Re: iPhone SW Decoding Performance of MP3 vs AAC
Re: iPhone SW Decoding Performance of MP3 vs AAC
- Subject: Re: iPhone SW Decoding Performance of MP3 vs AAC
- From: William Stewart <email@hidden>
- Date: Thu, 8 Apr 2010 13:14:09 -0700
Unless you really really need to be concerned about this, I would use the format that best suits your needs - by and large, AAC decoding will be more efficient in our implementations than MP3
Bill
On Apr 8, 2010, at 11:56 AM, Stephen Davis wrote:
> Your test isn't really meaningful in the context of your opening statement.
>
> The statement that AAC decoding "should" be more efficient than MP3 is only relevant if the two SW decoders have received the same level of optimization tweaks. In other words, a plain vanilla AAC decoder will obviously be more expensive than a highly optimized MP3 decoder even though the latter's compression algorithm might indicate that it *should* be more expensive.
>
> I have no knowledge of the implementation details on the iPhone but it's certainly possible that most of the optimization work has been done on the hw-accelerated path for AAC decoding since that is the common case. In other words, it is perfectly reasonable for the SW AAC decoder to be less efficient than the SW MP3 decoder on iPhoneOS.
>
> What you have compared is two specific SW implementations, not the complexity of the compression algorithms.
>
> hth,
> stephen
>
> On Apr 8, 2010, at 11:43 AM, McD wrote:
>
>> Sorry. I meant decoding. Everything I wrote relates to decoding. No encoding was done. Any ideas?
>>
>> --- On Thu, 4/8/10, James McCartney <email@hidden> wrote:
>>
>> From: James McCartney <email@hidden>
>> Subject: Re: iPhone SW Decoding Performance of MP3 vs AAC
>> To: "McD" <email@hidden>
>> Cc: email@hidden
>> Date: Thursday, April 8, 2010, 1:15 PM
>>
>>
>>> My understanding is that AAC should be more efficient than MP3 for SW decoding.
>>> ...
>>> However, my results seem to indicate the opposite.
>>> ...
>>> I am getting 0.79-0.92 CPU time for AAC encoding and 0.65-0.68 for the mp3 encoding. This result indicates the opposite of what I've read is correct.
>>
>> ?
>> first you talk about decoding performance then you compare encoding performance.
>
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