Files
test2/source/blender/imbuf
Richard Antalik bcc56253e2 Fix T95683: FFmpeg seeking is broken
According to information I gathered, ffmpeg seeks internally using DTS
values instead of PTS. In some files DTS and PTS values are offset and
ffmpeg fails to seek correctly to keyframe located before requested PTS.

This issue become evident after hardcoded preseek of 25 frames was
removed and effort went into more precise seeking to improve
performance. It was thought, that this is bug in ffmpeg code, but
after reading some discussions, I don't think it is considered as such
by their developers, see below:
http://ffmpeg.org/pipermail/ffmpeg-devel/2018-March/226354.html
https://trac.ffmpeg.org/ticket/1189

Best solution seems to be to add small preseek value possibly at
detriment of performance, so 3 frames of preseek are applied. Number 3
was chosen experimentally.

Performance impact seems to be insignificant with this change.

Reviewed By: zeddb

Differential Revision: https://developer.blender.org/D15847
2022-10-12 20:10:15 +02:00
..
2022-09-24 10:57:34 -07:00

The following 4 steps to adding a new image format to blender, its
probably easiest to look at the png code for a clean clear example,
animation formats are a bit more complicated but very similar:

Step 1:
create a new file named after the format for example lets say we were
creating an openexr read/writer  use openexr.c
It should contain functions to match the following prototypes:

struct ImBuf *imb_loadopenexr(unsigned char *mem,int size,int flags);
/* Use one of the following depending on what's easier for your file format */
short imb_saveopenexr(struct ImBuf *ibuf, FILE myfile, int flags);
short imb_saveopenexr(struct ImBuf *ibuf, char *myfile, int flags);

/* Used to test if its the correct format
int IMB_is_openexr(void *buf);

Step 2:
Add your hooks to read and write the image format these go in
	writeimage.c and readimage.c  just look at how the others are done

Step 3:
Add in IS_openexr to blender/source/blender/imbuf/IMB_imbuf_types.h
Add in R_openexr to source/blender/makesdna/DNA_scene_types.h

Step 4:
Add your hooks to the gui.
source/blender/src/buttons_scene.c
source/blender/src/toets.c
source/blender/src/writeimage.c

Step 5:
edit the following files:
blender/source/blender/imbuf/intern/util.c
blender/source/blender/src/filesel.c
blender/source/blender/src/screendump.c
and add your extension so that your format gets recognized in the thumbnails.

Step 6:
Alter the build process:
For cmake you need to edit blender/source/blender/imbuf/CMakeLists.txt
and add in your additional files to source_files.
If you have any external library info you will also need to add that
to the various build processes.

Step 7:
Its also good to add your image format to:
makepicstring in blender/source/blender/blenkernel/intern/image.c