[Icecast-dev] MetaData Update for FLAC and OPUS

bn at radio42.com bn at radio42.com
Tue Aug 13 12:26:02 UTC 2019

I am using the standard Xiph.org FLAC encoder, but I couldn't find any option to update the meta-data mid-stream.
Also the FLAC spec says, that it defines VORBIS_COMMENT as the only way to transmit meta-data information.
This is the only officially supported tagging mechanism in FLAC. There may be only one VORBIS_COMMENT block in a stream.

As such, when you state, that meta data is the domain of the encoder; this seems to ignore this fact, that there is no FLAC encoder support for mid-stream title updates.
This is pretty much the same as for OGG and OPUS!
As such, please point me to the encoder option you are referring to - as you seem to have implemented mid-stream meta-data updates from a FLAC stream, which doesn't exist in the FLAC specs?!

However, for OGG you (ICEcast) implemented meta-data updates via the admin interface.
So why isn't this supported for OPUS and FLAC - as all three formats do use VORBIS_COMMENT and none of the encoders seems to support mid-stream meta-data updates.

I am sorry, but I found the answers provided not really suited to my questions.

So any further help is appreciated.
However, I will also ask the same question to the FLAC and OPUS mailing list.


-----Ursprüngliche Nachricht-----
Von: Philipp Schafft <phschafft at de.loewenfelsen.net> 
Gesendet: Dienstag, 13. August 2019 14:09
An: bn at radio42.com
Cc: icecast-dev at xiph.org
Betreff: Re: [Icecast-dev] MetaData Update for FLAC and OPUS

Good afternoon,

On Tue, 2019-08-13 at 13:36 +0200, bn at radio42.com wrote:
> It seems, that with FLAC and OPUS streams (not individual files) the song title (meta data) updates do not work.
> Also the ICEcast admin web interface isn’t working for FLAC and OPUS; while it is working for MP3, AAC as well as OGG streams.
> I.e. when sending a continuous FLAC or OPUS stream to an ICEcast server, it seems impossible to update the meta data mid-stream (like it works for MP3, AAC or OGG).
> I also couldn’t find any way to tell the original FLAC or OPUS encoder to perform the meta data update mid-stream.

Then that is a limitation of the encoder. You should contact the vendor of your encoder and ask them about it.

> Any suggestions?

See my reply here:

> Or are mid-stream meta-data updates simply not supported?

They are. And support is complete beside that they do not show up on the status page for FLAC based streams. But they are passed to the listener correctly.

> If they support, I would be glad about any info on how to implement them.

You must tell your encoder to update the metadata. It's the encoder's job to send them.

> If they are not supported, are there any plans to implement the admin meta data update interface also for FLAC and OPUS?

No. As metadata updates are already supported according to all relevant standards. Anything else would be outside the standards and would likely be more harm than good.

With best regards,

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

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