[FFmpeg-devel] [PATCH] V210 decoder and encoder

[Baptiste Coudurier]

Hi Ramiro,

On 5/11/2009 4:23 PM, Ramiro Polla wrote:
> On Mon, May 11, 2009 at 6:41 PM, Baptiste Coudurier
> <baptiste.coudurier at gmail.com> wrote:
>> On 5/11/2009 1:59 PM, Reimar D?ffinger wrote:
>>> On Mon, May 11, 2009 at 12:35:49PM -0700, Baptiste Coudurier wrote:
>>>> On 5/11/2009 12:27 PM, Reimar D?ffinger wrote:
>>>>>> +            *udst++ = (v & 0x3FF)      <<  6;
>>>>>> +            *ydst++ = (v & 0xFFC00)    >>  4;
>>>>>> +            *vdst++ = (v & 0x3FF00000) >> 14;
>>>>> Both
>>>>>
>>>>>> +            *udst++ = (v & 0x000003FF) <<  6;
>>>>>> +            *ydst++ = (v & 0x000FFC00) >>  4;
>>>>>> +            *vdst++ = (v & 0x3FF00000) >> 14;
>>>>> and
>>>>>
>>>>>> +            *udst++ = (v <<  6) & 0xFFC0;
>>>>>> +            *ydst++ = (v >>  4) & 0xFFC0;
>>>>>> +            *vdst++ = (v >> 14) & 0xFFC0;
>>>>> Seem nicer to me.
>>>> I don't get what you mean.
>>> That I consider both alternatives more readable.
>>>
>>>>> I think the later one might have a speed advantage due to needing only one
>>>>> constant.
>>>>> Also like in the encoder you don't really need one of the ands.
>>>> You mean ydst >> 14 ? What if the 2 bits are not zero ? Doesn't the bit
>>>> gets replicated ?
>>> No, the << 6 one, Upper bits are dropped because udst is only 16 bits, lower
>>> bits 0 is shifted in. Thus the & is pointless.
>> I see what you mean now.
>>
>> Update attached.
> 
>> +            v= le2me_32(*src++);
>> +            *udst++ =  v <<  6;
>> +            *ydst++ = (v >>  4) & 0xFFC0;
>> +            *vdst++ = (v >> 14) & 0xFFC0;
>> +
>> +            v= le2me_32(*src++);
>> +            *ydst++ =  v <<  6;
>> +            *udst++ = (v >>  4) & 0xFFC0;
>> +            *ydst++ = (v >> 14) & 0xFFC0;
>> +
>> +            v= le2me_32(*src++);
>> +            *vdst++ =  v <<  6;
>> +            *ydst++ = (v >>  4) & 0xFFC0;
>> +            *udst++ = (v >> 14) & 0xFFC0;
>> +
>> +            v= le2me_32(*src++);
>> +            *ydst++ =  v <<  6;
>> +            *vdst++ = (v >>  4) & 0xFFC0;
>> +            *ydst++ = (v >> 14) & 0xFFC0;
> 
> Maybe:
> #define FOOBAR(a, b, c) \
> [...]
> 
> FOOBAR(u, v, y)
> FOOBAR(y, u, y)
> FOOBAR(v, y, u)
> FOOBAR(y, v, y)
> 
> And there are some more further down the patch.

Why not, updated patch attached.

-- 
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
FFmpeg maintainer                                  http://www.ffmpeg.org
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