[Icecast] Higher quality narrowband streaming options

[TheDarkener]

If you do further testing with Opus, please let us know your findings.
I'm interested in this newer codec myself. I'm currently using vorbis
for my radio station (similar to yours, a no-budget Internet station)
and support for it is limited (nothing on iOS that I know of, and
Android (AFAIK with my very old Android phone) doesn't support it OOTB
(but XIAA Live Lite handles vorbis streaming wonderfully). I've looked
into having a generic (but customizable) Android/iOS radio player
developed that centers on open codecs such as Vorbis/Speex/Opus. Who's
willing to chip in with me to get it done? :) Would be really cool to
have a definitive player that we could refer people to.

- Jordan

On 08/01/2012 01:50 PM, Geoff Shang wrote:
> Hi,
>
> Up until now, I've been providing narrowband streams at 24kbps MP3.  We've 
> reluctantly been using MP3 instead of say Ogg Vorbis due to wider 
> support.
>
> But it's getting to the point where low bitrate MP3 doesn't really cut it 
> anymore.  With technologies like AACPlus out there in common usage, people 
> have come to expect better and one can hardly blame them.
>
>   So I thought I'd start a thread on low bitrate streaming in order to find 
> out what people are using and how.
>
> There seem to be two issues.  The first is which format to use and the 
> second is how to go about transcoding into said format.
>
> Right now we're using StreamTranscoderv3 to do our transcoding.  It can 
> turn around our broadband stream as a narrowband stream without any 
> intervention.  I've successfully used it to turn around streams as MP3 and 
> Ogg Vorbis.  It's also meant to support AAC and AACPlus, but I've not 
> managed to figure out how to enable this under Linux or how I would 
> particularly get it to be able to do AACPlus.
>
> I considered going so far as to try Nullsoft's sc_trans v2 to encode 
> AACPlus, but it seems it cannot connect to an existing stream and relay 
> it, it can only have a stream connect to it.  I don't see how I can get 
> our existing Icecast stream to be relayed to sc_trans as Icecast does not 
> do push relaying, so this option would appear to be out.
>
> I also took a brief look at Liquid Soap for doing this.  It would appear 
> that it can, but it looks like a lot of work to deploy for a relatively 
> simple task.  Still, I'd consider it if it will do the job.
>
> This of course leads to the broader question of which format to use.  For 
> us, the chief concern is device support.  While a lot of people get around 
> this issue by writing their own apps with built-in decoders, this isn't a 
> direction I'd particularly want to go in unless there's something out 
> there that's fairly generic and can be easily customisable.  Our station 
> is a volunteer outfit with no budget, so my strong preference would be for 
> us to use a natively supported format so that it "just works".
>
> As mentioned, I'm looking to depricate MP3.   It's really not possible to 
> get 44.1 kHz MP3 under 56 kbps, and that only in mono.  This isn't really 
> "narrow" enough for my tastes.
>
> I'm not a big expert on AAC, but it seems to me that plain AAC (no 
> "plus") doesn't really offer much over and above MP3.   Certainly, samples 
> I've heard of 56 kbps AAC streams at 44.1 kHz stereo are rolled off to 5 
> kHz audio, making it sound worse than MP3 at the same rate using 22.05 kHz 
> samples.   But there's so many AAC parameters that I'm by no means an 
> expert on this.
>
> From the little I've seen, the favoured option for lower bitrate streaming 
> seems to be AACPlus.  And it's not surprising given how good it sounds. 
> I'm not so sure about device support though, and encoding it is a bit of 
> an issue (see above).  There is libaacplus, but streamTranscoderv3 doesn't 
> *appear* to support it.  I think Liquid Soap might though.  There's also 
> something called AACPlusEnc but I can't seem to get to its home page.
>
> While we're considering non-free options, Windows Media Audio would seem 
> to be out due to the desire to encode under Linux, and people seem to be 
> moving away from Real Audio.
>
> Of course, I'd prefer to use something open if people can actually listen 
> to it.  There would appear to be the following options:
>
> Ogg Vorbis: Using oggenc with libvorbis 20100325 (1.3.1) at quality -1 
> with a  44.1 kHz mono source, I can get the bit rate down to about 34 
> kbps.  Stereo is more like 40 kbps.  It actually sounds pretty good. 
> Maybe if I took it down to 32 kHz 
> it would go a little ower, or perhaps the quality -2 mode that at least 
> was available in the aoTuV encoder would get it lower with perhaps a 
> little more quality loss.  I've not actually tried lower bitrate stuff in 
> either vorbis encoder for some time.
>
> Encoding Ogg Vorbis won't present any problems.  My concern about Ogg 
> Vorbis is support in mobile devices.  I know that iOS devices don't 
> support it natively.  Do any stream players for iOS support it, like say 
> Tunein Radio?  I believe Android devices do.  Don't know about other 
> devices used on the go.
>
> The other open option I can think of is Opus.  I've not put it through its 
> paces, I really should.  But it aims at least to be good for this sort of 
> thing.  But I'm really not at all sure what software support is like yet, 
> either for encoding or listening.  Anyone know?
>
> Are there any other options that are worth looking at?
>
> Geoff.
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-- 
Jordan (PGP: 0xDA470FF8)