[theora] Theora encoder performance

[Mircea Gliga]

Gregory Maxwell wrote:
> On Mon, Dec 7, 2009 at 9:56 AM, Benjamin M. Schwartz
> <bmschwar at fas.harvard.edu> wrote:
>   
>> Mircea Gliga wrote:
>>     
>>>    Then I measured how long does it take for Theora to encode an image
>>>       
>> ...
>>     
>>>    On average: *80 ms*.
>>>      Using XVID I've obtained between *20-25 ms* for an image. That's
>>> 60ms longer using Theora.
>>>       
>> That is surprising.  A big difference like this is definitely not
>> expected.  Are you encoding at approximately the same bitrate?  Video
>> encoding speed depends heavily the target bitrate or quality.  What
>> version of libtheora are you linking against?  Apart from switching out
>> XVID and Theora, is the code otherwise identical?
>>     
>
> "OS Name    Microsoft® Windows Vista™ "
>
> How is libtheora compiled? Are assembly optimizations enabled? Is this an
> x64 build?
>
>   

I'm using the latest version from theora's site, ver 1.1.1
I've compiled libtheora using the projects provided in the downloaded 
package
with no modifications to the Project's properties. I've tried both of this
configurations: Release, Release_SSE2. The target platform is *Win32*, 
it's not a x64 build.

/ Apart from switching out
XVID and Theora, is the code otherwise identical?/

Yes the code is identical. I measured how long does it take for the API 
calls to execute: /th_encode_ycbcr_in/ and /
th_encode_packetout/ calls, for theora, and xvid_encore for xvid.

When initializing the encoder, I set the bitrate: 
/theoraInfo.target_bitrate = 0/; and /theoraInfo.quality/ = 30.
 From the documentation: /int th_info::target_bitrate > If initializing 
an encoder with this struct, set this field to a non-zero value to 
activate CBR encoding by default./

 From /libtheora Property Pages>Optimization/ in VS 2008:
    Optimization Maximize: Speed (/O2)
    Inline functions expansion: Any Suitable (/Ob2)
    Enable intrinsic functions: Yes (/Oi)
    Favor size or speed: Favor Fast Code (/Ot)
    Favor Fast Code (/Ot): Favor Fast Code (/Ot)

Mircea Gliga


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