mythbuntu-bugs team mailing list archive

[Phillip Susi <psusi@xxxxxxxxxx>]

mplayer needs to use the modern high resolution posix timers interface
rather than the kludgly old rtc or busy waiting methods for timing.

** Package changed: linux (Ubuntu) => mplayer (Ubuntu)

** Changed in: mplayer (Ubuntu)
   Importance: Undecided => Medium

** Changed in: mplayer (Ubuntu)
       Status: Confirmed => Triaged

** Summary changed:

- rtc: max-user-freq too low for multimedia apps
+ use modern hrtimers

** Changed in: mplayer (Ubuntu)
     Assignee: (unassigned) => Phillip Susi (psusi)

** Description changed:

- Binary package hint: linux-source-2.6.22
- 
- Hi,
- 
- some apps can use the RTC in order to optimize video playback to avoid
- tearing, etc. For MythTV and MPlayer, /dev/rtc/max-user-freq should be
- set to 1024 to enable this functionality. However, it's set to 64 by
- default. MYthTV will fall back on a worse video timing method.
- 
- Here's an excerpt from the MythTV wiki on this matter:
- 
- "If MythTV will be using the RTC to time the display, it will usually
- request a high interrupt frequency, allowing it to time frames more
- precisely. However, unless MythFrontend is a privileged process, the
- highest frequency that it can request by default is 64 Hz. This is
- usually not sufficient for CRT monitors that are often set to a higher
- frequency, usually 85 or 100 Hz, as well as some LCD screens and
- projectors that can accept various frequencies, producing the tearing
- artifacts as mentioned earlier. The most common solution is simply to
- increase the maximum frequency that an unprivileged process can request
- from the RTC."
- 
- IMHO, /dev/rtc/max-user-freq should be set to 1024 by default. I tried
- to set dev/hpet/max-user-freq because HPET seems to be the way to go
- nowadays, but that didn't work. I still had to set /dev/rtc/max-user-
- freq to 1024 to make MythTV work with RTC video timing.
+ Mplayer prefers to use the old /dev/rtc device to generate high
+ resolution interrupts for it to wait on for timing purposes.  This
+ interface can only be used by a single task on the system and is
+ wasteful of cpu and power.  When this is not available, or not
+ configured to allow setting 1024 interrupts per second ( it isn't by
+ default ), it falls back to wasteful busy waiting.  It needs patched to
+ use modern posix timers that can use the modern tickless and HPET kernel
+ features to allow the cpu to remain in deep low power state until the
+ exact time requested.

** Changed in: mplayer (Ubuntu)
   Importance: Medium => Wishlist

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https://bugs.launchpad.net/bugs/139949

Title:
  use modern hrtimers

Status in Mythbuntu, Ubuntu derivative focused upon MythTV:
  Fix Released
Status in “mplayer” package in Ubuntu:
  Triaged

Bug description:
  Mplayer prefers to use the old /dev/rtc device to generate high
  resolution interrupts for it to wait on for timing purposes.  This
  interface can only be used by a single task on the system and is
  wasteful of cpu and power.  When this is not available, or not
  configured to allow setting 1024 interrupts per second ( it isn't by
  default ), it falls back to wasteful busy waiting.  It needs patched
  to use modern posix timers that can use the modern tickless and HPET
  kernel features to allow the cpu to remain in deep low power state
  until the exact time requested.

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