Random Thoughts: Why can't PCI capture cards keep sync ...

[FulciLives]

Hello

I was just thinking ...

We all prefer (for the most part) to capture an AVI file using HuffyUV or the PICVideo MJPEG using a PCI TV tuner type capture card ... or something like the ATI AIW which can be AGP but basically allows for the same thing.

BUT the problem that so many of us experience ... at least from time to time ... is audio sync.

So I was thinking ...

I remember long ago before I ever got involved with computer digital video that there were MJPEG hardware encoder cards for capturing.

So ...

How hard would it be to make such a card that has NOT only hardware MJPEG encoding but also some sort of built-in audio hardware encoding chip for capturing the audio and of course some sort of device built-in that would "regulate" the two to insure A/V sync. I mean I've always heard that the problem is that the audio card and the video card are using different timer settings blah blah blah because they are two different, seperate pieces of equipment in the PC.

In fact it would seem to me that you might not even need the MJPEG hardware part but just some sort of audio hardware chip that could somehow sync with the incomming video. If it could be done this way then you could use ANY codec for the video that you wanted too ... not just MJPEG.

Now wouldn't that be something YOU would want to buy?

Right now the only thing I can think of that comes close to this is the Canopus ADVC-100 and the DataVideo DAC-100

However these devices capture to DV AVI using a DV hardware encoding solution and we all know that DV is far from the perfect codec. It is mostly a necesarry evil if you need to do EXTENSIVE editing but for most captures where you will be doing simple CUT editing all you really need is VirtualDub which can use HuffyUV and MJPEG etc.

My point is I would run out right now and buy the ADVC-100 or DAC-100 if I was OK with DV but I'm not so sure I am because of some of the image problems with the DV format (such as the fact that it doesn't use 4:2:2 color sampling etc.)

So I want to see a similiar solution but either one that uses hardware MJPEG of high quality (like the PICVideo on the 20 or 19 quality setting) or one that even better yet allows software VIDEO encoding but hardware audio lock sync encoding.

I think if a company put something like this together ... made sure it was both NTSC and PAL capable ... macrovision free ... well ... they would be making a HELL of a lot of money.

And I would be one HELL of a happy video capturing nut

So does anyone else agree with me? Is this even possible? If so is there a company or companies we can contact to get them interested in this?

- John "FulciLives" Coleman

P.S.
This should be either a PCI card and/or an external FIREWIRE device. We all know that every USB 2.0 external capturing device has been pretty much GARBAGE.

[The village idiot]

I can't say I really read your whole post, but I wanted to put some info in while it was in my head. There are devices that lock the audio to the video, but most of the hardware manufacturers don't allow it for one reason or another. For example we will look at 2 Razzle products. The DVC2 and DV Bridge both use a Philips saa7114 chip to take the analog video/audio and convert it to uncompressed digital. With in that chip, there is an option to lock the audio to the video, with the DVC2 you can change a registry setting to do this, the DV Bridge doesn't allow access to the chip, it uses an onboard micro controller to make all the settings.

I think that normally things go out of wack when the card does some other processing to the stream. That might be why the hardware encoders work fine, because they get the stream before it gets perturbed.

Refer to :
http://www.semiconductors.philips.com/pip/SAA7115HL_V1.html

The SAA7115 can capture the serially coded data in the vertical blanking interval (VBI-data) of several broadcast standards. It also incorporates also a frame locked audio clock generation. This ensures that there is always the same number of audio samples associated with a frame or set of fields. This prevents the loss of synchronisation between video and audio, during capture or playback. Furthermore the second analog onboard PLL optionally can be used to enhance this audio clock to a low jitter frame locked audio clock. All the functions of the SAA7115 can be controlled via I²C-bus.

The saa7115 is the replacement for the saa7114.

[The village idiot]

I finished reading and have more:

The saa7115 is signal standards agnostic, it simply doesn't care about NTSC or PAL, it will do both:

It combines a two channel analog pre-processing circuit and a high performance scaler. The pre-processing circuit includes source selection, an anti-aliasing filter and an analog to digital converter, an automatic clamp and gain control, two clock generation circuits and a digital multi-standard decoder containing two-dimensional chrominance/luminance separation using an improved adaptive comb filter. The high performance scaler features variable horizontal and vertical up and down scaling and a Brightness Contrast Saturation (BCS) control circuit. Based on the principle of line-locked clock decoding, the decoder is able to decode PAL, SECAM and NTSC signals into ITU-601 compatible colour component values.

So now the big question is this: Why don't more manufacturers take advantage of this feature? Well because it can cause some problems, but I'm afraid I don't remember what they are, look around the info for this chip, and I think you might find it.

[marvel2020]

Audio Sync whats that ?????.

Never had it, even when i was using a Pinnacle PCTV RAVE PCI card.

[jdjbuffalo]

I have the Canopus AVDC-100 and it works great.

I typically capture between 7 and 21 hours a week with it and never have a problem. I then take the DV and encode it to DivX (mostly) and sometimes to MPEG2 (DVDs). It works great and I would say the quality is at least 95% as good as the original (in any case) but probably more like 99% (in almost all caes).

However, from my experiences over the last 9 months that I've had it; I would have to say that I'm happy with ALL of the capturing its done. Even for the DVD quality shows/movies.

And I've had ZERO (yes, I said zero) problems with Audio and Video sync. I ALWAYS get perfectly synced shows/movies.

Buffalo.

[holistic]

Hmmmmm ..........looks like someones missed the bus. Discussion is on PCI/AGP video card sync issues. We are all well aware of the AVDc-100's abilities thank you.

