[FFmpeg-user] Multi-core transcoding (performance tuning)

[Andy Sheen]

Brian Cardarella wrote on Thu 21 Jul at 18:34 UK time
> Sure,
>
> ffmpeg -i 58518579.mp4 -ss 00:00:16.5 -qscale 5 -strict experimental
> -threads 10 -y out.mp4
>

You actually need to tell it to recode. Add a -vcodec libx264 and 
(presumably -acodec copy). I'm not up on the latest presets, but it's 
probably maxing out the read/write rate of your disk.


> - Brian
>

Andy

> On Thu, Jul 21, 2011 at 1:31 PM, Jonathan Isom<jeisom at gmail.com>  wrote:
>> On Thu, Jul 21, 2011 at 12:24 PM, Brian Cardarella
>> <bcardarella at gmail.com>  wrote:
>>> So, -threads will distribute the load some but now the transcoding is
>>> topped out at 85fps. I am distributing across all 7 cores and the CPU
>>> usage has only gone up 30 - 50%. It seems there is some other
>>> bottleneck that is happening here. Any thoughts?
>>
>> It would be useful for what you command line is.
>>
>>> - Brian
>>>
>>> On Thu, Jul 21, 2011 at 1:21 PM, Brian Cardarella<bcardarella at gmail.com>  wrote:
>>>> NM, I found the -threads option.
>>>>
>>>> - Brian
>>>>
>>>> On Thu, Jul 21, 2011 at 1:19 PM, Brian Cardarella<bcardarella at gmail.com>  wrote:
>>>>> Does FFMPEG support any way to distribute the transcoding across
>>>>> multiple cores? I notice that on my Intel Core i7 one of the cores is
>>>>> maxed at 100% and the rest are idle. In addition, the process itself
>>>>> seems to only be 20MBs. Would FFMPEG benefit from putting the entire
>>>>> video in memory?
>>>>>
>>>>> I'm very interested in any performance tuning suggestions. I don't
>>>>> want to reduce the quality of the video but currently it is
>>>>> transcoding at about 75fps. I feel like there is room to grow here.
>>>>>
>>>>> - Brian
>>>>>
>>>>
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