[MEncoder-users] x264 encoding slower after updating libx264

belcampo belcampo at zonnet.nl
Mon Nov 16 17:39:25 CET 2009


Grozdan wrote:
> On Mon, Nov 16, 2009 at 4:13 PM, belcampo <belcampo at zonnet.nl> wrote:
>> belcampo wrote:
>>> Loren Merritt wrote:
>>>> On Sat, 14 Nov 2009, Dâniel Fraga wrote:
>>>>> On Sat, 14 Nov 2009, Loren Merritt wrote:
>>>>>
>>>>>> MB-tree is enabled by default now, didn't exist in api67, and takes a
>>>>>> bunch of memory.
>>>>>> B-frames and multiref are enabled by default now, weren't in api67, and
>>>>>> take some memory and cpu-time.
>>>>>> RDO, trellis, and several other options are enabled by default
>>>>>> now, weren't in api67, and take cpu-time.
>>>>>> All of the above also affect filesize.
>>>>>    And all of these options result in better quality? Because I
>>>>> didn't notice any improvement in the quality... of course I'm just
>>>>> looking at the video (I didn't do any scientific comparison).
>>>> All of these options result in better compression ratio. That can be
>>>> either better quality or lower bitrate, depending on what ratecontrol mode
>>>> you choose.
>>> So if I understand correct, given a constant quality, it would result in a
>>> smaller file ?
>>>> --Loren Merritt
>>>>
>>>>
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>>>>
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>> I did some testing with current ffmpeg/x264 in comparison with ffmpeg
>> SVN-r17923/x264-65
>> convert 400frames from BBC-HD source to 720x576
>>
>> Current version
>> [libx264 @ 0x8a537d0]frame I:5     Avg QP:22.00  size: 38218
>> [libx264 @ 0x8a537d0]frame P:395   Avg QP:22.00  size:  6277
>> size 2670643
>> time 0:30.10
>> Memory use 155m  95m ffmpeg
>>
>> SVN-r17923/x264-65
>> [libx264 @ 0x89fc430]slice I:5     Avg QP:22.00  size: 38065
>> [libx264 @ 0x89fc430]slice P:395   Avg QP:22.00  size:  6565
>> size 2784070
>> time 0:25.31
>> Memory use 94428  42m ffmpeg
>>
>> Indeed size is better by 4.08%
>> But time is worse by almost 19%
>> Memory needed more than doubles
> 
> That's because of mbtree... it needs pretty much a lot of memory, even
> more so when you increase rc_lookahead
I was looking for an ffmpeg option to disable mbtree with -mbtree 0 but 
that wasn't a recognized option, also tried -mb-tree 0, but to no avail
> 
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