Dropped Frames Explained

[pbmc59]

Hi,
I hate to ask this, I searched for a topic covering this, but may have missed it.
What are dropped frames, and what are the symptoms?
I have captured, encoded and authored three DVDs from D8 tapes so far, and I have the feeling I'm not seeing dropped frames, or it's just I don't know what to look for yet.
I have TMPGenc, capture with Windows Movie Maker II and burn with Sonic MyDVD.
Thanks for your time.......

[Craig Tucker]

For PAL video there are 25 still frames per second (29.97 for ntsc) which make up the moving video image. You can drop the odd frame without it being noticable but if you drop too many you will lose enough of the video information that the video just wont look right. It will not play smoothly and will appear to stutter. I have not used moviemaker to capture so I cannot really comment on that, but all capturing software I have used will report on how many frames have been dropped during a capture.

[Allan55]

Hi,

There is another place where the phrase "drop frame" will appear.

Some time-line editing packages use this phrase because 29.97 frames per second doesn't work very well on a time-line where we want so see our time in hours:minuteseconds. However this is just a display and editing quirk, I've never seen a good package actually drop real frames from a video clip.

Allan

[Craig Tucker]

Hi,

I've never seen a good package actually drop real frames from a video clip.

Allan

Happens all the time, just search the forum for dropped frames. In fact vdub actually intentinally drops the occasional frame to keep the audio in sync. This is to account for the sound card clock and pc clock not being perfectly synced. The odd dropped frame is not noticable whereas the audio going gradually out of sync is very noticable. Now if you are talking about DV rather than analogue capture then yes you should be able to transfer (not capture) dv without dropping any frames.

[scottb721]

I'm running XP with 7200rpm seagate 60Gb HD. 256Mb DDR400 ram.
I used V.dub to capture from my analog camcorder at 480x576 using huffy. My CPU usage is between 16 and 30%.
I defrag the hardrive and only drop about 2 frames during each 10min capture

When I went into Disc Defragmenter and alalysed the HD I saw that the capture files just happen to have the same number of fragments as dropped frames.

In my case, is V-dub dropping frames only because the HD is deciding to frag the file for some reason?

[Allan55]

Hi again,

I certainly won't argue with Mr. Tucker; I doubt I have anywhere near the knowldege of video stuff. I just haven't used vDub for a while and I've rarely/never had audio sync problems with my Hollywood Bridge which captures both audio and video to DV at the same time (I don't have to go thru my audio card).

I agree that an undefragged drive can cause dropped frames as can capturing to your system drive (the swap file is on it as well as other stuff). I never capture to my system drive; I always capture to a second drive that I reformat frequently (faster and easier on the drive than defrag). Also, Scenalyzer seems to have a good buffering scheme. With all this I rarely see a dropped frame.

Regards

Allan