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Bug 722082 - encoder: h264: calculate a better slice_qp_delta in running time
encoder: h264: calculate a better slice_qp_delta in running time
Status: RESOLVED OBSOLETE
Product: GStreamer
Classification: Platform
Component: gstreamer-vaapi
git master
Other Linux
: Normal enhancement
: git master
Assigned To: GStreamer Maintainers
GStreamer Maintainers
Depends on:
Blocks:
 
 
Reported: 2014-01-13 08:27 UTC by Wind Yuan
Modified: 2018-11-03 15:44 UTC
See Also:
GNOME target: ---
GNOME version: ---


Description Wind Yuan 2014-01-13 08:27:58 UTC 
gstvaapi H.264 encoder need set a proper slice_qp_delta in encoding slices. The currently code only set a fixed value. It's better to make slice_qp_delta more flexible in running. some possible options.
1. CQP mode, keep 0.
2. bitrate control mode, need to check the bitrate fluctution. always keep a window size there and compare the summary of last few encoded frame size, if larger than window, set slice_qp_delta > 0 to reduce next frame size. If less than avg, set to < 0 try to fill the window, but make sure init_qp + slice_qp_delta >= min_qp.
3. none rate-control mode, maybe set to 0, or random between [init_qp - n, init_qp + m]. certainly if can consider about quality changes should be much better.
Any suggestions/comments welcome.
Comment 1 Gwenole Beauchesne 2014-06-30 05:33:27 UTC 
The problem is the analysis based on the past frames may not be suitable for the future frames. That's probably why a two-pass encoding mode could be appealing, with some additional heuristics. A more fine-grained option could be worth exploring FEI-based encoding.

Though, this is beyond the scope of 0.5.9 release, defering to a later stage.
Comment 2 GStreamer system administrator 2018-11-03 15:44:26 UTC 
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