[Icecast] converting mp3's to aac+ or ogg

Chris MacDonald chris at thoughtsoft.net
Sun Jun 25 16:03:48 PDT 2006


Taking the 128 mp3 and re-encoding to flac won't fix any quality issues 
you may have as they will retain the same 'flaws'. In the end you'll end 
up with the same quality as you would have seen going from 128 mp3 to q3 
ogg. One nice thing about ezstream is that you can specify decoders for 
multiple formats so if going and ripping all your media again is too 
daunting a task you could just use the mp3s you have, then slowly start 
ripping to flac as you have time and ezstream will take care of using 
the right decoder.

I'm flattered you think I have customers and all manner of users ;) but 
I just use ezstream/icecast for myself, at least for now I just have my 
one stream. As an example configuration just take a look at the vorbis 
example that comes with ezstream. It's very close to what you want, and 
any changes you need to make are pretty straightforward. Take note 
though, the stream information in the configuration is informational 
only, to actually modify the encoding options of the stream itself.  
Look under the 'reencoding' section of the config and modify the command 
ezstream will use as the encoder. Any options for oggenc you can find 
out by checking out the man pages, but you probably just want to play 
with the with the quality, in which case you'd change '-q 0' to 
whichever you'd like.

To my knowledge it isn't possible to get icecast or ezstream to change 
the bitrate of the stream dynamically to meet a client's bandwidth 
restrictions so what you'd want to do is have two streams, one low 
quality and one high quality. For this you'd be running two instances of 
ezstream, each with their own encoder settings to change the quality to 
suit your needs.

Chris

Dave wrote:
> Hi Chris,
>    Thanks. What i've got are 128kbps mp3's. I encoded them using abcde 
> as it did everything with one command and worked over an entire CD. It 
> used lame as it's backend and encoded at 128k. Question, what if i 
> went from mp3 to flac, which would enable me to have my original mp3's 
> as they are, plus a mirrored area of flac files, then use ezstream to 
> send those flac files as ogg. If that wouldn't blow to much up quality 
> wise i'd rather do it that way than reencode everything. For your 
> streams do you have both dialup and broadband users? If so, i'd like 
> to see your reencode settings so i will know what to punch in, so far 
> getting the quality right has been hit and miss. Are any of your 
> customers windows users using winamp?
> Thanks.
> Dave.
>
> ----- Original Message ----- From: "Chris MacDonald" 
> <chris at thoughtsoft.net>
> To: "Dave" <dmehler26 at woh.rr.com>
> Cc: <icecast at xiph.org>
> Sent: Sunday, June 25, 2006 6:09 PM
> Subject: Re: [Icecast] converting mp3's to aac+ or ogg
>
>
>> Yeah, ezstream is a source client just like ices0, but the manner in 
>> which they go about processing files or playlists may differ. I don't 
>> know too much about ices0 but in the configuration for ezstream you 
>> can either specify a single file to stream or you can point it to an 
>> m3u playlist and it will play though that, I'm not sure this is 
>> compatible with how you currently queue media.
>>
>> In terms of quality, I'm pretty picky which is why I wanted my source 
>> media in a lossless format. I chose flac but there are others, think 
>> wav + compression; tracks I archive are usually 50-80% of their raw 
>> size, of course this varies from track to track. In your case going 
>> from mp3 to ogg, your ability to notice a difference will depend on 
>> the bitrate of the source mp3 and the resultant ogg stream. Something 
>> like a 256kbps vbr mp3 to a q3 (~110kbps vbr) ogg vorbis stream will 
>> still sound fine (I did this before deciding to do al my archiving in 
>> flac), but if you took a 128kbps mp3 and did the same you'd notice 
>> the change. Again, it varies from person to person and I'd imagine 
>> you'd just have to try it yourself to see what you'd like, it's less 
>> a science and more a preference.
>>
>> The box that does my re-encoding on is an AMD 1800 with 512MB RAM and 
>> also does icecast, apache, mysql, sendmail, pretty much the whole 
>> shebang and I haven't had a problem. Though, mind you I'm only 
>> re-encoding for one stream whereas you'd be doing multiple streams. 
>> The flac decoder seems content with ~2% of the processor and the ogg 
>> encoder seems to like ~40% and again, this is hardly a science and 
>> undoubtedly 'your mileage will vary'.
>>
>> Chris
>>
>> Dave wrote:
>>> Hi Chris,
>>>    Yes that helps a lot, thanks. I'm currently using ices0, which 
>>> worked fine when all i wanted to stream was mp3's. You've sold me on 
>>> ogg, and ezstream can it work as ices0 does? As i said i'd really 
>>> not like to do all this reencoding again, how much of a quality loss 
>>> will i be looking at if i go from mp3 to ogg? I'm not familiar with 
>>> the flac format at all. Does it have any kind of compression, i'd 
>>> rather not have something like all these wavs around or similar if i 
>>> could help it. As for the box how much of a hit will it take? What 
>>> kind of machine do you use for your encoding?
>>>    Thanks.
>>> Dave.
>>>
>>> ----- Original Message ----- From: "Chris MacDonald" 
>>> <chris at thoughtsoft.net>
>>> To: "Dave" <dmehler26 at woh.rr.com>
>>> Cc: <icecast at xiph.org>
>>> Sent: Sunday, June 25, 2006 4:46 PM
>>> Subject: Re: [Icecast] converting mp3's to aac+ or ogg
>>>
>>>
>>>> Hey Dave,
>>>>
>>>> Personally I use ezstream as a source client as it's designed to 
>>>> re-encode your stream (it's available at www.icecast.org). I've set 
>>>> up my radio to re-encode my archived flacs to ogg vorbis then out 
>>>> to icecast and it works quite well.
>>>>
>>>> As for quality, vorbis is apparently one of the nicer formats at 
>>>> low bitrates. I'm not sure about aac though, I'd imagine there 
>>>> isn't much in the way of support for it so you'd be much better off 
>>>> with ogg. Either way though, re-encoding from a lossy format (mp3) 
>>>> to another lossy format (ogg/aac) you'll notice some sound 
>>>> degradation from your source mp3, this is entirely why I archive in 
>>>> flac.
>>>>
>>>> I'm not sure what you want to do for dialup/broadband quality 
>>>> settings but I'd probably just run two mounts for each station, one 
>>>> low bitrate and one higher. One thing you have to keep in mind 
>>>> though is that all this re-encoding would happen on the fly so you 
>>>> need to make sure the machine you'd be doing it with was up to the 
>>>> task.
>>>>
>>>> Not sure if any of the above helps, but I'd imagine it presents 
>>>> some options at least.
>>>>
>>>> Chris
>>>>
>>>> Dave wrote:
>>>>> Hello,
>>>>>    I've got a FreeBSD 6 machine running icecast2 and 
>>>>> ices0streaming four different streams of mp3's. Now i have a need 
>>>>> to stream the same content as either aac+ or ogg vorbis whichever 
>>>>> would be easiest to set up and give the best quality. I want these 
>>>>> new streams to handle both broadband and dialup users without 
>>>>> sacrificing quality. My problem is i really really do not want to 
>>>>> have to manually go through my media again and bring them in to 
>>>>> aac+ or ogg, doing it once for mp3 was bad enough. I used abcde to 
>>>>> handle this, and as i said i'd like to find an automated way of 
>>>>> reworking these files. Any suggestions welcome.
>>>>> Thanks.
>>>>> Dave.
>>>>>
>>>>> _______________________________________________
>>>>> Icecast mailing list
>>>>> Icecast at xiph.org
>>>>> http://lists.xiph.org/mailman/listinfo/icecast 



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