
Bitrate="320000" SamplingRate="48000" Channels="2" BitsPerSample="16" 
PacketSize="4" AudioTag="255" FourCC="AACL"
plus you'll see that the actual end download
is the product of the concatenation
of 302 chunks, each lasting 6.4sec
(read more at: )


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