320kbps radio audio available via MPEG-DASH

[Vangelis forthnet]

On Fri Jan 8 17:25:13 GMT 2016, Simon Nash wrote:

> The commit note has this comment:
> Note that MPEG-DASH streams cannot be
> streamed to stdout.
>
> What is the reason for this?

You'd have to post in the Support Forum to
get a definitive answer from dinkypumpkin...

Based on my MPEG-DASH experiments some time ago,
I can add the following to the discussion:

An MPEG-DASH (audio) stream is a succession of fragments
which initially constituted an MP4 file.
The first fragment is called "initialisation" fragment,
in essence is the bare moov atom of the original wholesome MP4 file.
Placing the moov atom first makes the file streamable...
The following fragments belong to the mdat atom of the MP4 file.

As said already, I have not yet had the time to probe the
MPEG-DASH code, what I did in my own experiments was to parse
manually the manifest (media presentation description, .mpd),
download the init fragment and then batch download a number of
the mdat fragments.
Then I would simply concatenate files using this Linux-y command
in my MSYS2 compiler (I am on Windows x86):

cat init.dash $(ls -vx mdat_frag-*.m4s) > iso6dash.mp4

The concatenated file is an MP4 file, but of the iso6 (dash) brand
(easily inspected with MediaInfo). I have found out that on Windows
MPC-HC, MPC-BE, VLC 2.1.5/2.2.2 can play back fine this
concatenated iso6 audio MP4 file...
Maybe GiP 2.95dev is doing a similar thing, i.e. first download all
the fragments and then do the concatenation, in which case you
can see that no streaming is possible - I honestly do not know,
I haven't studied the code (and it's not certain I'll understand it
completely if I do... :-( ) . If it does successive concatenation,
then the partial download should be streamable in VLC...

A somewhat related info is that VLC 3.0.0, currently in the
Nightly stage, does come with support for MPEG-DASH streams;
the repo for win32 is at:
http://nightlies.videolan.org/build/win32/last/
You just have to find the manifest URL for a BBC radio show
(see e.g. 
http://lists.infradead.org/pipermail/get_iplayer/2016-January/008554.html )
and simply input the full .mpd URI (href="...) to VLC 3 via
Media -> Open Network Stream
You can even record the stream, but of course in "real" time...

(If you are also asking about the VOD (TV) dash streams,
these cannot be streamed for other reasons, major being
that GiP first downloads separately the audio stream and then
the video stream, which, in its current format, is not processible
by FFMpeg or playable by VLC...).

Regards,
V.