[FFmpeg-devel] [PATCH 2/2] MxPEG decoder

[Anatoly Nenashev]

On 13.11.2010 04:24, Michael Niedermayer wrote:
> On Thu, Nov 11, 2010 at 02:16:27AM +0300, Anatoly Nenashev wrote:
>    
>> On 10.11.2010 18:28, Michael Niedermayer wrote:
>>      
>>> On Wed, Nov 10, 2010 at 06:08:47PM +0300, Anatoly Nenashev wrote:
>>>
>>>        
>>>> [...]
>>>> If to read more than 16 byte at once then it is required additional
>>>> operations of memcpy and memmove.
>>>> For example. If I read buffer of 256 bytes in which audio packet
>>>> available in position 10 and size 100 then I need
>>>> to copy data of size 100-10=90 in new audio packet and move data of size
>>>> 256-100=156 in internal buffer. I think this may reduce the performance.
>>>>
>>>>          
>>> you dont need to move it.
>>>
>>> and the overhead of all your code executed once every 16 bytes will reduce
>>> performance more than an occasional memcpy(). That said it can be done
>>> without memcpy by accessing the internal buffer but iam not suggesting this
>>> to be done.
>>>
>>>        
> There are many ways to implement this, one simple one is
> you have a internal buffer
> you read into it
> you return AVPackets that point into this buffer and have destruct=NULL
>
>    

Implemented this way.

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