[FFmpeg-devel] atrac1 decoder and aea demuxer rev 6

[Maxim]

Michael Niedermayer schrieb:
> On Sun, Sep 06, 2009 at 08:12:04PM +0200, Benjamin Larsson wrote:
>   
>> Changes:
>>     
> [...]
>   
>> Changed some code.
>>     
>
> :)
>
>
>   
>> Did not do anything to the qmf routines that will be shared with atrac3
>> as it will be a svn copy and I'll take comments on that when the code is
>>  split out in it's own file.
>>
>> Thanks for all the comments so far.
>>     
> [...]
>
>   
>> +
>> +static const uint8_t bfu_bands_t[4]  = {0, 20, 36, 52}; // number of BFUs in each QMF band
>> +
>> +/* number of spectral lines in each BFU */
>> +static const uint8_t specs_per_bfu[52] = {
>> +     8,  8,  8,  8,  4,  4,  4,  4,  8,  8,  8,  8,  6,  6,  6,  6, 6, 6, 6, 6, // low band
>> +     6,  6,  6,  6,  7,  7,  7,  7,  9,  9,  9,  9, 10, 10, 10, 10,             // midle band
>> +    12, 12, 12, 12, 12, 12, 12, 12, 20, 20, 20, 20, 20, 20, 20, 20              // high band
>> +};
>>     
>
> i guess i knew it once but what is a bfu? ill probably figure it out in a
> few seconds when looking at the use of these but i think it could help if
> its written out here somewhere
>   

bfu = block floating unit = group of spectral frequencies having the
same quantization parameters like word length and scale factor...

Regards
Maxim