[Icecast] Transcode lossy to further reduced lossy to stream over Icecast

[D.T.]

I created some test samples and transcoded to FDK AAC and libopus at
fairly low bitrates - I cannot recreate what bothered me about Opus &
noisy music previously.
It also seems I cannot tease ffmpeg into encoding FDK's AAC with VBR.
As it stands, Opus clearly wins in this scenario.*

Q:
Is it possible to stream in variable bitrate?


*
ffmpeg -i "$track" -vn -ac 2 -c:a libfdk_aac -profile:a aac_he_v2 -b:a $br -vbr 5 "${track}.HEv2_$br.aac"
ffmpeg -i "$track" -vn -ac 2 -c:a libopus -b:a $br -vbr on "${track}.vbr$br.ogg"


On Sat, 2023-04-15 at 16:17 -0500, Brad Isbell wrote:
> Opus or AAC will give you comparable results at reasonable bitrates
> (~128k).
> Though, I would suggest finding a way to get more storage.  You could
> upload to Backblaze B2 or AWS S3 for pennies, if your current host
> won't let you upgrade.
> 
> On Sat, Apr 15, 2023 at 3:36 PM D.T. <ohnonot-github at posteo.de>
> wrote:
> > Situation: 
> > * remote virtual server with very little storage (estimate: I can
> > spare about 40G for music)
> > * local music collection of ~80G in all sorts of formats - lossy in
> > varying quality, some lossless too
> > 
> > Vision:
> > * stream my whole music collection randomized so I can listen to it
> > anywhere
> > 
> > Plan/Idea:
> > * Locally transcode everything to one format that results in files
> > that are 
> > - small enough to fit on my server, altogether
> > - have a reduced bitrate for streaming
> > - can be streamed as-is without further transcoding
> > * Upload
> > * Set icecast up to do just that (this I know how to do)
> > 
> > So I'm asking advice for the transcoding. What's likely to give the
> > best results with already lossy sources, and at small bitrates?
> > 
> > According to these documents:
> > https://trac.ffmpeg.org/wiki/Encode/HighQualityAudio
> > https://wiki.hydrogenaud.io/index.php?title=Transcoding#Lossy-to-lossy_transcoding
> > it basically comes down to Fraunhofer Institute's FDK AAC, but the
> > articles are dated.
> > Opus is supposed to be good but I always have the impression it
> > doesn't deal well with loud/grungy/fuzzy/guitarry music, esp. at
> > low bitrates.
> > 
> > What do you say?
> > 
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