Lossless Viewing

[Dennis Hull]

I have trouble with lossless compression so once again excuse long note. How do I take high quality firewire output from DV camcorder, convert to analog with minimal quality loss, and view on TV at reasonable cost?? Without understanding it, I have been dancing around this question with many of my posts. Took a comment from Keith on NLE thread to trigger this, but I now understand the D/A converters on consumer level DV camcorders (Sony TRV 9 for me) are probably not great. So when I view DV tape using S-VHS output from camcorder to TV I could be losing a lot of the quality inherent in the DV tape due to poor D to A conversion of the TRV 9 chipsets.

Keith edits on NLE and outputs DV to DVD and then views DVD on TV thereby bypassing D/A converters on camcorder. But, this relies also on quality of D/A chipsets (and quality of DV to MPEG 2 conversion) somewhere in that process so do some hardware cards from Pinnacle, Canopus whomever have higher quality D/A chipsets and even higher quality DV to MPEG 2 conversion than others when outputting edited DV to DVD or their breakout boxes?? And, rather than buy DVD burner I have been thinking about buying a DVD stand alone recorder that has firewire input (like one from Phillips). I assume they convert firewire DV input to MPEG 2, burn onto DVD, and then use D/A converter chipsets to output using S VHS or component output. Is there a big difference in DV to MPEG 2 and D/A converter quality in these DVD recorders??

[Zac Stein]

Without spending a boatload of money, the absolute only way is to print your edited footage back to a dv tape via firewire. That represents the least amount of loss.

Other methods include, printing to sp beta or digi-beta which would yield good results, if you print to dvd in mpeg2 fashion you will at the mercy of how good your encoding is.



kermie

ps. remember the only time it goes analog (correct me if i am wrong) is when you play it off the tape. Goin down the firewire from the tape to the pc, or from the pc to the tape, it remains digital all the way.

[Josh Bass]

Could you print to a digital format and then have a transfer house put it on analog? I thought I remembered from when me and a buddy had a movie dubbed, it was like 8 bucks a copy to put it to VHS. I've noticed that when I output from my camera, via RCA cables to a VHS tape in a VCR (that's the only way I can do it at home) that the quality of the VHS is pretty low, definitely lower than, say, a tape you would rent at a video store. I'm guessing a transfer house can do it better. But I have no real idea.

[Andre De Clercq]

The highest image quality out of yr DV footage (which already has it's own limits) is optained by a direct conversion from DV into analog components (RGB or YUV) and input these signals into a TV, projector...DVI connection could under some conditions even be better for visualisation on pixel based displays, but this is I think, beyond this dicussion. The quality reduction when using composite (RCA) or Y/C is not so much the D/A conversion problem, but the color encoding step (PAL /NTSC) which is added for getting those standard outputs. Color encoding lowers bandwidths, generates color shifts, color leakge due to futher reduced chroma bandwidth, moire... and the image quality strongly depends on the performance of the display color decoder performance. Copying to VHS is of course a major quality reduction step and the existing Y/C or RCA outputs on camcorders are more than good enough as a source for this purpose. Pro copiers have proc amps not to correct the camcorder signals but to counteract as much as possible the (S)VHS degradation. For this reason, good tranfer houses can make better copies. Intermediate MPEG2 conversion is not bad, avoids the color encoding ( if the DVD is connected through RGB/YUV) but adds an extra MPEG2 compression/decompression ( extra motion artifacts)and is only advisable if a performant MPEG2 encoder is being used set on a low compression level.

[Jeff Donald]

The quality of the MPEG2 encoding has many variables. The best quality I have seen relies on seperate hardware processors (PCI board). They are also much faster than the software encoders. The Apple QuickTime MPEG2 encoder is a combination of speed and quality. Cleaner 5 and 6 (software encoders) are also available. Cleaner 6 is said to be much faster than 5. I use Cleaner 5 for my projects that require the best visual quality.

Jeff

[Andre De Clercq]

We used to be quite a bit involved in pro MPEG2 hardware encoders and decoders at Barconet (see http://www.saeurope.net/products_barconet/index.asp). Like Jeff mentions there are a lot of parameters involved, but transcoding from DV to MPEG2 ML needs still some extra steps, like DV decompression to (at least) DCT level, interpolation (DVD needs 4:2:0!) and some more tricks and trade offs. In general it turns out that most consumer MPEG2 encoders/transcoders (HW or SW) cannot equal the original DV stream even if only I frame GOPs are used and even when connecting through components (RGB/YUV) vs connecting the original DV through Y/C.

[Dennis Hull]

Thank you and I think you are right in all you say, but my concern was how to get video off the DV tape and onto the TV cathode ray tube with least amount of degradation from what is on DV tape in digital form. As you and dre mention, going from DV to MPEG 2 even though all digital could result in "loss" from original DV signal depending on how good the encoder is.

[Dennis Hull]

Thanks for input and I think dre also touched on why transfer houses can give better quality dubbing due to better equipment like proc amps??

[Dennis Hull]

Thanks for input on hardware processors for MPEG2 encoding-- do you have any name brand recommendations?? I am in PC Win 98SE environment.

[Dennis Hull]

I was in deep water before and your helpful comments are a rope to help pull me where I can get my feet on the ground. But, when you get time, can you confirm my understanding please. Apologies to all for length of this, but dre is getting me close to dry ground and I really appreciate this.

1. What equipment is available to do a "direct conversion from DV into analog components (YUV) and input those signals into TV"?? at prosumer level cost. That would be the best thing to do.

