On 1/19/16, Bodecs Bela <bode...@vivanet.hu> wrote: > > > 2016.01.19. 21:42 keltezessel, Paul B Mahol irta: >> On 1/19/16, wm4 <nfx...@googlemail.com> wrote: >>> On Tue, 19 Jan 2016 19:00:18 +0100 >>> Bodecs Bela <bode...@vivanet.hu> wrote: >>> >>>> 2016.01.19. 16:53 keltezessel, Carl Eugen Hoyos irta: >>>>> Bodecs Bela <bodecsb <at> vivanet.hu> writes: >>>>> >>>>>> To retain the current behaviour and not to break any >>>>>> earlier app, a new config parameter has been introduced. >>>>> Is the current behaviour useful or do you consider it a bug? >>>> First I thought that it was a bug, but I borrowed an idea from >>>> vf_overlay filter, where there is a very same config parameter causing a >>>> very similar behaviour distinction on expression evaluation. >>>> I will soon post a patch to vf_overlay where there was really a bug in >>>> this behaviour. >>> I think it's actually a bug. From what I can tell libavfilter's design >>> doesn't actually support mid-stream reconfiguration, although it >>> happens to work in some cases? >> It appears it's undocumented feature. Filter which changes parameters just >> calls >> avfilter_config_links(). >> >> But not all filter have been tested with this in mind. > Working with mpeg-ts streams this feature is very usefull. > I have tested vf_scale and vf_overlay, both of them work well now. > This is the scenario where I use them: > You have an mpeg-ts incoming stream and you transcode it to hls with a > scaled down resolution. > The incoming stream has constant PAL width and height but the aspect > ratio regularly changes between 4/3 and 16/9 in the middle of the stream. > But you want to create a 16/9 output with constant width/height > regardless of incoming aspect ratio. In the 4/3 case you put black bars > to both sides of screen. > With my two recent patch - regarding vf_scale and vf_overlay - it is > possible. > Cascade the vf_scale and the vf_overlay filters. > First you create a fix height but variable width output with vf_scale > and than you overlay its output onto a fixed sized 16/9 black > background, positioned dynamically to the center by vf_overlay. > In case of incoming 16/9 a.r., the whole background will be covered by > the usefull content and in case of 4/3 a.r. the usefull content only > partially will cover the black background. > These options were almost ready in these filters. > (I know the padding filter would do the same job, but it lacks a dynamic > frame-by-frame pad sizing feature)
Willing to write patch for it? _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
