Fix de/selection of libx264 I-partitions

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Hi,

I've noticed that when using ffmpeg, using -partitions
-parti4x4 doesn't
work as I had expected. Although I was trying to disable the
generations
of 4x4 blocks, the output of ffmpeg would still contain:
...
mb I  I16..4: 59.1%  0.0% 40.9%
...

The attached patch fixes the selection and deselection of
the usage of
certain blocksizes when using libx264.

libx264.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)


With friendly regards,
Takis
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On Thu, 26 Jul 2007, Panagiotis Issaris wrote:

> I've noticed that when using ffmpeg, using -partitions
-parti4x4 doesn't
> work as I had expected. Although I was trying to
disable the generations
> of 4x4 blocks, the output of ffmpeg would still
contain:
> ...
> mb I  I16..4: 59.1%  0.0% 40.9%
> ...
>
> The attached patch fixes the selection and deselection
of the usage of
> certain blocksizes when using libx264.

ffmpeg is currently consistent with mencoder and x264cli:
the "partitions" 
option affects only P- and B-frames, while I-frames always
use all 
available partitions. Because the only reason for disabling
partitions is 
speed, and intra partitions in I-frames gain much more
compression per 
cpu-time than in P- and B-frames.

If you want some way to disable partitions in I-frames,
that's another 
question. But don't change the meaning of an existing
option.

--Loren Merritt
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Hi,

Loren Merritt wrote:
> On Thu, 26 Jul 2007, Panagiotis Issaris wrote:
>
>   
>> I've noticed that when using ffmpeg, using
-partitions -parti4x4 doesn't
>> work as I had expected. Although I was trying to
disable the generations
>> of 4x4 blocks, the output of ffmpeg would still
contain:
>> ...
>> mb I  I16..4: 59.1%  0.0% 40.9%
>> ...
>>
>> The attached patch fixes the selection and
deselection of the usage of
>> certain blocksizes when using libx264.
>>     
>
> ffmpeg is currently consistent with mencoder and
x264cli: the "partitions" 
> option affects only P- and B-frames, while I-frames
always use all 
> available partitions. Because the only reason for
disabling partitions is 
> speed, and intra partitions in I-frames gain much more
compression per 
> cpu-time than in P- and B-frames.
>
> If you want some way to disable partitions in I-frames,
that's another 
> question. But don't change the meaning of an existing
option.
>
>   
Ah, I see. Well, from a user point of view, it seemed
logical to me that
disabling I4x4 blocks would do so in both I and P frames,
but I also
think my patch was wrong in that sense too. It should have
also kept
OR-ing analyse.inter with the I4x4's and I8x8's as I now
always entirely
disabled them for P frames, right?

I'll try to prepare a different patch, introducing a way to
disable them
for I frames, without changing existing options.

With friendly regards,
Takis
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