Flushing DV transcode buffer problem

[bhbuckeye]

Hi,
Long time user/lurker...nice site...
I usually only work with DV.AVI files...no/few problems...

However, when I recently tried to work with MPEG I had problem above.

Hooked analog outputs of my Tivo to my canopus advc-100...This gives me DV out right? (firewire into computer)

I set capture settings to convert this to to MPEG2, 720x480 VBR 8000, LPCM 48000 stereo...

Things hum along fine (no dropped frames) for about 30 minutes and then message comes up saying it is flushing buffer--at which time capturing pauses till buffer is empty...resulting in 5 minutes of dropped frames or so and then capturing starts again where the input is now...

How do I get around this?...I've got loads of memory and harddrive space...seem to me I should be able to capture a couple of hours or more easy...

Edit: Using VS9
Thanks in advance

[Ken Veal]

hi
dont think there is a way around the buffer prob, had same touble,
went back to AVI.Forum search will confirm.
Regards Ken

[Ken Berry]

I know the Canopus is hard-wired to transfer DV from an analogue source, but is it also hard-wired to transfer mpeg-2? Is the setting you talked about in the Canopus settings or Video Studio?

If the latter, then depending on your computer resources (basically how powerful your computer is), it is quite normal for Video Studio, sooner or later, to report that the transcode buffer has filled, simply because it is using all computer resources to try to keep up with the digital signal coming into it which is being converted to mpeg-2 on the fly. This is an incredibly resource-intensive process. If it can't quite keep up, then the buffer fills, and VS halts receipt of new signal until such time as it can flush the buffer by recoding all the incoming and buffered signal to mpeg-2. Then it starts again, but in the meantime, you have messy capture and lots of lost frames.

The only options I can think of are to continue to capture in DV and do your conversion to mpeg-2 after any editing. Or else do your captures in smaller segments, i.e. less than the 30 minutes or so it is currently taking the program to capture before reporting its buffer is full...

[bhbuckeye]

As far as I can tell Canopus advc-100 can only convert Analog to DV.

I turned of anti-virus and Spysweep...anything else I can do to get to 2 hours or so? change bit rate?

thanks

[Ken Berry]

My main point, really, (which I suppose in retrospect I didn't really make), is that you are far better off capturing to DV, doing your editing in that, and only then converting it to DVD compliant mpeg-2. If your computer is not up to direct mpeg-2 captures, then don't push it. Many people believe, in any case, that you should not edit mpeg-2 very much, and that you will experience a variety of problems doing so. High quality DV is a much better format to edit, the only downside being that its file size is five times as large as mpeg-2. But if you have the disc space, it is what you should be capturing. Do your edits in it, and only then should you go to Share > Create Video File > DVD, and then Share > Create Disc > DVD.

[heinz-oz]

If your program reports the buffer needs flushing, it needs flushing, nothing anyone can do about this, except making hardware changes to give the PC more grunt. Easiest way out, IMHO, is to capture in shorter segments or to capture to AVI (my preferred) and convert after.

It doesn't matter how powerful you think your PC is, for this problem to occur, there must be a bottleneck somewhere. The PC cannot keep up with writing the stream of data it receives to disk.

[2Dogs]

If I'm reading this right, you're using VS to do direct MPEG-2 capture by feeding in DV from your Canopus device. Seems like a bit of a "round the houses" way to do it, but if you wish to use that workflow, I think that the transcode buffer problem relates to the quality slider setting in the video capture properties.

With my own P4c 2.8, I can't go above a setting of 89%. You can extend the amount of time it takes for the buffer to fill by installing more RAM, but if you have it above a certain value for any given pc, it will fill up with all the resultant bad effects you describe. Other than using a faster pc, the obvious step would be to reduce the quality slider setting. By default, VS will set it at a value that it considers appropriate to your system. Try reducing it a point or two - but note also that there seem to be "sweet spots", whereby some higher settings will not fill the buffer whereas lower ones will.

Check Task Manager to see how many processes are running when you do your video capture. I can get my own system down to 12, including Task Manager, and that seems to be worth at least a few percent on the quality slider.

The next thing, of couse, is how the quality slider setting affects the video picture quality. I can't say that I notice any improvement when going from 89% to 100% in a double-blind test, but I certainly can see a serious drop in quality if capturing with the slider set to 10%.

It does bug me that I can't use 100% with my system, but of course I capture to AVI anyway, and avoid editing MPEG-2 files as far as possible. There is no doubt whatsoever that editing MPEG-2 results in artefacts, especially noticeable at transitions, which you will see if you know they're there! VS does a great job of hiding the artefacts if you step thru edited footage, but a freeware program such as VirtualDub will show them very clearly.

[maddrummer3301]

bhbuckeye,
>>Things hum along fine (no dropped frames) for about 30 minutes

As soon as you said 30 minutes I suspected you had over 1 gig of ram.
(Your system states 1.5gig).

When doing real-time conversion the computer is actively buffering to RAM. When you stop capturing the ram is so fast the buffer is emptied
and the process goes seamlessly. It's so fast emptying the computers ram buffer you don't know it's doing it.
So a 5 or 10 minute capture seems to work nice.
After capturing for 5 minutes and hitting the Stop button the buffer is flushed from RAM, very fast and hardly noticeable.

When you run out of "Real_Physical_Memory (Ram)" the computer then starts the buffering to the harddisk. You can see the difference in speed between the computers ram and the harddisk.
If you have enough ram you can capture for quite a while going from DV to Mpeg2 in real-time.
This is provided you have the "Free" ram to start with and haven't run any other programs that have used up physical ram.

30 Minutes is actually very good for DV to Mpeg2 conversion.

Instead of capturing DV to Mpeg2 conversion if I need to record direct
to Mpeg2 I'll use my "Analog Video Capture Device" and connect the
camcorder up via the s-video connector. I think it gives a nice capture and you can capture the complete video.

Hope this helps,

MD

[bhbuckeye]

Hi and thanks for responses...

Reason I am trying to go this route...

I have a sattelite Tivo unit with no onboard dvd recorder...I believe it's the 40 hour HDD model. every couple of months or so there's a few things on there that we think we would like to keep/just can't bear to delete...(gotta keep from filling this drive up) an SNL, or a maybe an Oprah episode where one of my wife's friends was in audience...etc...silly--I am not making this up--if I don't put this on dvd I am in trouble

I was thinking going mpeg would save/cut me the time of having to render...not really concerned about editing in this case...we can FF on dvd thru commercials pretty quick...

Every few months or so we end up with 4 hours or so and I was just trying to make the whole process quicker...I reroute some cables etc. to do this...

I would normally have no problem upgrading to a Tivo w/dvd, but directv is supposedly going to make some changes this year and I don't want to spend any money till I see how that's going to shake out for me here in Columbus, OH

thanks again...

[GeorgeW]

As mentioned, try lowering the Quality slider towards the middle (if you have it all the way up to 100%).

Regards,
George