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For interlaced jpeg, gst_jpeg_dec_decode_direct() is called twice, once for each field. In this case, stride[n] is plane_stride[n] * 2 to ensure that only every other line is written. So the loop must stop at height / num_fields. If the frame is really interlaced then continuing beyound this, is not harmful, because jpeg_read_raw_data() will do nothing and return 0, so am info message is printed. However, if the frame is not actually interlaced, just misdetected as interlaced then there is still data available from the second half of the frame. Now line[0][j] is set to the scratch buffer. If the scratch buffer is not allocated (because the height is a multiple of v_samp[0] * DCTSIZE) then the result is a segfault due to a null-pointer dereference. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4696> |
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| .. | ||
| gstjpeg.c | ||
| gstjpeg.h | ||
| gstjpegdec.c | ||
| gstjpegdec.h | ||
| gstjpegelements.h | ||
| gstjpegenc.c | ||
| gstjpegenc.h | ||
| gstjpegplugin.c | ||
| gstsmokedec.c | ||
| gstsmokedec.h | ||
| gstsmokeenc.c | ||
| gstsmokeenc.h | ||
| meson.build | ||
| README | ||
| smokecodec.c | ||
| smokecodec.h | ||
| smokeformat.h | ||
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