On Sun, Oct 11, 2015 at 11:07:25PM +0200, Christophe Gisquet wrote: > Hi, > > 2015-10-11 18:20 GMT+02:00 Michael Niedermayer <mich...@niedermayer.cc>: > > On Sun, Oct 11, 2015 at 04:06:05PM +0200, Christophe Gisquet wrote: > >> The functions related to bitstream reading must use the natural zigzag > >> order, and not the one permuted for use in the iDCT. This currently > >> results in bitstreams with 2 issues: > >> - AC coefficients are encoded in an unexpected order; > >> - Incorrect weights are applied in the (de)quantization. > >> > >> This currently can't show up because there's no simple_idct which > >> requires a permutation. > >> > >> With one that does (based on prores'), and using the following source: > >> -f lavfi -i testsrc=s=1920x1080 -vframes 1 -pix_fmt yuv422p10le > >> and encoding to CID 1241 (interlaced 1080p YUV422) using: > >> -vcodec dnxhd -flags +ildct -vb 185M > >> > >> before: stddev: 55.57 PSNR: 61.43 MAXDIFF: 960 > >> after: stddev: 0.35 PSNR:105.45 MAXDIFF: 11 > >> --- > >> libavcodec/dnxhdenc.c | 12 +++++++----- > >> 1 file changed, 7 insertions(+), 5 deletions(-) > > > > breaks: > > ./ffmpeg -f lavfi -i testsrc=s=1920x1080 -vframes 1 -pix_fmt yuv422p > > -vcodec dnxhd -flags +ildct -vb 185M test.mov > > > and thinking about it a bit more (which i should have done earlier) > > i suspect it to break every 8bit case > > the fdct permutes its output if the idct_permutation is set so its > > OK, so that's the issue, and the current dnxhdenc code totally misled me here. > > So, actually, it's the quantize function that applies this, and it's > missing from the 10bits version. > > In the end, I don't think the code really needs all of this (there's > one single scantable...), but that cleanup is not for now. > > I decided to reuse the code from mpegvideo_enc in that matter, so see > the new patch here. > > -- > Christophe
> dnxhdenc.c | 11 ++++++++--- > mpegvideo.h | 3 ++- > mpegvideo_enc.c | 6 +++--- > 3 files changed, 13 insertions(+), 7 deletions(-) > c4ff74009048b80d9e5b7c7639d6c24109edb325 > 0001-mpegvideo-dnxhdenc-permute-10bits-content.patch > From b7e33c1bd9c3645b3b242d336e2e728bbfd4b822 Mon Sep 17 00:00:00 2001 > From: Christophe Gisquet <christophe.gisq...@gmail.com> > Date: Sun, 11 Oct 2015 22:58:21 +0200 > Subject: [PATCH 1/9] mpegvideo: dnxhdenc: permute 10bits content > > Dequant or encoding were trying to reverse a scan that hadn't been > applied... this seems to cause artifacts on the red/cyan edge in ./ffmpeg -f lavfi -i testsrc=s=1920x1080 -vframes 1 -pix_fmt yuv422p -vcodec dnxhd -flags +ildct -vb 185M test.mov [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB The educated differ from the uneducated as much as the living from the dead. -- Aristotle
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