How many dropped frames is too many?

[The Stinger]

Okay, I want to know how many dropped frames is too many? I capture a 30 min program and drop anywhere from 8 to 20 frames in that time frame. Now I have gone over every solution I can think of, defrag, DMA, and I still drop around the same. Is this too many dropped frames?

[WeBe]

In my opinion even 1 dropped frame is 1 too many.

If you're trying to capture from an analogue source and you have newer hardware, try to use Amcap. Download wdmmiscutils2.7.2.zip from sourceforge.net.

This small utility uses the new WDM-drivers (Windows Driver Model) with Direct Show. Needs less performance of your system.

Worked great for me!

Wim.

[dgraham]

1.

[mkelley]

Yep, 1.

I have Premiere set to stop if any dropped frames. Every now and then I get a frame drop (most likely due to power spikes) and I restart my capture and edit the pieces together.

After capturing hundreds of hours without dropped frames I truly believe no one should settle for less.

[Gazorgan]

1

The only time I drop frames is when I pause and resume capture (say at a commercial). Needless to say I edit out commercials in VDUB. My card uses the BTWin chipset, so it's all software. I use IUVcr, clunky but works fine.

[HillJack]

I usually drop 26 frames per hour of captured video. It's never affected the final product in any way/shape/form, so I'm perfectly content with it. I'd rather spend my time tweaking the quality of the final product (SVCD in my case) than worrying about a couple dropped frames.

[gilhoy]

1

The only time I drop frames is when I pause and resume capture (say at a commercial). Needless to say I edit out commercials in VDUB. My card uses the BTWin chipset, so it's all software. I use IUVcr, clunky but works fine.

Interesting.
Is there any particular reason you edit out the commercials while the file is an AVI?
I ask because I usually take out the commercials after i convert to MPEG,
to keep as much hard drive space empty as possible.

[drewson99]

my reasons for editing AVI first is Vdub is much easier to cut chunks out of than cutting up mpeg with tmpgenc, and in addition, editing before encoding results in better audio sync. too many cuts and splices after encoding can screw up the sync.

[mkelley]

[quote="gilhoy"]

1

I ask because I usually take out the commercials after i convert to MPEG,
to keep as much hard drive space empty as possible.

Maybe it's because I'm still ill, but this doesn't make sense to me. Why would editing *after* you convert to MPEG save space? If you edit the AVI first and then convert the edited file to MPEG and then erase the AVI you have the most disk space possible available.

In any case, disk space is kind of a moot issue nowadays, with 120gb going for less than $100. If you find yourself low on space, just buy another drive (I'm eyeing the new 160gb drives but need them to get under $150 before they'll tempt me -- I predict another three to six months).

[uxbridge]

that number of dropped frames seems too high.
Assuming you are running up to 70% CPU utilisation you can loose batch of frames (8-to-20) due to applications in your PC becoming suddenly active. As an example the Antivirus, or the AIM client once you are not on the internet, or one of the many that are loaded at startup and you might even not know. AIM did this to my captures.
Try killing all the unneeded applications including the Antivirus while you capture.

Despite what many people will tell you, zero can not always be achieved. As an example if your video card does not handle stereo and you are therefore connecting your audio output directly to the audio card input, then you'll get some dropped frames, in the ratio of 1 or 2 every hour, simply because the clocks of the audio and the video are not the same, and the capture application syncronises them the only way it can, dropping or adding frames. Vdub does that. Note that Vdub simply tells you about "dropped" frames but sometimes what it does is simply duplicating, therefore "adding" frames.

[mkelley]

uxbridge,

I'm not sure I buy your explanation about dropping frames -- for one thing, the very nature of NTSC means it "drops" frames in order to sync with time code. That has *nothing* to do with dropped frames being reported in the Premiere capture.

I can't speak for other capture applications that may be talking about dropping frames when they are talking about NTSC coding, but I do know this is the way Premiere works -- it only reports dropped frames if frames are actually missing in the capture.

You ought to be able to achieve zero dropped frames using the latest WDM drivers on even a somewhat slower system, particular if you're capturing to a separate video drive (which you should be doing). As I mentioned earlier, I've captured hundreds of hours of video without any dropped frames, on a wide variety of systems. No one should settle for less.

