When exporting QT ref files. the option to use Avid DV CODEC appears.

Does that mean a true DV codec. Like 25mbs DV 4:1:1. If that is the case would sending out exports degrade the quality of footage if you export a section of video with a 1.1 TITLE.

would the tile and the footage be reprocessed with a dv25 codec?

Also why is the stadard 30i project in avid 720x486? whats the extra 6 pixels for. AE calls this D1.

what is d1 and why is it Avid standard for SD?

jason.adams:

When exporting QT ref files. the option to use Avid DV CODEC appears.

There is no codec involved when doing QTref exports it references the media.  If you captured all your files using DV25, then they are already at the Avid DV Codec.  If you captured using DNx145, then they will export as DNx145. 

jason.adams:

Also why is the stadard 30i project in avid 720x486? whats the extra 6 pixels for.

NTSC SD is 720x486... that's just the way it is.  DV resolutions are 720x480, so your question really should be "why does DV drop 6 lines?" as SD/D1 came first.

jason.adams:

what is d1 and why is it Avid standard for SD?

D1 is the name of a deck that Sony introduced in 1986 (see wikipedia.org)

It's not only the Avid standard for SD, it is THE standard for SD.  Again, SD DV is not true SD (in the absolute sense) and in many ways why lots of broadcasters still reject it.

Thank You so much for  explaining that. I appreciate it.

But I still don't get the little check box option of use avid dv codec. Are you saying that it is irrelevent for QT REF.

Also are you saying that if I use the Avid dv codec on a QT MOVIE (NOT REF) that it will be 720x486.

Thanks SO MUCH.

It would be irrelevant for QTref and DV is always 720x480.

Kenton.VanNatten:

It would be irrelevant for QTref...

Ahh, but doesn't the Avid DV checkbox need to be checked when working with DVCPROHD material, even in a Quicktime Ref?

I'm pretty sure that even with a Quicktime Ref file, the Avid DV box needs to be checked so that the QT Ref file sets the appropriate flag for playback of DVCPROHD material with the Avid DV100 codec?

I'll have to check this with some DVCPROHD material...

(Yup, just checked with some DVCPROHD material. QT Ref without the Avid DV box checked, blank screen, nothing. QT Ref with the Avid DV box checked, full playback.)

The Avid DV box doesn't mean "DV - 4:1:1". Its referring to the Avid QuickTime codec.

Which Avid DV codec is this? Aren't DNxHD, 1:1, ect. all QT codecs?

And doesn't QuickTime Reference just link to the source media, no codec involved?

I'd love a really clear explaination of what the "Use Avid DV Codec" check box actually does. Reading up on it and searching Help just have me more confused.

Thanks very much

I  never use the "Use Avid DV codec" because I always thought that it forces to export as DV... maybe that checkbox has a misleading description.

This is a can of worms you opened here....

When you tick Use Avid DV codec, you get:

1. From DV

The Avid DV codec is used by the program that plays the clip back.

If 601 was ticked, it is replayed with 601 levels.  If RGB, it is replayed with RGB levels.  This is done by the codec during the replay process.  The media itself is not re-processed.

In PAL, the clip is Field 1 first, even though DV is normally Field 2 first.

2. From DVCProHD

The Avid DV100 codec is used by the program that plays the clip back.

The clip is 601 or RGB levels according to the settings in the export.

3. From Meridian (eg 2:1)

The clip is always Avid Meridian compressed regardless of whether 'use Avid DV Codec' was selected or not.

If you don't tick Use Avid DV Codec:

1. From DV 

The Apple DV codec is used to replay the clip

The clip is replayed with RGB levels regardless of the export setting (601 or RGB) chosen

In PAL, the clip is Field 2 first.

2 From DVCProHD

The Panasonic DVCProHD codec is used to replay the clip

3 From Meridian compressed.

As above, the Meridian codec is used

If you export from a Sequence with mixed resolutions, the export may not work!  The QT ref references all the media in the sequence, and the programme that replays it will have to be able to use multiple QT codecs.  

I made a seq with an uncompressed title on a dv clip.  I rendered the title uncompressed, then exported as qt ref (with Avid DV Codec).  In QT player, the Movie Properties say it is Avid DV, but in the 'resources' tab it lists the uncompressed precompute as one of the media files it needs to play the movie.  So QT player can play a ref file with a mixture of resolutions.  

I then exported only the in/out section which had the title on it.  QT player then says the codec is Avid 1:1x.

In my opinion, it's safer to transcode all the media to the same resolution first.

Hope this all helps! 

Kenton.VanNatten:

It would be irrelevant for QTref and DV is always 720x480.

