[Icecast] Webm files written without duration in header

Sytze Visser sytze.visser at gmail.com
Wed May 1 20:06:12 UTC 2019

Hi Fred. 

Appreciate your response. 

Maybe in my explanation I have some red and green apples, but I can 
agree that my understanding is as you explained it. 😊

The point is that if I can successfully stream mp4 with H.264 and AAC 
encoding without any issues to icecast, I can then use ffmpeg to 
turn it into HLS which then solves my iOS support issue. The CPU 
cost of repackaging MP4 into HLS architecture should be minimal
because at the core it’s all H.264. No transcoding! Low CPU objective 
Additional bonus is that I already use Apach2 with icecast and 
integrating the whole lot into my existing infrastructure is easy.

My question remains
If webm/ogv is supported but mp4 not, what are the technical differences 
in how icecast handles the one and not the other? What does icecast 
manage/do for supported formats as opposed to unsupported ones?

Kind regards

On Wed, 2019-05-01 at 19:56 +0200, Sytze Visser wrote:
> I read somewhere that MP4 is not supported on icecast, which is a
> pity. I have invested a lot in an icecast based audio solution and
> want expand it with video. 

It all depends on what one means by 'MP4' (which is more a marketing
term than a technical one). AAC+ (aka 'high efficiency' AAC) works very
well on IceCast, albeit that only covers the audio side on the

> So my question is now:  
> MP4 (H.264) is a close relative of HLS (can also be H.264) which
> brings me very close to a solution.

You're mixing apples and oranges here (pun accidental). H.264 is a
content encoding, like MPEG Layer III (so-called 'MP3') or OggVorbis.
HLS OTOH is a streaming architecture, and as such is largely orthogonal
to the content encoding used. It works by segmenting the media stream
into discrete files and then distributing them via HTTP(S). The big
advantage of this approach is that standard 'garden variety' web
servers (think Apache) can be used to serve the streams, which makes it
play particularly well with CDNs, at the cost of significantly greater
complexity in the encoder and player components. No specialized
'streaming server' (such as Icecast) is required in the HLS ecosystem
at all.


| Frederick F. Gleason, Jr. |             Chief Developer             |
|                           |             Paravel Systems             |
|  An expert is a person who avoids the small errors while he sweeps  |
|  on to the grand fallacy.                                           |
|                                                                     |
|                                              -- Benjamin Stolberg   |

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