2. Not clear on your color encoding comments. Is that the general lumenance and chromenance issues relating to how VHS and S VHS handle mixing those together--- i.e. the difference between VHS composite output and S-VHS (Y/C) output?? And is that what your later comment about pro copiers using "proc amps" to counteract S-VHS degradation refers to?? --they use some kind of processors to do a better job seperating colors from the S-VHS signal??

Or, my inexperience REALLY showing here, strictly speaking is there a seperate digital to analog conversion done by my camcorders D/A converter and than a seperate color conversion step also done by camcorder output converter and that "color conversion" step is where the problem lies with what my camcorder outputs?? And this is different from the inherent color conversion problems with VHS or S-VHS??

OR, is the output from S-VHS jack on camcorder just fine and there is some problem--as you put it-- with "the display color decoder performance" on the TV -- again the issue of how the color seperation issue with S-VHS is processed when signal is recovered to be viewed on TV.

Bottom line, is there a quality problem with the chipsets or whatever consumer and prosumer camcorders use to convert DV digital tape data into viewable (on TV) analog output??

3. In your MPEG 2 comments, not sure what you mean by "avoids the color encoding." Is that referring to lower quality color encoding from S-VHS vs MPEG 2??

I have at least read about different compression methods and amounts between DV and MPEG 2 (intraframe and interframe, higher compression with MPEG 2) and lumenance chromenance (but I thought MPEG 2 was 4-2-2 vs 4-1-1 of DV).

I would use either an "onboard" DVD burner in computer so to keep signal digital at all times OR I wonder about using an external DVD recorder with firewire input to burn to DVD??

4. Could you explain the comment about "performant MPEG 2 encoder set on low compression level." Is that referring to using hardware MPEG 2 encoder rather than software and using least amount of compression you can use and still be in the MPEG 2 format??

5. I understand MPEG 2 does not equal DV "quality" due I guess to more "lossy" compression. However I am not sure from your last post if you are saying due to lossy compression of MPEG 2 I would be better off somehow using the S-VHS output from my camcorder (if I could figure out how to correct the color decoder thing) ???

Many thanks to all who have or will contribute to this. Just call me high bandwidth.

[Andre De Clercq]

Dennis, like I wrote., don't go through another conversion step. If you realy want "the best"(...and the most expensive!) buy a DV to component convertor (like DAC-2) or a pro DV VTR (like Sony DSR 15) and an RGB or YUV compatible TV (like many today) or a good projector and nobody will have a better DV image (if the footage is 100%). Also a projector (Marantz, ...) with direct DV 1394 input will give you the best possible from DV footage

[Jeff Donald]

Something like the Laird LTM-5500http://www.lairdtelemedia.com/produc...wire.html#5000 is near the tops for converting to component. There are more expensive convertors but you get into line doubling, tripling etc. The DAC-2 is a less expensive alternative. The LTM-5500 supports balanced audio, RS-422 serial control and in my opinion, slightly better picture quality (slightly better S/N ratio, to my eye). However it is probably 3 times the price.

Jeff

[Zac Stein]

Dennis,

Stop confusing yourself.

It is actually quite simple in regards to the reason certain connectors will yield better results.

Imagine a pipe, now the first pipe is the size of a straw(composite) and you are trying to put a cupcake through it. When it comes out it will be mangled. It will still resemble a cup cake and taste like a cup cake, but be mushed up and mixed together.

Now you have a bigger pipe, slightly smaller in diameter than an actual cupcake (s-video). The cupcake is slightly mangled but much harder to tell, and if you touch it up by fixing up the sides of it with your fingers (television colour adjustments, sharpness controls) to most people at a glance it seems almost perfect.

Now a pipe that is a little bigger than the cupcake (component) pops right through, nothing needs to be touched.

That is what these connectors are like, while composite shoves all video signals down one little wire, you get a lot of degradation. (vhs is native composite).

S-video however seperates the greylevels down its own line, and the colour down its own line, less problems, but still elements of the signal are being pushed together. This is also why s-video looks very shap, because the blacks/greys are prominent from their clean signal in contrast to the colours still being forced together.

Then you have component, it has its own channel for greyscale, and two more dedicated for colour. Less has been mushed together, and this method (native to dvd) also presents pretty much the native signal or dv, hence the least amount of down conversion to fit into a little pipe, so will yield the best results. (but is only around %5 better than s-video in percieved quality)

Rgb is 3 dedicated channels of red, green and blue and has to make up the grey scale from that pallete.


The quality of the DAC in your dv camcorder is quite irrelevant in the end, these days almost all of them are of equal quality, the only time you will see a marked improvement (read maybe a %5 improvment) is when you start spending absolute $1000's on equipment. The s-video from your camcorder is fairly decent and represents almost the best picture from your dv footage. This is the same rule of thumb for dvd players, they do the same proccess and the s-video derived from their signal is a DAC of a native component signal into an analouge picture with its colour imformation brought together and greyscale pushed down the s-video cable.

I hope this helps.

kermie

[Dennis Hull]

Makes sense, minimize conversions--S-VHS and either DAC-2, Laird or DSR-15 route. Just for comparisons, found Sony DSR-11 for $1999.00 at B&H (will continue looking for DSR-15); DAC-2 for around $650 and Laird website gives about $1800 (about 3 times as you said Jeff). Thanks again for guideance.

[Dennis Hull]

Thanks, Kermie, and let me digest your last note.