Media Composer 3.1 Minimum PC Reqs

[Douglas R. Bruce]

Capturing HDV through the firewire and working with it inside MC as HDV media is not a problem.
It is when you try and export from MC as a Quicktime Reference file that you meet a problem.
You are warned that "Long GOP cannot be exported".
However it is easy to transcode by using a "Video mixdown" at that stage.

I f anyone is interedted in the Long GOP problem and solution you can watch one of my tutorilas in this thread:

70+ Tutorials on Basic MC tips - Updated January 30th - Avid Community

It is "Link07" in the list of over 70 MC Tutorials.

I prefer working with the native HDV inside MC and transcoding only the final timelines I want to export as QT-reference files..
Others prefer to transcode as early in the workflow as possible.
Regards,
Douglas

[David Parks]

Originally Posted by Bob Willis

. When you capture/digitize into AXP or MC without DX hardware it is captured as native format. HDV, XDCAM HD whatever, all have to be transcoded to DNXHD. All effects, transitions will be rendered to DNXHD.

Okay here is a test. First permit me for the purpose of discussion to define HDV as an m2t file.

That is the file format that is laid to tape or SD card. It is the file format if you use CapDVHS DVHSCap or another m2t capture utlility. It is the format that if you export HDV out of any other editor it would be m2t. It is the file format that is created when you export to HDV out of Avid.

So here's the test: take a non-tape m2t and import into an HDV project and look at what codec option is presented before import. DNXHD 145TR not HDV. I think the confusion lies in that the capture tool lists the format as HDV MXF. But, raw HDV is in fact like I said m2t.

All of this is under the hood stuff. In fact, when you go to export out to HDV Device it has to rebuild the transport stream and create a m2t file as a new stream. Remember that the file format that Avid edits in is MXF not m2t. Avid Liquid edits m2t.

The INTERSTING THING is that by accident I figured out how to one can import into another DNXHD without Mojo DX and unfortunately it only works with version 3.0 or higher.

Version 3 gives you the raster option on the format tab to choose between HDV, Standard HD, DVCPro HD, and XDCAM HD.

Capture HDV using 3rd party capture as m2t. Select format tab as Standard HD vs. HDV raster. Then DNXHD 145, 220, 220x, etc. shows up in your options. Even 1 to 1 MXF shows up.

I'm sure if does indeed work that there is some transcode and I bet the import will be slow.

I'll do some tests over the weekend.

I hope I'm not being too argumentative and let me know if I'm wrong. But I'm pretty sure that Avid doesn't edit raw m2t.

Thanks.

EDIT: I think everyone also needs to know that I'm referring to DNXHD TR, which is LONG GOP as a different stream as pure HDV. And it isn't the same as DNXHD 145. And yes QT reference doesn't work with Long GOP.

[David Parks]

Originally Posted by Douglas R. Bruce

However it is easy to transcode by using a "Video mixdown" at that stage.

Douglas,

I'm curious why you would use Video mixdown before you transcode your sequence.
Just wondering.

Cheers.

[Bob Willis]

Exactly my point Douglas. You can not export native HDV or native XDCAM HD material as it is captured in Avid, as a QT Reference file. You must transcode the material to an appropriate DNXHD form to be able to export as QT reference.

I too usually work with native hd until I have a rough cut finished and then transcode to DNXHD so that I can use QT reference to create whatever file I need in Sorenson Squeeze.

By the way Douglas, thanks for the many tutorials.

[Bob Willis]

Long gone are the days of simply digitizing DV material, editing and then outputing to tape and/or DVD. Even Beta SP has seen its last days. It is a long slog through all the various video formats, codecs and file formats to many different distribution paths. All this can be very confusing and sometimes the manufacturers of editing software do not make it very clear about their own products.

Here is the little I know about editing HD with Avid XPro and MC.

HDV and XDCAM HD are native MPEG-2 Long-GOP video in a MXF wrapper. Whether you capture from tape or disc or import files the video that is acquired by Avid is native MPEG-2 video in an MXF format. m2t is a HDV transport stream that can be imported and exported from Avid, but can not be edited. The m2t transport stream is converted to MPEG-2 video in a MXF wrapper.

