2016.01.19. 22:23 keltezéssel, Paul B Mahol írta:
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?
If you mean the pad filter, yes, I will check it.
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