[FFmpeg-devel] Concurrent ProRes decoder

Deron Kazmaier deron at pagestream.org
Wed Sep 21 16:33:47 CEST 2011

On 9/21/11 1:41 AM, Reimar Döffinger wrote:
> On 21 Sep 2011, at 03:42, Maxim<max_pole at gmx.de>  wrote:
>> My code may be of particular interest because of:
>> - compatible license (LGPL)
>> - a full description of the codec (especially its headers and encoding
>> algorithms) I'm going to make publicitly available soon
>> - maintainership by a real person instead of an anonymous one
>> Therefore I let you, crews, to make a final decision about all that...
> Good arguments, though the lack of slice multithreaded decoding is significant, the decoder in FFmpeg already has at least one (MPlayer) user relying on the speedup from that...

That would be me. I'm running 8 slices (the max it will let me) and it 
is barely cranking out 720p 59.94fps on a dual Xeon 2.6Ghz board 
(actually, the CPUs might be a little faster than that now that I think 
about it). Please don't take the multithreading away! I am doing this 
for a friend (well, and free rack space and coolness) who can generate 
all sorts of ProRes files from some nice raw footage and more 
importantly has an eye for signal quality that I don't. He was very 
pleased with last night's test where I actually took over a feed into a 
Miami transmitter and broadcast prores files over the air directly from 
the computer. A couple times the system would drop/late frame but over 
all worked great.

I did find at least one professionally generated (with FCP on a Mac) 
segment that spewed out errors about incorrectly encoded bits. It did 
still seem to play ok. Too much was going on and I didn't save the name 
of the file but I know roughly where it is and I can find it again. The 
only problem will be that most of the files we are testing with start at 
400mb for a statio ID (like a 3 second segment) and the file in question 
was something like 16gb. Not sure if I have something that will cut it 
up without changing the raw data.

That all said, what can I do to help? I'm pumped after last night. I 
have not had this much fun with a computer in a long time.

Thanks so much to everyone that took part in making this happen!!! I was 
compiling and hating 32bit mplayer to use the apple prores codec just a 
week ago and look at it now.

(Sorry for butting in. Now what is it going to take for a faster decoder 
and an encoder :-)


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