• Status Closed
  • Percent Complete
  • Task Type Patches
  • Category Applications
  • Assigned To No-one
  • Operating System iPod 5G
  • Severity Low
  • Priority Very Low
  • Reported Version Daily build (which?)
  • Due in Version Undecided
  • Due Date Undecided
  • Votes
  • Private
Attached to Project: Rockbox
Opened by Buschel - 2007-09-12
Last edited by preglow - 2007-09-28

FS#7763 - Speed up of video rendering for iPOD Video

Speeding up the lcd_yuv_blit()-function for iPOD Video. Measured with “elephants dream” the fps has gone up from 9.1 to 9.9 fps.

Closed by  preglow
2007-09-28 11:25
Reason for closing:  Accepted

- saved 4 multiplies and 2 substraction
- saved 3 variables
- simplified range-limitation (added 4 shift through this)

Even more speed-up (now “elephants dream” plays at about 10.4fps, which is +15% compared to trunk).

- took over conversion parameters from sansa/gigabeat; these look more reasonable than the former ones
- added some documentation about conversion and constants
- split range-check of RB- and G-components to save 4 shifts (this is faster than only one check with additional shifts)

- in the former code (also in trunk!) the “-16” in the operation (Y’-16) * RGBYFAC was missing
- in trunk code an allowed value (up to 0x3f) of the green component would always lead to boundary check of all components

Your patch would seem to work quite nicely on my 80GB iPod video, now I guess I just have to wait on it being committed to SVN.

Keep up the good work all these little tweaks add up and help to make the iPod ports just that little bit nicer :)


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