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gstreamer/subprojects/gst-plugins-good/ext/jpeg
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Marek Vasut 9a029f016d Revert "jpegdec: only allow conversions from RGB" 
This reverts commit 2aa2477208.
The commit is completely wrong, libjpeg-turbo is perfectly capable
of decoding I420 (YUV) to RGB. The test case provided alongside the
aforementioned commit passes without this revert because it decodes
image of JCS_YCrCb color space, so the new `if (clrspc == JCS_RGB)`
condition is false on that image, and the libjpeg-turbo decoding
does not get used. The real bug is hidden by that commit.

The real problem is in the call order of gst_jpeg_dec_prepare_decode()
and gst_jpeg_dec_negotiate(). The gst_jpeg_dec_prepare_decode() calls
jpeg_start_decompress() which sets up internal state of the libjpeg,
however, neither cinfo.out_color_space nor cinfo.raw_data_out are
set correctly yet. Those two are set up in gst_jpeg_dec_negotiate()
which is called a bit later. Therefore, the real fix is the set up
cinfo.out_color_space and cinfo.raw_data_out before calling
jpeg_start_decompress(). This is however a separate patch.

Fixes: 2aa2477208 ("jpegdec: only allow conversions from RGB")
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1687>
2022-02-13 14:46:31 +01:00
..
gstjpeg.c Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstjpeg.h Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstjpegdec.c Revert "jpegdec: only allow conversions from RGB" 2022-02-13 14:46:31 +01:00
gstjpegdec.h jpegdec: Support libjpeg-turbo colorspace conversion 2021-10-07 12:40:29 +00:00
gstjpegelements.h Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstjpegenc.c Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstjpegenc.h Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstjpegplugin.c Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstsmokedec.c Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstsmokedec.h Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstsmokeenc.c Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
gstsmokeenc.h Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
meson.build Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
README Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
smokecodec.c Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
smokecodec.h Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00
smokeformat.h Move files from gst-plugins-good into the "subprojects/gst-plugins-good/" subdir 2021-09-24 16:13:50 -03:00

README 

The Smoke Codec
---------------

This is a very simple compression algorithm I was toying with when doing a
Java based player. Decoding a JPEG in Java has acceptable speed so this codec
tries to exploit that feature. The algorithm first compares the last and the 
new image and finds all 16x16 blocks that have a squared difference bigger than
a configurable threshold. Then all these blocks are compressed into an NxM JPEG.
The quality of the JPEG is inversely proportional to the number of blocks, this
way, the picture quality degrades with heavy motion scenes but the bitrate stays
more or less constant.
Decoding decompresses the JPEG and then updates the old picture with the new
blocks.


TODO:
----
- make format extensible
- motion vectors
- do some real bitrate control