Icecast Streaming Media Server

[DJ-Zath]

Hi everyone!

Now, I have been doing this for a long long time.. and I have ran into this issue before.. and I'm not sure as to what causes it...

so I'll run it by you all and see what you think...

I have a older (pre-DCMA) hardware-based MP3 encoder, this is a professional piece of equipment that uses the FhG CODEC (not LAME)

since the latest versions of IceCast, however, I have noticed a strange problem..

when I listen to the local AAE feed, its clean and fine, but, when I listen to the return, from Icecast, it sounds like CRAP.. its all splattery and gurgling and sounds like its underwater.. further phase tests on the return stream (from IceCast) show the stream has lost its phase linearity and, in fact, is distorted and unlocked.. the stereo image is all over the place...

if I didn't know better, I'd swear that the stream is being TRANSCODED somewhere, with the LAME encoder, inside IceCast itself.. but I can't tell at this point.. all I know is that any streams passing through it, all come out sounding like "a crappy audicity encode being played on an iPod"

the highs are splattering..
the lows are bottoming out..
the dynamics are GONE...
it sounds like its underwater..
stereo image is very poor...

in short, the audio stream is GREATLY degraded..

now, there is an internal "handoff" from one mount to another to another happening (incoming feed/mount to a "relay" mount on localhost, to the main studio out mount) but this is only if the studio isn't online.. I have verified that this occurs with the studio online or not online (when the studio is online the problem is worse as now the streams pass through icecast twice)

I also should mention that there's a Perl (p5-Shout) script that takes the AAE feed incoming and converts it from UDP to TCP and then assigns it to an IceCast login.. but this script does no transcoding of any kind.

IceCast has ALWAYS been a fine piece of software and I can't imagine this being the culprit.. but, I'm not sure what to do next to either confirm or deny this issue.

any help suggestions would be appreciated!
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-DjZ-

[karlH]

this sort of effect has usually been down to a mismatch of format midstream. samplerate or channel changes are typically of this so I would investigate what exactly is being played and the settings used even if you just take a snapshot and run something like madplay or similar to see the precise detail. icecast itself has never changed the format of the stream.

karl

[DJ-Zath]

Hi Karl!

yeah, it puzzles me as well.. since the AAE interface itself is analog, there's no conversion changes from the AAE through Icecast..

it also seems that rebooting the server helps.. but this is only a temperary measure; the problem will come back

again, thanks for the reply
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-DjZ-

[karlH]

you think the sound card driver is getting messed up? ie the capture settings get confused?

karl.

[DJ-Zath]

sorry for not getting back in awhile...

actually, there's no soundcard/drivers involved as the AAE itself is a piece of streaming hardware, however, there is a conversion process involved and, though that process does not transcode, it does, however, convert UDP into TCP and then assigns it into a Icecast login (single base port with auth)

for now, I suspect the degradation is coming from packet loss in the UDP stream, though I don't know if its from the 'net; incoming, outgoing, or internally when the streams switch mounts on localhost..

for now, the problem has "solved itself" and I haven't noticed any severe issues.. so I have my fingers crossed... I'll keep you posted if I learn anything new.
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-DjZ-