On 02/06/2021 08:51 PM, Carl Eugen Hoyos wrote:
Am So., 7. Feb. 2021 um 01:34 Uhr schrieb Mark Filipak (ffmpeg)
<markfili...@bog.us>:
[decoder] --> [filters] --> [codecs] --> [encoder]
This looks wrong / misleading.
There is a transcoding pipeline:
demuxer -> decoder -> filter -> encoder -> muxer
And there are formats, codecs, filters, devices (and more) as
part of the FFmpeg project.
My question is:
How are decoder.output and encoder.input structured?
Yes, I know that filters can reformat the video, deinterlace, stack fields, etc.
I have been assuming that the structure is frames of pixels like this:
pixel[0,0] pixel[1,0] ... pixel[in_w-1,0] pixel[0,1] pixel[1,1] ...
pixel[in_w-1,in_h-1]
(The usual style is that rows come first, than columns.)
Thanks (not x,y, eh?). Okay, then this:
pixel[0,0] pixel[0,1] ... pixel[0,in_w-1] pixel[1,0] pixel[1,1] ...
pixel[in_h-1,in_w-1]
In other words, raw video frames with lines abutted end-to-end
In abstract terms, this is of course correct, but note that planar and
packed pix_fmts exist, see libavutil/pixfmt.h, lines and frames are
often padded for performance reasons.
Okay, thanks.
(i.e. not deinterlaced).
I may misunderstand but I believe this part makes no sense
in above sentence.
Carl Eugen
"not deinterlaced" == not this:
pixel[0,0] pixel[0,1] ... pixel[0,in_w-1] pixel[2,0] pixel[2,1] ... pixel[in_h-2,in_w-1] ...
pixel[1,0] pixel[1,1] ... pixel[1,in_w-1] pixel[3,0] pixel[3,1] ... pixel[in_h-1,in_w-1]
and, I should add, not in macroblocks in slices.
The reason I ask is that it seems to me that some of the documentation assumes that readers already
know this.
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