Video
Guides > Capturing/Recording > Dropped Frames &
Audio Sync Errors
Article last updated March 7, 2009
This article
outlines the reasons and fixes for the issue of dropped
frames that can occur when capturing or recording video. In
fact, these rules apply to anything in general. Encoding,
capturing, and just any overall poor system performance.
These simple tricks work wonders for improving computer
performance.
What are dropped frames? Well, that's when your
capture card does not take in all the information it is
given. Information is lost, and the video quality is
degraded because of it. Information is now missing when a
frame has been lost or "dropped". The most obvious
side affect of dropped frames is jerky movement during
playback, or a loss of audio sync. The audio sync is
usually caused because video frames are dropped and audio
frames are not.
Identifying
and fixing the dropped frames problem
1. Multi-tasking
and TSR. Video is demanding. Multi-tasking can cause
dropped frames. Either learn to do one thing at a time or
buy an extra system. Close all TSR (terminate, stay
resident) programs (like anti-virus and other items in your
system tray). Also use CTRL-ALT-DEL to launch the
WINDOWS task manager. Shut down tasks that are not needed
(research what an item is if you are unsure ... look it up
using google.com), like printer software and icon managers.
2. LAN and Internet. LAN/Internet simultaneously
accesses many of your system's 65,535 ports and you rarely
know it. Unplug yourself from the network and Internet so
your usage is solely used on the video task at hand.
3. Heat. An overheated system can drop frames. P4
processors will slow themselves up and hard drives will act
erratic when overheated. AMD processors can melt down and/or
deteriorate (many of them have no internal heat safety
protocols like the Intel P4 chips). Be sure your system is
cooled with good fans/heat-syncs and that your room is
well-cooled. Know that 80 degrees Fahrenheit in the room is
not optimum working temperature, try 70-75 if you can run
the A/C or a good fan.
4. Program settings. Is your program setup properly
for capturing? Rarely is the out-of-the-box setting worth
anything. Tweak.
5. Not the card's fault. If a card always dropped,
the manufacturer would have never shipped it. It's on your
end. Figure it out. Quit blaming XYZ's "horrible"
card and then praising ABC's "wonderful" card
because your luck/knowledge changed after replacement. (When
a driver is speeding down the road, nearly running you over,
you don't blame the car - it's the user's fault.) If there
really was a problem, there'd be a recall or update. Have
you checked the Web site for updates? ...And yes, I know
this doesn't always apply, but it does most of the time.
6. Software vs. hardware. If your device is a
software capturing device and not a hardware capturing
device, these issues become even more important. Software
capturing is more demanding on the CPU than hardware
capturing.
7. Slow computers. P4 or AMD+ systems can do great.
PIII and below is asking for trouble, especially users
operating off the stripped-down Duron and Celeron
processors.
8. Computers are like humans. They need rest too.
Reset your system before giving it a hearty video workout.
I'm still amazed at the number of people that run the
computer for weeks on end without rebooting and wonder why
it's acting up. Because of the way Windows works, you lose
resources after time, especially opening/closing programs.
They never truly close. Maybe even consider letting it stay
powered down for an hour or so before using for captures or
encodes (as it helps to minimize heat too).
9. VHS source. Garbage in, garbage out. It's that
easy. Often, VHS and VHS-C tapes can cause your system to
drop frames. This is usually confined to old tapes that have
seen better days, but it can also apply to newer tapes. The
information being fed into your video card is corrupt, and
it will throw off your system. Unfortunately, there is no
fix for this. A TBC (time-base corrector) may correct the
issues, but even then, that is not fool-proof. The number of
frames dropped for this reason should be a rather small
number (maybe 10 per hour) and will probably happen close
together because of a bad spot on the tape. It may also
help to rewind and fast forward the tape a few times, then
try again.
10. Check your hard drive settings. (For WinNT/2K/XP:
right-click on MyComputer-> Properties-> Hardware->
DeviceManager -> IDE-> Primary IDE channel ->
Advanced Settings-> Current Transfer Mode) and (For
Win95/98/ME: right-click on MyComputer-> Properties->
DeviceManager-> DiskDrives-> IDE-> Properties).
Your system should be set on ULTRA DMA or DMA. Note: Some
Ultra ATA cards (example: Promise card that comes with
Western Digital drives) will not show DMA as an option, but
the feature is turned on.
11. Hard drive usage. Defrag your hard drive on a
regular basis. And use a dedicated hard drive for capturing
(meaning a physically separate drive, not just a partition).
Capturing to the same drive where your OS is housed can
cause conflicts as that drive is always being used by the
Windows or Apple swap files. You want to use a drive that is
not doing anything else at all. RAID drives may or may not
help, and there are reports that both support and reject the
use of RAID for video.
12. CPU usage. If you are using an NT based OS, like
Windows NT/2K/XP, or an Apple, check to make sure the CPU
usage is not max'ing out. If so, that may mean your system
is too slow, improperly configured, or that you codec is too
demanding on your system. It cannot keep up, and hence drops
frames. Non-NT systems, like Windows 95/98/ME, can use
Norton System Doctor to monitor usage.
13. Capture software and codecs. In most cases, the
software that comes with your card will work. It is the
software supported by the card, and what was tested to give
the optimal results. However, other alternatives include
VirtualDub, VirtualVCR, PowerVCR, iuVCR, AVI_IO, WinDVR, and
NeoDVD4... just to name a few. Try a freebie or a trial
edition of any of these packages to see if you can get
better results. If capturing AVI, consider the HuffyUV codec
or an MJPEG codec. Capturing MPEG1 or MPEG2 works great on
some cards, but not all. Not all cards will cooperate with
all software and all codecs, at least from a dropped-frames
point-of-view.
14. Desktop settings. Is your computer system set to
use a 1600x1200 resolution at 32-bit color? If so, that may
too much for your system to handle, in conjunction with
capturing. Try 16-bit or 24-bit color with 1024x768 desktop.
This error is normally found with on-board video cards used
jointly with a cheap capture card. Change your overlay
settings, and try it both with and without overlay
activated.
15. Sound cards. It appears that some sound cards can
cause you to drop frames. Typically confined to ISA
soundcards, cheap PCI soundcards, and onboard sound (your
soundcard is part of your motherboard). This is not a common
problem, but has been known to happen.
16. BIOS settings. Some systems have BIOS settings
that can adversely affect capturing. One user has stated
that turning off FSB SpreadSpectrum on an Asus A7N8X-E
motherboard corrected his capture issues. Be sure to read
the manual that came with your motherboard or find
information online.
17. Memory/RAM. Although less common, RAM can be a
determining factor on video. A minimum of 512MB is
suggested. The minimum is about 256-384 depending on how
your system system acts. Anything over 1GB is pretty much
wasted, and that full 1GB will never be used anyway ... in
fact the full 512MB may not be needed for simple capturing
application.
18. Preview Window. Do not make the video preview
window full screen. Leave it at a relatively average size
(no more than half the monitor size). Otherwise the system
will be forced to allocate more resources to preview rather
than the more-important recording task.
19. Hard drive cache. Another site visitor suggested
this fixed his dropped frames problem. In Windows XP, go to
Device Manager, click on Disk Drive/Properties/Policies/...
and check the "Enable Write Cache" box if it is
not already checked.
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