[uxbridge]

mkelley
you talking about software and Premiere.

All what I am saying is that video card and audio card have surely slightly different clock (hardware problem, nothing to do with any capture application) therefore sooner or later, even if you have a perfect capture, a frame has to be dropped or inserted to maintain a certain sync.
This is typical clock problem in any system, (jittering) ranging from your PC to the fibre optic line that ensures phone calls between US and Europe.

Apart from this jittering problem, there is no reason for dropping any frames if CPU utilisation is maintained at a decent level.

If you have audio capture and video capture in a single card, that is not so common if you want stereo audio, but is definitely possible, then the clock is obviously the same, so you'll definitely have zero dropped frames with whatever application, Premiere or Vdub.

[wwaag]

Do yourself a favor--get an ADVC-100. Result--0 frames lost. Plus AV is always in synch--even for long captures. Plus you can do other things on your computer while capturing. There must a reason its the top-rated capture device (at least the last time I looked).

wwaag

just looked--it's still the top rated.

[The Stinger]

Okay so I tried Amcap and it worked great, no dropped frames. But now after encoding to Mpeg2 I notice that the audio is out of sync. And the funny thing is that it looks as if it gets more and more out of sync as the mpeg plays. This is getting frustrating. Do I take the 0 dropped frames with the headache of sync issues or do I take a few dropped frames with the audio in sync.

Let me know guys...

[mkelley]

wwaag is on the right track -- the first thing you need to do is make sure you're using a top quality capture device. Best is to capture through firewire, as USB/PCI have issues pushing that much information through that fast and in sync.

I use the Hollywood Bridge for all analog captures, as it translates into firewire. All DV goes straight through to firewire. Firewire card is top-rated (also important) Pyro. None of this is very expensive but you need to be prepared to spend at least two to three hundred to capture analog.

You must also use a robust OS -- one of the NT flavors (NT, W2K, XP) work best. A dedicated video drive (7200 rpm or higher) is a must as well -- they are also cheap nowadays (less than $100 for 120gig). More memory the better, but I wouldn't try this without at least 256mb (512 or more would be comfortable).

Can you capture successfully with less machine? Of course, and a lot of people do, but I do promise you one thing: if you follow the above you will capture with no dropped frames or other problems. Introducing one or more variables (no dedicated drive, wrong OS, bad capture card) just makes life extremely tough.

[mkelley]

Oh, I should add one more thing -- if you are judging audio sync by playing MPEGs with software on the PC, I wouldn't put too much stock in that. There are a lot of issues here, but suffice it to say this just isn't an accurate test. To give you an example, when I backed up one of my Star Trek series disks and played the ripped footage the video and audio were also out of sync (but synced fine when authored).

Your footage may well be just fine but the only way to know for sure is to burn a DVD.

[Blkout]

I usually drop 26 frames per hour of captured video. It's never affected the final product in any way/shape/form, so I'm perfectly content with it. I'd rather spend my time tweaking the quality of the final product (SVCD in my case) than worrying about a couple dropped frames.

Agreed, and I'll go ahead and call anyone an idiot for recapturing for 1 dropped frame. You can't even see 1 dropped frame, the only time you would notice dropped frames is if there was were multiple dropped frames in the same time period. When you start to imagine capturing 1000's of frames of video and only dropping a few frames, its simply STUPID to go back and capture again, you'll never see the difference.

I have had some captures from poor VHS tapes that would drop around 120 frames in a 1 hour show. You can't even see the difference with that many. Since I bought a TBC, I rarely get more than 5-6 dropped frames with 2-3 being the average in a 2 hour capture but there is no way I would go back and recapture for that small amount, there isn't a person on this Earth who could tell the difference.

Some of you people telling this guy that 1 dropped frame is too many and to recapture need to have your head examined.

[mkelley]

No, but you're missing the point. The point is that 1 dropped frame IS too many, since it takes so little nowadays to get a perfect capture why settle for less?

Dropping frames may be endemic and indicative of other problems, and I certainly wouldn't settle for it. It's like saying that just because your car only leaks a quart of oil every couple of months it's okay. It's not okay, and you should get your system working right.

