[FFmpeg-user] New options -preset and -tune for x264 encoding

[sean darcy]

On 04/19/2011 10:05 PM, Baptiste Coudurier wrote:
> On 04/19/2011 03:51 PM, sean darcy wrote:
>> Hi,
>>
>> On 04/19/2011 06:09 PM, Baptiste Coudurier wrote:
>>> Hi Sean,
>>>
>>> On 04/19/2011 03:05 PM, sean darcy wrote:
>>>> On 04/19/2011 03:27 PM, Baptiste Coudurier wrote:
>>>>> Hi,
>>>>>
>>>>> On 04/19/2011 08:56 AM, sean darcy wrote:
>>>>>> On 04/16/2011 08:10 PM, Baptiste Coudurier wrote:
>>>>>>> Hi everyone,
>>>>>>>
>>>>>>> Latest git has now added 2 new options for libx264 encoding:
>>>>>>> -preset<preset>
>>>>>>> -tune<tune>
>>>>>>>
>>>>>>> These options are directly mapped to internal tune and presets within
>>>>>>> libx264. The old presets files have been removed, please use the new
>>>>>>> options.
>>>>>>>
>>>>>>> Best regards.
>>>>>>>
>>>>>> How do these new presets work with 2 passes?
>>>>>>
>>>>>> For instance, I have a script that used:
>>>>>>
>>>>>> -pass 1 -vpre slow_firstpass
>>>>>>
>>>>>> -pass 2 -vpre slow
>>>>>>
>>>>>> I've changed it to:
>>>>>>
>>>>>> -pass 1 -preset slow
>>>>>>
>>>>>> -pass 2 -preset slow
>>>>>>
>>>>>> I used to get 100 fps on the 1st pass, now about 70. Is this to be
>>>>>> expected? Or do I need to do something else on the 1st pass?
>>>>>>
>>>>>> Here's the full script:
>>>>>>
>>>>>> ffmpeg -i $INPUT -an -pass 1  -vcodec libx264 -level 30 -preset
>>>>>> slow     \
>>>>>>           -bufsize 10000000 -maxrate 10000000 -b 1200k -threads 0 -f
>>>>>> mp4 -y
>>>>>> /dev/null
>>>>>> ffmpeg -i $INPUT -an -pass 2  -vcodec libx264 -level 30 -preset slow
>>>>>> -timestamp now \
>>>>>>           -bufsize 10000000 -maxrate 10000000 -b 1200k -threads 0
>>>>>> $1.m4v
>>>>>
>>>>> fastfirstpass should be enabled by default.
>>>>> Can you please double check that the parameters printed are the same ?
>>>>>
>>>>
>>>> I've changed the script a little: slow ->   slower, and added -tune film.
>>>> But on pass 1 there's no fastfirstpass.
>>>
>>> I don't understand what you mean. fastfirstpass is activated by default
>>> like x264, if you want to disable it use: -fastfirstpass 0.
>>>
>>
>>
>> I misunderstood you. I thought you meant check ffmpeg parameters v. x264
>> parameters. I now understand you meant to check if the parameters for
>> ffmpeg were the same with -vpre and -preset. And the answer is yes -
>> they were the same: I was using the identical script.
>
> You have to compare this line:
> [libx264 @ 0x10340b0] 264 - core 115 r1937+22 337ca0a - H.264/MPEG-4 AVC
> codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html -
> options: cabac=1 ref=8 deblock=1:-1:-1 analyse=0x3:0x133 me=umh subme=9
> psy=1 psy_rd=1.00:0.15 mixed_ref=1 me_range=16 chroma_me=1 trellis=2
> 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-3 threads=9
> sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0
> constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=2 b_bias=0 direct=3
> weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40
> intra_refresh=0 rc_lookahead=60 rc=abr mbtree=1 bitrate=1200 ratetol=1.0
> qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=10000 vbv_bufsize=10000
> nal_hrd=none ip_ratio=1.40 aq=1:1.00
>
> between the 2 to make sure they match.
>
>> I'm still puzzled by the new behavior. I'm not sure fastfirstpass is
>> enabled, or maybe something else is slowing the first pass.  With ffmpeg
>> and the old presets, as I remember it, pass 1 was 80-100 fps. pass 2 was
>> 30-40 fps. So pass 1 was about twice as fast as pass 2.
>>
>> With the new settings (bearing in mind I've gone from slow ->  slower)
>> pass 1 is 2 fps _slower_ than pass 2!
>
> Can you please recheck with latest git ?
>
>> frame=91961 fps= 37 q=-1.0 Lsize=       0kB time=3068.37 bitrate=
>> 0.0kbits/s    /s
>>
>> Pass 2:
>>
>> frame=91961 fps= 39 q=-1.0 Lsize=  450992kB time=3068.37
>> bitrate=1204.1kbits/s
>>
>>>> BTW, notice "-level 30" on ffmpeg command line becomes Level 3.1 in
>> x264.
>>>
>>> -level has not effect when -preset is used.
>>>
>>
>> I'm trying to encode so that it can be played on android/iphone. Some
>> models require 3.0 (others are ok with 3.1). I assume some of this will
>> be fixed with -profile, but even within a profile, the levels can be
>> important. But I guess this is an x264 issue, not ffmpeg.
>
> Of course it is important.
> -level should now work, enjoy.
>

Most excellent!

pass 1:

frame=91961 fps=105 q=-1.0 Lsize=       0kB time=3068.37 bitrate= 
0.0kbits/s    s

and it is level 3.0

Thanks enormously for being so responsive.

sean