I've been doing tests on this lately (http://community.avid.com/forums/t/70011.aspx), and my tests show that the "Use Avid DV codec" option is definitely NOT irrelevant to QTRef output.  I notice two distinct differences between checking and not checking the "Use Avid DV codec" option when outputting QTRef files.  MikeyB already pointed out the first one, i.e:

If you don't tick Use Avid DV Codec:

1. From DV 

The Apple DV codec is used to replay the clip

The clip is replayed with RGB levels regardless of the export setting (601 or RGB) chosen

In PAL, the clip is Field 2 first.

The other difference is that ticking the "Use Avid DV codec" box causes the resulting QTRef to be 720 x 486 instead of 720 x 480 (which is what you get if you don't tick that box.) This now confuses me given that with the "Avid DV codec" box checked I get the incorrect resolution, but without it I get the RGB levels that MikeyB mentioned.  Are the luminance levels just an issue with playback in QT, or can this effect encodes?

Bottom line, which is the correct option to use when the target is an encode for DVD?   This was not an issue with Avid XPro since the "Use Avid DV codec" option resulted in 720 x 480 QTRefs.  It's only MC that is creating QTRefs with 486 lines.

Thanks,

Larry

I didn't know about the 480 vs 486 lines thing - I'm a PAL guy - but it makes sense.  What the Avid DV codec is doing is to make DV material 'look' the same as non-DV.  

It should make no difference to an encoding program - if it can handle Avid Meridian compressed QT with 601 levels, it should be able to handle Avid DV with 601 levels.  NTSC DVDs are 720x480, so 6 lines have to be 'lost' from non-DV video in the processing of the MPEG-2.  The same processing should just crop back off the black that the Avid DV codec adds top and bottom of frame.  

That said, it may depend on the settings within the program that's interpreting the file - for example, After Effects assumes all PAL DV is Field 2 first, and incorrectly flips the field ordering of Avid DV codec clips.  I suggest you do some tests to see what your DVD authoring s/w does.  

MikeyB:

I didn't know about the 480 vs 486 lines thing - I'm a PAL guy - but it makes sense.  What the Avid DV codec is doing is to make DV material 'look' the same as non-DV.  

It should make no difference to an encoding program - if it can handle Avid Meridian compressed QT with 601 levels, it should be able to handle Avid DV with 601 levels.  NTSC DVDs are 720x480, so 6 lines have to be 'lost' from non-DV video in the processing of the MPEG-2.  The same processing should just crop back off the black that the Avid DV codec adds top and bottom of frame.  

That said, it may depend on the settings within the program that's interpreting the file - for example, After Effects assumes all PAL DV is Field 2 first, and incorrectly flips the field ordering of Avid DV codec clips.  I suggest you do some tests to see what your DVD authoring s/w does.  

Maybe this is the reason that I always must test for f1 or f2 before I make a DVD? It is not a difficult behaivor of Avid, it is a pilot error there I sometimes check and sometimes not check.

As for the question about the six lossed lines in NTSC. DV, and I think also Mpeg2 and mpeg-4, use block of 8 pixels then they make the compression and 480 is evenly divieded with 8, 486 is not.

MikeyB:

NTSC DVDs are 720x480, so 6 lines have to be 'lost' from non-DV video in the processing of the MPEG-2.  The same processing should just crop back off the black that the Avid DV codec adds top and bottom of frame.

The question I still have, however, is exactly "how" the lines are added in Avid (since I'm dealing with 480 line source material), and exactly how they're eliminated in the encoder.  I would think Avid would simply "add" six lines of black, but it would be nice to confirm this, and to confirm exactly where the lines are added (i.e. is it 3 lines to both the top and bottom of the frame?)

On the other end, does the encoder simply crop off the lines, or does it scale the image?  If it crops, does it crop the same number from the top and bottom that Avid adds?  If so, everything is fine.  If it scales, however, there will be some artifacts that might not be readily apparent, but that will still be something worth avoiding.  I've tried to find out how CCE Basic (the encoder I'm using) deals with the extra six lines when creating elementary mpeg2 streams, but so far all I've found is other people asking the same question, and Cinema Craft has not yet gotten back to me on this.

Thanks for any further information on this,

Larry

It does seem that with some comparing of files you might be able to determine if they've been cropped, padded or scaled. I would think cropping and adding lines is what's done, but I don't know and my system is not available right now for me to test on my own.

Good luck ;).

Well, as I say, I'm a PAL guy but my understanding is that the codec pads the image out with 4 lines of black at the top and 2 at the bottom.  

As for your CCE encoder, what does it do with real 720x486 pixel NTSC?  And why would it do anything different with Avid DV?  I think you're probably worrying unnecessarily.