[Rond66]

Play with all your video parameters .. It might help

This should enlighten you guys who are having trouble with dropped frames and audio sync.

http://www.network54.com/Hide/Forum/thread?forumid=70438&messageid=992892738&lp=1054505219

[dcsos]

Depends on what you're doing because in ANIMATION you can see the dropped frames easier:-)

STINGER...I too like AMCAP
try making the MPEG you capture less fat- rather than going back to
the application that drops frames-Maybe you're capturing to much data ...and essential could scale back on QUALITY without repercussion...
Also investigate whether its only a playback issue...
as sometimes MPEG-2 can fail to play in sync due to computer speed bottleneck issue, and its just the display that is out of sync on what is essentially a good file (of course you do want to play it on that same desktop in sync -so If this file is the final product -ignore this comment-if the file is fine but you're gonna bring it into a program to author with..youre still ok)

[dcsos]

Depends on what you're doing because in ANIMATION you can see the dropped frames easier:-)

STINGER...I too like AMCAP
try making the file you capture less fat- rather than going back to
the application that drops frames-Maybe you're capturing to much data ...and essential could scale back on QUALITY without repercussion...
Also investigate whether its only a playback issue...
as sometimes MPEG-2 can fail to play in sync due to computer speed bottleneck issue, and its just the display that is out of sync on what is essentially a good file (of course you do want to play it on that same desktop in sync -so If this file is the final product -ignore this comment-if the file is fine but you're gonna bring it into a program to author with..youre still ok)

[Blkout]

And I'll repeat this one more time, NONE of you can see one dropped frame. 10 dropped frames in a 1 second period, ok, I'll go with that, but not 1 dropped frame.

And its not easy to get 0 dropped frames for many people, too many factors involved, there is no sense in telling someone that they should recapture over 1 dropped frame. As for the car leaking oil analogy, no not quite, its more like if you car makes 600 horsepower today but only makes 599 horsepower tomorrow, who give a rat's ass? You'll never know the difference!

[mkelley]

Nope, you're wrong -- it is very easy to get zero dropped frames IF you are willing to do some commonsense things.

Besides, if your car suddenly got less horsepower because it was backfiring every now and then it WOULD be a big deal.

But if you're happy, don't worry about it. The original poster asked a question, we expressed our opinion and so did you.

[Blkout]

Nope, you're wrong -- it is very easy to get zero dropped frames IF you are willing to do some commonsense things.

Besides, if your car suddenly got less horsepower because it was backfiring every now and then it WOULD be a big deal.

But if you're happy, don't worry about it. The original poster asked a question, we expressed our opinion and so did you.

Its ok if you can't admit your wrong, most people can't. And losing one HP would not cause backfiring, losing one HP could be the difference in a 1 degree temperature change in the inlet air. The point is that you can't see 1 frame dropped, no one can. Your being completely stupid if you actually recapture your video's over 1 dropped frame.

And yep, I'm happy, I'm not a nutcase which is far more than I can say for some of you guys.

[rhegedus]

When I was capturing with a Hauppauge WinTV PCI card, I thought nothing of getting say 1 dropped frame every minute since 1 out of 1500 (25fps) was not noticeable especially if the audio was locked to the video. It wasn't noticeable on playback so why make a fuss?

Now that I've got an ADVC-100, I stop the capture for 1 dropped frame even after an hour (usually because I try to access the capture drive or scroll too quick in Internet explorer - why does it do that? ).

So, I think the answer to the question is dependant on your set up and the level at which dropped frames become noticeable. For the purists, 1 is 1 too many, but those with lesser set ups will be willing to accept a few.

[cplevel42]

Blkout it is NOT fair to call these people "nut cases" just because they don't share your opinion! It shows a real lack of respect.

I think rhegedus said it well.

So, I think the answer to the question is dependant on your set up and the level at which dropped frames become noticeable. For the purists, 1 is 1 too many, but those with lesser set ups will be willing to accept a few.

