[FFmpeg-devel] [PATCH] Fix non-rounding up to next 16-bit aligned bug in IFF decoder

[Sebastian Vater]

M?ns Rullg?rd a ?crit :
> Michael Niedermayer <michaelni at gmx.at> writes:
>
>   
>> On Thu, Apr 29, 2010 at 03:36:07PM +0200, Sebastian Vater wrote:
>> [...]
>>     
>>> static void decodeplane8(uint8_t *dst,
>>>                          const uint8_t *buf,
>>>                          const unsigned buf_size,
>>>                          const unsigned bps,
>>>                          const unsigned plane)
>>> {
>>>     START_TIMER;
>>>     const uint8_t *end = dst + (buf_size * 8);
>>>     const uint64_t *lut = plane8_lut[plane];
>>>     for(; dst < end; dst += 8) {
>>>         const uint64_t v  = AV_RN64A(dst) | lut[*buf++];
>>>         AV_WN64A(dst, v);
>>>     }
>>>     STOP_TIMER("decodeplane8");
>>> }
>>>       
>> this looks very nice
>>     
>
> Is the length always a multiple of 8 now?  Earlier you said 4...
> What's the deal?
>   

Seems you're mixing this with sth. up...

length is now word aligned, i.e. 16 bits (thus a multiple of buf_size * 16).
dst is AVPacket->data aligned. Don't know exactly what ffmpeg uses to
align this.
buf is always 16 bits aligned.

Each line in dst is frame.linesize[0] aligned...here I also don't know
the alignment.

But I assume that AVPacket->data and AVFrame->linesize[0] are aligned to
16 bytes for allowing e.g. MMX processing the image data. ;-)

-- 

Best regards,
                   :-) Basty/CDGS (-: