[Libav-user] FFmpeg parallel H264 Decoding

Christian Brümmer christian.bruemmer at gmx.de
Sun Aug 5 19:43:43 CEST 2012

Am 05.08.2012 19:03, schrieb Carl Eugen Hoyos:
> Christian Brümmer <christian.bruemmer at ...> writes:
>> I was wrong. i am using one of the head/snapshot
>> (git://source.ffmpeg.org/ffmpeg.git) version from june 2012!
> That's still old.
>> okay - so what about parallel decoding?
> Just pass a number greater than your core count to thread_count.
> Please do not top-post here, Carl Eugen
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Oh, 2 month ago is too old? I was not aware of such a progress.

In the docs AVCodecContext::thread_count is marked as "encoding: Set by 
user" (nothing about decoding). So i thought it will not affect the 
decoding performance.
Ah but i see in AVCodecContext::execute there is a hint "decoding: Set 
by libavcodec, user can override. "

Okay, i will give it a try! Thank you for your fast reply!

I've another question cause it seems that you are familiar with FFmpeg 
and its dependancies. The problem beside decoding (@Android Phone )is 
the Color-Conversion from YUV to RGBA. I m using swscale (performance is 
worse ~ about the decoding time) and i heared about splitting the image 
in two parts and use swscale parallel for each part. Is that possible? 
If not - is there a way to speed up colour conversion (some thing like 
"thread_count") for android? I get a log output that says there is no 
hardware acceleration for colour conversion - is that still right or is 
there a patch somewhere to use advanced neon commands for color-conversions?

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