Just a thought here for FulciLives.

Sync issues may be due to the timing on the system bus.

I never had any when i was using my AVeR PCI media card but i do remember dropping 1 frame every 10,000 (or so) with VDub and huffyuv. That may have been to adjust sync. !!.

][

[FulciLives]

I have the Canopus AVDC-100 and it works great.

I typically capture between 7 and 21 hours a week with it and never have a problem. I then take the DV and encode it to DivX (mostly) and sometimes to MPEG2 (DVDs). It works great and I would say the quality is at least 95% as good as the original (in any case) but probably more like 99% (in almost all caes).

However, from my experiences over the last 9 months that I've had it; I would have to say that I'm happy with ALL of the capturing its done. Even for the DVD quality shows/movies.

And I've had ZERO (yes, I said zero) problems with Audio and Video sync. I ALWAYS get perfectly synced shows/movies.

Buffalo.

If you think your Canopus ADVC-100 is so great then I might be bursting your bubble if you take a look at the following website:

http://www.geocities.com/fredthompson6/

Take a look at the LINK entitled "FlyVideo3000 vs. NTSC capture comparison Screen Grab"

Here is the image you will be seeing (this is a smaller slightly more compressed version)



On the LEFT you have a capture from a PCI TV tuner type capture card using a lossy codec (it doesn't say but I'm assuming HuffyUV) and on the RIGHT you have a capture that was done with the DV codec.

BIG DIFFERENCE if you ask me.

- John "FulciLives" coleman

[FulciLives]

Just a thought here for FulciLives.

Sync issues may be due to the timing on the system bus.

I never had any when i was using my AVeR PCI media card but i do remember dropping 1 frame every 10,000 (or so) with VDub and huffyuv. That may have been to adjust sync. !!.

][

I'm using an AverTV Stereo PCI TV tuner type capture card. This uses WDM drivers so I'm using VirtualVCR and I am using the dynamic audio resampling method of A/V sync.

Most of the time it isn't a problem. But sometimes it isn't perfect. There seems to be no reason that I can see why sometimes it is fine and othertimes it is off.

I should point out that I rarely if ever have dropped frames. But sometimes (even with 0 dropped frames) I still have A/V sync issues.

- John "FulciLives" Coleman

[overloaded_ide]

There might be more to this than the CARD.

I capture to Mpeg2 almost all the time, sometimes Mpeg1.
I never drop frames or get out of sync audio. (Maybe once on a very bad tape)

Does the fact I capture directly to mpeg prevent the sync problems you others have? Is it likely I would have the same sync problem if I captured to Huvy or other Avi?

Or am I just lucky?

I'm using a ATI AIW 7500 radeon, agp card for capturing.
I use the internal wire connection to feed the sound into the onboard sound connection for the cd audio.

I don't do the plug the wire in on the back thingy for sound on the line in.

[FulciLives]

There might be more to this than the CARD.

I capture to Mpeg2 almost all the time, sometimes Mpeg1.
I never drop frames or get out of sync audio. (Maybe once on a very bad tape)

Does the fact I capture directly to mpeg prevent the sync problems you others have? Is it likely I would have the same sync problem if I captured to Huvy or other Avi?

Or am I just lucky?

I'm using a ATI AIW 7500 radeon, agp card for capturing.
I use the internal wire connection to feed the sound into the onboard sound connection for the cd audio.

I don't do the plug the wire in on the back thingy for sound on the line in.

I'm not sure what the answer is to your question is but I originally wanted this thread to be more of a THINK TANK kind of thread about a product that seems as though it could be made but doesn't exist.

In other words I didn't mean for this THREAD to be about how to solve audio sync issues with existing hardware/software.

- John "FulciLives" Coleman

[Gazorgan]

Lucky?

I don't have sync issues on my cheapo card. I use IUVCR and sync the audio to the video. Huffy and Mjpeg, no dropped frames.

I think sync is a conglomoration of OS, Drivers, Hardware, and capturing software (well duh). Some people have a terrible time of it and if the truth be known, it's something they are doing. Like say using a certain virus scanner, or a particular chipset.

[trhouse]

I would agree that such a product would be very desirable. After looking into this a bit, it seems that there are only a few suppliers of chips that are used in most of the capture devices out there and that there is a lot of private labeling of products made by few actual manufacturers. For example, Emuzed seems to make capture products sold under the Dazzle, Pinnacle, and Adaptec names. Either that or they share the same product designer.

The manufacturers do not appear to have much to do with determining the performance of their product if the performance is really set by the chip manufacturer. Broadcom makes chips like the BCM7040 which say they have features to maintain sync yet I own one of those products and sometimes there is a sync issue, but whether the problem lies with the chip is not certain. I have captured the same video sometimes three time and two times there is a sync issue but on the third try it is perfect.

[NightWing]

Years ago this was a major problem.

One good example is when you have a video card and use the audio in of your computer for recording the sound. You are using two difference clock that are not in sync. Even though they can be derived off of xtals they are not in sync.

The old DC30 card has basically the same video section of a DC10+ card but had it own insync audio section. It uses the SAA as its front end a/d chipset. It would stay in sync.

The DC10 would driff out of sync in about 1 to 15 munutes with 5 being the norm. AVI_IO and later version of Studio correct this drift in software.

The best solution is to have the whole chain driven off of a temp controled master clock firing the sampling gates on both the A/D of the video and audio. Else left with software that is better done at time of recording.