[FFmpeg-user] Setting up a watch folder to encode adaptive bit rate videos

[James Darnley]

On 2015-11-02 12:12, Moritz Barsnick wrote:
> On Sat, Oct 31, 2015 at 20:36:54 +0100, Henk D. Schoneveld wrote:
>> On 30 Oct 2015, at 03:40, Joel Lopez <badassmexican at gmail.com> wrote:
>>> 1.  Single or 2-pass encoding?  I'm reading quality isn't affected
>>> much and that it may be possible to have aligned key frames with
>>> either one.  What do you guys do?
>> 2-pass in my opinion only makes sense when the resulting file has to be stored max-quality to finite storage medium. CD/DVD etc.
>> Do some testing and look what % is saved and relate to the extra time/energy invested in that 2nd pass. 
> 
> I think the point was to use two-pass encoding in order to use the
> intermediate analysis file for various second-pass conversions
> (resolutions, qualities), so that those would result in the same key
> frame locations. This was suggested on "the net" somewhere (Wowza?). I
> neither know whether it is valid to do the second pass with differing
> resolutions, nor whether the key frame locations are absolutely
> determined by the first pass. (Does the first pass analysis determine
> those positions?)

libx264 definitely supports changing resolution between first and later
passes.  It also determines frame types in the first pass.


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