[Ffmpeg-devel] [PATCH] AVOption defaults sync

[Baptiste Coudurier]

Panagiotis Issaris wrote:
> Hi,
> 
> Op donderdag 14 september 2006 15:01, schreef Baptiste Coudurier:
>> [...]
>>>>> The attached patch synchronizes the defaults specified in the AVOptions[] array 
>>>>> to the defaults specified in the ffmpeg.c global static variabels. I took the
>>>>> ones specified in ffmpeg.c as the new ones for AVOptions, as this preserves the 
>>>>> current behavior. Regression tests pass.
>>>> looks ok though i think that we should eventually change the default of 
>>>> 12frame gop and 200kbit its probably not what most users would want
>>> Does the "eventually" imply that I can commit the patch as is, and
>>> that the defaults can be modified in a follow-up patch?
>>>
>>> If so, would 800kbit and 15 frame GOP be more in line with what users
>>> want? Or should I post to ffmpeg-users and see what is being most
>>> commonly used? :)
>>>
>> 12 is actually much used in MPEG-2 PAL since it's around 25/2 s, 15 is 
>> more used in NTSC (30/2), DVD specs requires the gop not to be > 18, 
>> MPEG-4 should use a much larger gop size though.
> Well, the MPEG-4 codec is used by default, so I would assume it would
> be most interesting to give it a "good" value for MPEG-4 encoding, and
> ignore f.e. the DVD specs. If one wants DVD compliance, one will most
> likely use the -target (pal|ntsc)-dvd anyway. Remains to be seen what
> a "good" GOP size for MPEG-4 would be... :)
> 

It depends on the output format. 'vob', 'mpg' uses mpeg2/mpeg1 respectively.

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