Plain and simple though, dropped frames can be avoided if the system is configured correctly all of the software is configured correctly, and there are no hardware problems or conflicts. Last month I was having a few dropped frames per minute on my P4 2.8 ghz System with 128 MB ATI AIW 9700 pro vid card. I was capturing analog through the ATI direct tp mpeg2. I tried everything I could think of, but no luck. I then decided to do a fresh reformat and reinstall of XP. Well, I don't know why, but it did the trick. No dropped frames now, not audio problems. There was an underlying problem in the registry or OS. Personally, I'm not happy to accept a few dropped frames. If I had a p3 500 ghz and was trying to transcode to mpeg2, then maybe that would be a different story.

[Sulik]

Seeing dropped frames depends very much on the content. You WILL notice a single dropped frame on a scrolling news ticker (CNN, CNBC etc), but you probably won't notice even 5% frame drop on film material (though it's a bit more noticeable with PAL).

To everyone who deinterlaces, you're dropping 50% of frames right there unless your source is progressive (unlikely for TV content).
If you're capturing a FILM source from NTSC TV, you're dropping 20% of frames already (fields are repeated), but you can't easily see that.

If you're playing back a file on your PC, the decoder will probably drop frames very easily as well (the display Vsync is never perfectly in sync with the 59.94 or 50Hz referesh of the source, and again you can see these on a scrolling news ticker).

Restarting a capture because you dropped one frame in a hour means that you probably have too much time on your hands, but hey no dropped frames is better than 1, right ?

Personally, I consider 1 dropped frames every 10 minutes more than acceptable (why bother if you can't see the difference ?). Note that this is 1 out of 17982 frames on NTSC (0.00556%). Things like a/v sync and interlaced encode quality is more important to me than dropping a frame every now and then.

[Blkout]

Seeing dropped frames depends very much on the content. You WILL notice a single dropped frame on a scrolling news ticker (CNN, CNBC etc), but you probably won't notice even 5% frame drop on film material (though it's a bit more noticeable with PAL).

To everyone who deinterlaces, you're dropping 50% of frames right there unless your source is progressive (unlikely for TV content).
If you're capturing a FILM source from NTSC TV, you're dropping 20% of frames already (fields are repeated), but you can't easily see that.

If you're playing back a file on your PC, the decoder will probably drop frames very easily as well (the display Vsync is never perfectly in sync with the 59.94 or 50Hz referesh of the source, and again you can see these on a scrolling news ticker).

Restarting a capture because you dropped one frame in a hour means that you probably have too much time on your hands, but hey no dropped frames is better than 1, right ?

Personally, I consider 1 dropped frames every 10 minutes more than acceptable (why bother if you can't see the difference ?). Note that this is 1 out of 17982 frames on NTSC (0.00556%). Things like a/v sync and interlaced encode quality is more important to me than dropping a frame every now and then.

Thank you sir, glad to see there are some people here who have some common sense.

[gf]

I tried a piece of software that FILLS IN dropped frames, and it looked pretty good. So the next thing I did was take a divx video at 15 fps and converted to 29.97 and looked reallllllllll smooooth. If anyone is interested it is called Dynapel motion perfect.

http://www.dynapel.com/com/private/mp_overview.htm

It works only with avi files.

Steve

[Will Hay]

Seeing dropped frames depends very much on the content.

I can't believe it's taken this long for someone to point out this excellent point.
The level of dropped frames is more than likely as a result of the source.
Even if you feel you have a finely tuned system and you still drop frames then I'm sorry, you will never truly identify the source of the problem.
I captured 147 minutes of VHS footage yesterday, and over the course of the capture if I remember correctly I lost 17 frames.
Let me put that into persective; that's 17 lost frames from 220,500.
Fine for me, not for others
If you need to re-capture for one lost frame then okay, but I'll pay you one million pounds, sorry one million dollars, to come around to my house and show me where I lost each frame
As for the engine oil analogy I think it's more a case of:
You put a gallon in and a day later there's a tiny, infinitesimal amount missing.
Now, you know your car is fine and the question you feel you need to answer is did it leak (even though you can't find any trace) or was it used by the engine during the five minute journey you just took?
You know if you take the engine apart and tune, upgrade whatever you can reduce the loss, but at what time and cost?
Each to his own
Will