[FFmpeg-user] libx264 options through FFmpeg

[Tim Nicholson]

On 30/06/11 15:30, Thomas Worth wrote:
> On Thu, Jun 30, 2011 at 3:22 AM, Tim Nicholson<tim.nicholson at bbc.co.uk>  wrote:
>> On 30/06/11 11:08, Tim Nicholson wrote:
>>>
>>> On 28/06/11 17:51, Thomas Worth wrote:
>>>>
>>>> On Tue, Jun 28, 2011 at 8:31 AM, Tim
>>>> Nicholson<tim.nicholson at bbc.co.uk>  wrote:
>>>>>
>>>>> On 22/06/11 06:43, Thomas Worth wrote:
>>>>>>
>>>>>> While I've historically used a standalone x264 binary to do encoding
>>>>>> by piping yuv420p from FFmpeg, I thought I'd try libx264 through
>>>>>> FFmpeg since it's certainly more convenient.
>>>>>>
>>>>>> [....]
>>>>>>
>>>>>> If I can safely pass all my options via -x264opts then I'll just use
>>>>>> that from now on and disregard FFmpeg's x264 interface.
>>>>>
>>>>> But what about options that require colon delimited parameters
>>>>> themselves
>>>>> such as "--sar 1:1"?
>>>>
>>>> If I use a forward slash (sar=16/9), libx264 doesn't complain but it
>>>> also doesn't use the supplied ratio. It seems to default to "1/1"
>>>> every time.
>>>
>>> I have tried sar="1:1" and it hasn't complained about that.
>>>
>>> Howver it doesn't want to accept a profile specification. Using:-
>>>
>>> ffmpeg -i $in_file -vcodec libx264 -pix_fmt yuv420p -s 1920x1080 -an \
>>> -x264opts bitrate=35000:preset=veryslow:tune=$tune:\
>>> [...]
>>>
>>> I get a:-
>>> "[libx264 @ 0x12e0960] bad value for 'preset': 'veryslow'"
>>>
>>> error. replace "veryslow" with whatever you like from the legal list.
>>>
>>
>> Actually its worse than that, it also doesn't accept any of the --tune
>> parameters, or seem to handle options that don't have values, e.g --tff
>
> Yes, I had the same problems. What I found is that libx264 seems to
> take all parameters through x264opts except the following:
>
> preset
> profile
> tune
>
> For some reason, it says "bad value for preset..." etc. But, and check
> this out, if you supply any random value, you get the same error: "bad
> value for 'giggity': 'goo'". So, it doesn't look like it even
> recognizes it.
>
> I do this:
>
> ffmpeg -i file.mov -an -vcodec libx264 -preset medium -profile
> baseline -tune film -x264opts $OPTS out.mp4
>
> That seems to be working.
>

Well so it does.... Thanks

> I just saw your email about parameters that don't take values, and
> you're correct. tff=1 or aud=1 or 8x8dct=0 is the way you turn them on
> or off.
>

Or not quite as it happens.

if you set :fake-interlaced=1: the x264 header showing the set 
parameters reports "interlaced=fake".

However if you set tff=1 or bff=1 you get "interlaced=0" suggesting that 
these are not working.

btw I see there is now a "bluray-compat" switch that saves having to 
explicitly specify a number of others, such as nal_hrd and b_pyramid.


-- 
Tim

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