[Ffmpeg-devel] Differences between mencoder and ffmpegwhenencoding using x264

Måns Rullgård mru
Sat Feb 25 23:32:09 CET 2006

Michael Niedermayer <michaelni at gmx.at> writes:

> Hi
> On Tue, Feb 21, 2006 at 07:51:53PM +0000, M?ns Rullg?rd wrote:
>> Robert Swain <robert.swain at gmail.com> writes:
>> > In my opinion the defaults system should be altered such that
>> > defaults can be specified for each codec. Maybe inheriting defaults
>> > from elsewhere and overwriting some as required. Defaults should
>> > also be consolidated as they're all over the place (in the code) at
>> > the moment.
>> >
>> > This is all my lowly opinion. :) The big guns might disagree.
>> > (Michael? Loren? Mans? ...Rich? etc :) )
>> I agree.  The problem right now is that avcodec_get_context_defaults()
>> doesn't know which codec the context is intended for.  I suggest we
>> create a new avcodec_get_context_defaults2(), or whatever, taking an
>> AVCodec as an argument, and doing the same as the present
>> avcodec_get_context_defaults, then fetching overrides from the codec.
>> The per-codec defaults could be supplied either by means of a pointer
>> to a function that when called filled in various values, or perhaps
>> somehow using the AVOption stuff.
>> Is this a bad idea for some reason I haven't thought of?
> the idea sounds good, so if noone has a better one, feel free to
> implement that ...

I started looking at this.  The libavcodec side of it is easy enough.
The problem is making ffmpeg.c use it.  More specifically, it sets all
the parameters in AVCodecContext before deciding which codec to use.
I'd appreciate if someone with better knowledge of ffmpeg.c could give
me a few hints on how to best proceed.

M?ns Rullg?rd
mru at inprovide.com

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