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

[Marcelo Galvão Póvoa]

On 4 September 2010 15:16, Vitor Sessak <vitor1001 at gmail.com> wrote:
> On 09/04/2010 05:22 PM, Marcelo Galvão Póvoa wrote:
>>
>> 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.
>>
>
> It does looks like a bug :(
>

I've just tested dumping all the voice_factor() values from the
reference decoder (I suspected this function was problematic) and the
output difference was not too much:

all_man.awb stddev:    0.38 PSNR:104.69 MAXDIFF:    4 bytes:   473600/   473600

The sharp peaks and the clipping are still there, so I guess we can
discard checking this function.

-- 
Marcelo