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

[Anatoly Nenashev]

On 15.11.2010 03:27, Anatoly Nenashev wrote:
> 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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