Podcast sample rate

michael norman michaeltnorman at gmail.com
Wed Jul 26 05:37:45 PDT 2017

On 26/07/17 12:36, RS wrote:
>> Sent: Thursday, July 20, 2017 12:56  I wrote
> To: get_iplayer at lists.infradead.org
> Subject: Re: Podcast sample rate
>> I wish the BBC would think more about backwards compatibility of AAC. 
>> There is no problem with software players.  HTML5 and recent versions 
>> of VLC fully support HE-AAC v2 with LC (Low Complexity), SBR (Spectral 
>> Band Replication) and PS (Parametric Stereo).  The problem is with 
>> hardware players.
>> I am not alone in this list in having had difficulties playing AAC-LC 
>> at all.  When trying to find hardware players which support SBR and PS 
>> the problem gets worse.

I have always used hardware players by which I assume you mean portable 
players to listen to music.  Those used to be called mp3 players 
culminating in the iPOD I suppose.  Nowadays I still do that and having 
used various Cowon models in the past I now use a Fii0 X1.  That one 
costs around £99 plus memory card.  Nowadays I imagine most people use 
smartphones as general media devices and the market such as it is for 
"mp3 players" has moved upmarket into its own niche.  My Fiio device is 
one of the cheapest options in that market.  I only use it to play cds 
ripped into flac or ogg and a very few mp3  I imagine if I put a some 
radio programmes from GIP on it that it "should" play them, I haven't 
tried that.  Whether cheaper players like some on the Sandisk ones that 
will do that I don't know.  Neither do I know how smartphones perform in 
this area for the simple reason that I don't have one.

The bigger question I suppose is how many devices can the BBC be 
expected to support on for their content.  Plus given that all of this 
is a moving target who if anybody could produce a list of which BBC 
modes work on which players ?  Or have I missed your point ?
> Obviously what I would like the BBC to do is off topic.  Even so, I hope 
> I will be forgiven for saying that I would like to see a move towards at 
> least 128kbit/s stereo audio in preference to adding SBR.

I only have a vague idea of what SBR or even VBR means. is that an MP3 
thing ? I only use MP3 when I can't get the content any other way.
> What I would like get_iplayer to do is to include in the documentation a 
> warning of the perils of SBR for players which do not support it and to 
> include in the table in
> https://github.com/get-iplayer/get_iplayer/wiki/modesref
> an indication of which modes use SBR and which do not.

A question for the GIP developers ?
> Is the table up to date?  For HVF 50fps modes it shows the audio bit 
> rate as 128kbit/s or 320kbit/s and for HVF 25fps modes other than HVFlow 
> it shows the audio bit rate as 96kbit/s or 320kbit/s.  I have not used 
> the 50fps modes but I have occasionally used HVFxsd.  I have not seen 
> 320kbit/s audio. Which programmes use it?

See last coment.
> Is the radio table up to date?  I thought I had seen somewhere that 
> there had been a relaxation of the 96kbit/s maximum bit rate when 
> listening abroad.  I can't find anything about it on the BBC's website.  
> This page
> https://www.bbc.co.uk/iplayer/help/Mobile_abroad
> tells me under the heading, "Can I listen to radio abroad?"
> "You can also listen to BBC radio outside the UK from a desktop computer 
> at www.bbc.co.uk/radio."
> There is no mention of bit rate.  If I go to that page in Firefox it 
> does indeed play the programme I select, but it does not offer me a 
> choice of bit rates, but automatically plays at 320kbit/s.  I have not 
> tried doing it abroad.
> Interestingly that 320kbit/s bit rate means the radio iPlayer offers the 
> highest bit rate of any mode of delivering radio programmes.  Television 
> is the poor relation in comparison.  Many broadcast programmes include a 
> 256kbit/s AC3 stream, but for most modes the iPlayer does not offer 
> anything better than 96kbit/s stereo.

Listening abroad is not an issue for me, being in UK

For my use radio downloads are now 320kbits by default which suits me 
given thar I have the bandwidth, I assume I could specify a different 
mode if I needed to.

As you say if you listen to radio iPlayer via Firefox or any other 
browser it doesn't offer a choice of bitrates.  I think it should but 
maybe that's one for the BBC.

Personally I'd like to see tv programmes offer the highest quality audio 
as per radio, again one for the BBC ?


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