aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/vp9_parser.c
diff options
context:
space:
mode:
authorAman Gupta <aman@tmm1.net>2016-01-08 19:01:22 -0800
committerClément Bœsch <u@pkh.me>2016-01-14 22:41:41 +0100
commit5c041e2cccc1e09321f0be729364eb70411b6ce1 (patch)
tree8638b555eb7f649332643eb5fdb587d663f53241 /libavcodec/vp9_parser.c
parentd6f1abe9ce08279e6e3f90a80724fcef7a2ab673 (diff)
downloadffmpeg-5c041e2cccc1e09321f0be729364eb70411b6ce1.tar.gz
lavc/ccaption_dec: implement real_time option
This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
Diffstat (limited to 'libavcodec/vp9_parser.c')
0 files changed, 0 insertions, 0 deletions