[x264-devel] Optimized multiple rendition encoding

[Eran Kornblau]

> -----Original Message-----
> From: x264-devel [mailto:x264-devel-bounces at videolan.org] On Behalf Of BugMaster
> Sent: Saturday, November 12, 2016 10:36 AM
> To: Mailing list for x264 developers <x264-devel at videolan.org>
> Subject: Re: [x264-devel] Optimized multiple rendition encoding
> 
> On Sat, 12 Nov 2016 07:32:59 +0000, Eran Kornblau wrote:
> 
> > Thanks for your reply! However, as far as I know, 2 pass is about 50% 
> > slower than 1 pass. So if the highest rendition (which is the heaviest 
> > to transcode) will be transcoded with 2 pass, the whole process will 
> > probably take more time than it does now. To put it differently - I 
> > don't think the speed gain in the lower transcodes will compensate for 
> > that.
> > Yes, I may get higher quality thanks to the 2 pass, but my goal here 
> > is to shorten the transcoding time/reduce the resource usage.
> 
> If you currently use 1-pass ABR for your encodings you still can use this method. Only difference would be that you would use result of 1-st pass (which should be done with `--pass 1 --slow-firstpass`) as end result for this bitrate. This way you will make same number of passes (bitrates) as you currently do and N-1 of them wouldn't need lookahead (slicetype decisions, AQ, MBTree) at the little cost of IO (writting/reading stats-files) and probably would have better quality then simple 1-pass ABR for all.
>
That sounds awesome, I'll try it out, thanks!
Do you have some rough estimate on the performance gain for the 2..N renditions ?

> _______________________________________________
> x264-devel mailing list
> x264-devel at videolan.org
> https://mailman.videolan.org/listinfo/x264-devel
>