0002934: 'Affine' & 'Composite' discrepancies, odd behavior between 'Extract Frame' and rendered output.

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Project

Category

View Status

Date Submitted

Last Update

0002934

Kdenlive

Effects

public

2013-01-10 22:32

2013-02-13 18:06

Reporter

yellow

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

new

Resolution

open

Platform

64 bit

Ubuntu

OS Version

12.10

Product Version

Recent git

Target Version

Fixed in Version

Summary

0002934: 'Affine' & 'Composite' discrepancies, odd behavior between 'Extract Frame' and rendered output.

Description

When using the 'Affine' transition on rec709 h264 video source, extract frame from project monitor color is correct. Rendered output, in this test h264, color is incorrect. Color change suggest from source, appears that maybe a BT601 color matrix conversion is happening with 'Affine' transition on the time line but BT709 in the Project Monitor.

Conversely, using a 'Composite' transition on same rec709 h264 source, extract frame from Project Monitor color is incorrect, but rendered output color matches the source file. Suggesting BT601 color matrix used in Project Monitor but Bt709 on time line for rendered output.

Steps To Reproduce

Open a 1080p 25fps project and add the redblue-rec709.mp4 file to Video Track 2, render out to h264, 2 pass, 25000 bitrate.

The source file redblue-rec709.mp4 is an encode of the enclosed redblue.png source file converted to 4:2:0 with restricted range luma using Avisynth ConvertToYV12(matrix="rec709") and encoded via x264 specifying BT709 primaries, transfer and color matrix. A typical HD h264 video file.

Extract Frame 1 from the Project Monitor as a .png

Sample the color blue and check against color blue in the redblue.png source file and repeat for color red. Sampling needs to be done in the central solid bar through the image which is solid color not gradient.

The r,g,b values should be identical between source png and frame extract png. They were when I tested. See enclosed image redblue_rec709_kden_out.png

Extract Frame 1 of your encoded out h264 via a reliable method not kdenlive as it skews results. I used Avisynth but ffmpeg no doubt will do a 'correct' conversion to RGB and sample color blue and red. Both will be identical to the extracted project monitor frame and initial redblue.png source file.

Now repeat the process but this time add the transparency.png to Video Track 1 and with the 'Affine' transition render to h264 as before and extract frame 1 from the project monitor. Extract a frame from the h264 'Affine' based encode with a reliable YCC to RGB method.

Sample the red and blue again in both files and compare to redblue.png source file. You should see that the project monitor frame extract colors are 'correct' but the frame extracted from the 'Affine' based h264 red and blue are skewed (r=255, g=25, b=0) & blue (r=0, g=15, b=255). See enclosed redblue_rec709_kden_out_avs_affine.png (avs is for avisynth) If I choose to use a BT601 color matrix in Avisynth colors are corrected. So I think the wrong color matrix is being used in the YCC - RGB conversion with 'Affine'

Repeat again but change the 'Affine' for 'Composite'. So the encode out is transparency + original redblue-rec709.mp4 to h264 based on composite transition. Also extract a frame from Project Monitor.

Extract a frame from the h264 'Composite' based encode with a reliable YCC to RGB method.

Compare red and blue in the two extracted frames ie: Project Monitor and rendered h264 based on composite as done previously. You should find the Project Monitor extract is skewed (r=255, g=25, b=1) & blue (r=1, g=15, b=255) but the extract from the rendered output is correct, well near enough. (r=253, g=0, b=0) & blue (r=0, g=0, b=252).

See enclosed "redblue_rec709_kden_out_avs_" affine and composite .png files.

Additional Information

Sorry it's so long winded.

Issue History
Date Modified	Username	Field	Change
2013-01-10 22:32	yellow	New Issue
2013-01-10 22:33	yellow	File Added: chroma_test.zip
2013-02-13 15:58	Senbee	Note Added: 0009259

Notes
(0009259) Senbee (reporter) 2013-02-13 15:58	I confirm the bug. I'm changing all my Affine transitions to Composite + Pan&Zoom in all my projects otherwise rendered videos look very bad.

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