Re: High performance MP3 decoder (was Re: SoundComponentData to AudioStreamBasicDescription)
Re: High performance MP3 decoder (was Re: SoundComponentData to AudioStreamBasicDescription)
- Subject: Re: High performance MP3 decoder (was Re: SoundComponentData to AudioStreamBasicDescription)
- From: Bill Stewart <email@hidden>
- Date: Thu, 24 Jan 2002 16:43:14 -0800
on 20/1/02 4:14 AM, Lieven Dekeyser wrote:
>
>>> Why not use the AudioConverter - at least if you're just doing OS X that is
>
>>> a better alternative..
>
>>
>
>> I know, but my app needs to be able to handle compressed variable bitrate
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>> formats like mp3s, so I figured it would be best to use the SoundConverter
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>> API. It enables me to handle all audio formats QuickTime can handle with
>
>> the same code... That's not possible with the AudioConverter, right? (only
>
>> fixed rate LinearPCM, right?) Or did I look over something?
>
>
>
> At this stage yes. In the longer term we will address this shortcoming. You
>
> might want to use the AC where you can and then fall back to the SC when you
>
> need to. The AC will also allow for multi-channel data, which the SC won't
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> do.
>
>
Any idea on when this will be done? I'm writing an application that
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needs realtime high performance MP3 decoding. The SoundConverter works,
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but it uses up to 90% cpu time on my iBook 500, which isn't acceptible at
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all. When playing 2 songs at the time, even simply dragging a window
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causes the sound to skip. it doesn't skip when inserting/ejecting a cd
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though... eat this iTunes :)
>
Anyway.. I'd like to finish the first version of my app in the next 2
>
months. Any chance the AudioConverter will be able to handle MP3s by then?
No... Not in 2 months. If I playback an MP3 file with QT I only see about a
5-6% usage on a tibook. This is using the same decoder code exactly as the
SoundConverter, so I'm very confused about why you're seeing a 90% load...
Bill
mailto:email@hidden
tel: +1 408 974 4056
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