[Icecast] Intro & Chrome v.

Philipp Schafft phschafft at de.loewenfelsen.net
Thu Apr 19 05:44:33 UTC 2018

Good morning,

On Wed, 2018-04-18 at 22:17 -0700, Brad Isbell wrote:
> There should be no issue with the varying bit rate.  For an MP3
> stream, you
> can change bit rates mid-stream all you want as long as you keep the
> sample
> rate and channel counts the same.

This is true for many codecs. However we have seen some really bad
implementations for MP3 that required all encoder parameters to be
time-invariant. I don't want to say that it's the problem. Just want to
say it's worth to have a look at this as well.

> If you check chrome://media-internals, you'll see that you're getting
> a PIPELINE_ERROR_DECODE.  Since Chrome v64, it has been a lot more
> picky
> about the streams it accepts.

> I suspect that Icecast is simply dumping the buffer for the file out
> to the
> client, and then needle-dropping into the middle of the live MP3
> stream
> without re-syncing to a frame boundary first.  (Someone more familiar
> with
> the Icecast internals could probably answer that in detail.)

For all supported codecs Icecast2 does proper re-syncing and all other
necessary steps for a correct transition. However as MP3 is not a
supported codec Icecast2 uses the 'generic' handler. Which basically
does what you said above.

> I suspect that Chrome isn't happy about this, doesn't bother to
> re-sync to the stream itself, and throws this error.

Then it would be Chrome's bug. The syncwords exist for a reason: to make
broken streams recoverable. Bit flipping errors aren't uncommon. And MP3
can handle them. There is no real excuse why not to handle them. More
true if it worked in older versions of the same software.

But this is just a guess at this point.

Generally speaking: Players improved over the last decade. Even MP3

> On Wed, Apr 18, 2018 at 8:06 AM, Oskar Vilkevuori
> <oskar.vilkevuori at ovt.fi>
> wrote:
> > I have done my best to set up the intro to match the live stream.
> >
> >
> >  - intro is 256 kbits/s 48 kHz ISO-MPEG2 L3
> >  - live is 256 kbits/s 48 kHz ISO-MPEG2 L3
> >
> >
> >  - live is 128 kBits/s 48 kHz, possible ISO-MPEG2 L3
> >  - there is no intro

With best regards,

Philipp Schafft (CEO/Geschäftsführer) 
Telephon: +49.3535 490 17 92

Löwenfelsen UG (haftungsbeschränkt)     Registration number:
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