[FFmpeg-devel] [RFC] Interlaced material, pix_fmt change, auto-inserted scaler

[Michael Niedermayer]

On Tue, Jul 26, 2011 at 01:46:01PM +0200, Michael Niedermayer wrote:
> On Tue, Jul 26, 2011 at 09:49:09AM +0100, Mark Himsley wrote:
> > On 26/07/11 01:11, Michael Niedermayer wrote:
> >> On Mon, Jul 25, 2011 at 06:12:25PM +0100, Mark Himsley wrote:
> >>> Sorry for a very long rational for a very short patch.
> >>>
> >>> Cutting to the chase: What do you think of the attached patch?
> >>>
> >>>
> >>> Basically: I have been getting some strange colour artefacts when I
> >>> convert from yuv420p to yuv422p on interlaced material.
> >>>
> >>> Here is a demonstration clip:
> >>> http://commondatastorage.googleapis.com/himslm01/976_0003_01.AVI
> >>>
> >>> The clip is an original DV25 clip created in a camera. The important
> >>> part is the first 200 frames where there is a whip-pan across a bright
> >>> green light switch.
> >>>
> >>> If I convert that clip to a 422 format, I've chosen DV50 for ease of
> >>> this demonstration but I have also created IMX30 MPEG 2 video and it
> >>> shows the same issue I'm trying to describe:
> >>>
> >>> ffmpeg -loglevel debug -i 976_0003_01.AVI -vcodec dvvideo -pix_fmt
> >>> yuv422p -acodec pcm_s16le 976_0003_01.DV50.avi
> >>>
> >>> (full output of that command is below)
> >>>
> >>> If I look at the 422 output at field rate (for instance in a video
> >>> editor) then I can see that something is wrong with the chroma.
> >>>
> >>> I think I can also demonstrate that using FFmpeg by using the yadif
> >>> video filter on the original 420 and the new 422 copy:
> >>>
> >>> ffmpeg -loglevel debug -i 976_0003_01.DV50.avi -vframes 200 -vf yadif=1
> >>> -r 50 -f image2 422%04d.png
> >>>
> >>> frame 122 is a good one to compare,
> >>>
> >>> png taken from original footage:
> >>> http://commondatastorage.googleapis.com/himslm01/orig0122.png
> >>>
> >>> png taken from conversion to 422:
> >>> http://commondatastorage.googleapis.com/himslm01/4220122.png
> >>>
> >>> You can see the big difference.
> >>>
> >>>
> >>> But I noticed that if I specifically add an interlaced aware scale in
> >>> the video filter, the chroma is correct.
> >>>
> >>> ffmpeg -loglevel debug -i 976_0003_01.AVI -vcodec dvvideo -pix_fmt
> >>> yuv422p -acodec pcm_s16le -vf scale=0:0:interl=-1 976_0003_01.DV50-vf.avi
> >>>
> >>>
> >>> The attached patch makes scale default to being interlaced aware. Is
> >>> that a bad thing?
> >>>
> >>>
> >>> If you feel this patch will be ok I'll send it again along with updated
> >>> documentation with no training white space.
> >>
> >> it should be ok
> >>
> >> [...]
> >
> > Two patches attached.
> >
> > ffmpeg-scale-default-interlaced-aware.diff: make scale filter default to  
> > interlaced aware scaling & format changing dependent on source frames  
> > interlaced flag
> >
> > ffmpeg-scale-default-interlaced-aware-format.diff: reformat to usual  
> > coding standards
> 
> both applied

but not pushed, due to:

 --- ./tests/ref/vsynth1/dnxhd_1080i    2011-07-14 21:41:40.425374187 +0200
+++ tests/data/fate/vsynth1-dnxhd_1080i 2011-07-26 13:45:49.895749789 +0200
@@ -1,4 +1,4 @@
 34949ea38da2cf6a8406ad600ad95cfa *./tests/data/vsynth1/dnxhd-1080i.mov
 3031875 ./tests/data/vsynth1/dnxhd-1080i.mov
-0c651e840f860592f0d5b66030d9fa32 *./tests/data/dnxhd_1080i.vsynth1.out.yuv
-stddev:    6.29 PSNR: 32.15 MAXDIFF:   64 bytes:   760320/  7603200
+3c3226518a0f56468bf56a6682e31fae *./tests/data/dnxhd_1080i.vsynth1.out.yuv
+stddev:   14.22 PSNR: 25.07 MAXDIFF:  119 bytes:   760320/  7603200
make: *** [fate-vsynth1-dnxhd_1080i] Error 1
make: *** Waiting for unfinished jobs....
--- ./tests/ref/vsynth1/dv  2011-07-11 03:51:36.225253709 +0200
+++ tests/data/fate/vsynth1-dv  2011-07-26 13:45:53.105749789 +0200
@@ -1,8 +1,8 @@
 27ade3031b17214cf81c19cbf70f37d7 *./tests/data/vsynth1/dv.dv
 7200000 ./tests/data/vsynth1/dv.dv
-02ac7cdeab91d4d5621e7ce96dddc498 *./tests/data/dv.vsynth1.out.yuv
-stddev:    6.90 PSNR: 31.34 MAXDIFF:   76 bytes:  7603200/  7603200
+31b3c8f0fa8ae336c561ccdee5738376 *./tests/data/dv.vsynth1.out.yuv
+stddev:   12.83 PSNR: 25.96 MAXDIFF:  125 bytes:  7603200/  7603200
 bd67f2431db160d4bb6dcd791cea6efd *./tests/data/vsynth1/dv411.dv
 7200000 ./tests/data/vsynth1/dv411.dv
-b6640a3a572353f51284acb746eb00c4 *./tests/data/dv.vsynth1.out.yuv
-stddev:   30.76 PSNR: 18.37 MAXDIFF:  205 bytes:  7603200/  7603200
+7baa332c913fc9b65b7b24830acd74e0 *./tests/data/dv.vsynth1.out.yuv
+stddev:   31.72 PSNR: 18.10 MAXDIFF:  206 bytes:  7603200/  7603200
make: *** [fate-vsynth1-dv] Error 1
--- ./tests/ref/vsynth1/dv50    2011-07-11 03:51:36.225253709 +0200
+++ tests/data/fate/vsynth1-dv50    2011-07-26 13:45:53.885749789 +0200
@@ -1,4 +1,4 @@
 26dba84f0ea895b914ef5b333d8394ac *./tests/data/vsynth1/dv50.dv
 14400000 ./tests/data/vsynth1/dv50.dv
-a2ff093e93ffed10f730fa21df02fc50 *./tests/data/dv50.vsynth1.out.yuv
-stddev:    1.72 PSNR: 43.38 MAXDIFF:   29 bytes:  7603200/  7603200
+0f612929578f4955c88690b36a783d79 *./tests/data/dv50.vsynth1.out.yuv
+stddev:   20.25 PSNR: 22.00 MAXDIFF:  224 bytes:  7603200/  7603200


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is dangerous to be right in matters on which the established authorities
are wrong. -- Voltaire
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