[FFmpeg-soc] [PATCH] AMR-WB Decoder

[Marcelo Galvão Póvoa]

On 4 September 2010 06:02, Vitor Sessak <vitor1001 at gmail.com> wrote:
> On 09/03/2010 11:50 PM, Marcelo Galvão Póvoa wrote:
>>
>> Also, whether with this patch or not I guess my output to the first
>> sample above (attached) is not good compared to the reference decoder.
>> The are some sharp peaks that can be seen with Audacity, one of them
>> also with clipping. The stddev I've got seems ugly:
>> stddev:  884.86 PSNR: 37.39 MAXDIFF:23298 bytes:   473600/   473600
>>
>
> Indeed, the stddev is not particularly good, but don't trust only it to do
> comparisons. A very small phase shift can completely ruin the stddev.
>
> Do you see sharp peaks in your output that are not there in the reference
> decoder? Or the sharp peaks shows up when you invert and superpose the
> waves? Do these sharp peaks gives audible artifacts?
>

Sorry, I've forgot to mention that I was comparing the reference
decoder output waveform with mine. In general, they look mostly the
same but there are some 3 or 4 points in which my decoder gives a
short peak. I couldn't notice audible artifacts at these moments.

>> Inverting one of the waves and playing them simultaneously I can hear
>> some intermittent artifacts, so I guess there is still something wrong
>> with the decoder.
>>
>
> This is also something that is very sensible to a tiny phase difference...
>

It's good to know.

-- 
Marcelo