You CAN NOT capture or import directly to DNxHD (in any resolution) in Avid without an Adrenaline, Mojo DX or Nitris DX hardware box. You must transcode the native MPEG-2 footage to the appropriate DNxHD resolution. It does not matter what version of Media Composer (or AXP) that you are using. I am currently using MC 3.1.2, the latest version.

David, I believe what you are seeing when you are importing HDV files is the same options that I have seen importing XDCAM HD files. Avid shows you the codec option for the appropriate DNxHD resolution before you import the file (such as DNxHD TR-145). This is for reference only. If you check in the Avid bin that you import the file to, you will find under the video heading that it is listed as HDV 1080i60 (or whatever form you shot).

A simple test is to highlight that clip and try to export the clip as a QT reference file. You will find that you get an error message that states that Avid can not export a Long-GOP file and that it must be transcoded to DNxHD to export.

Unfortunately, there is a reason that Avid can price that DX hardware where it is at present. It saves editing houses that can afford the hardware, time.

Ed, hope the addition of Avid MC goes well.

[Douglas R. Bruce]

Originally Posted by David Parks

Douglas,

I'm curious why you would use Video mixdown before you transcode your sequence.
Just wondering.

Cheers.

My train of thought is that it takes time to transcode the material.
When I capture material for a project I always capture more than I will actually use.

By transcoding only the finished project before exporting my QT-reference file, I am transcoding the minimum amount of footage.

It wouldn't be the first time that my train of thought was wrong......... but for the moment I find that this way suits me best.

Regards,
Douglas

[Vito DeFilippo]

Your reasoning is sound, Douglas, as long as you are having no performance issues while editing.

Transcoding before you edit will give you much better performance (more responsive playback, more layers in realtime, etc) than cutting native HDV.

But if your computer can handle it, your approach saves time at the start, and a fair amount of disk space.

[David Parks]

Originally Posted by Bob Willis

You CAN NOT capture or import directly to DNxHD (in any resolution) in Avid without an Adrenaline, Mojo DX or Nitris DX hardware box. You must transcode the native MPEG-2 footage to the appropriate DNxHD resolution. It does not matter what version of Media Composer (or AXP) that you are using. I am currently using MC 3.1.2, the latest version.

I have to respectfully disagree. From what I can tell, you view only the Intraframe resolutions as true "DNXHD" why I view also the "TR" resolutions that are Interframe (LONG GOP) as part of the DNXHD spec. Like I said, it is semantics. I don't want anyone thinking that they 100% have to transcode HDV. They can import m2t's into DNXHD TR and edit then transcode when they're ready for downconvert or need to convert to DVCProHD, XDCAM, or whatever the output. I do this all of the time because I archive my raw HDV on DVD as m2t and come in DNXHD 145TR. Call what you want, but it is not the just your same HDV stream that you record in your camera. It is a "rebuilt" stream on your timeline.

Also, QT reference does not work with any Interframe codec on export. How are the pointer files going to link to 15 frame GOP's vs. individual frames. This is a QT issue, it has nothing to do with DNXHD. QT reference only works with a Intraframe files. So, I don't see that as any proof.

After my test I do agree with you that no matter your setting, you cannot import m2t into a intraframe DNXHD without transcoding after import. I always knew it have to transcode. I thought that maybe it would do that on import, but it didn't.

Douglas. Thanks for tutorials. You confused me when you said you did a "video mixdown" (which is an operation under Special in the drop down.) So, I take it you meant transcode.
A video mixdown would force a additional compression hit.

That's all.

[Douglas R. Bruce]

Originally Posted by David Parks

........ Douglas. Thanks for tutorials. You confused me when you said you did a "video mixdown" (which is an operation under Special in the drop down.) So, I take it you meant transcode.
A video mixdown would force a additional compression hit.
That's all.

Thanks for that bit of information, David.
I didn't know that. (Yes, I am doing "Video Mixdowns" from the "Special" menu.

I'll have to reconsider that move!

Regards,
Douglas

[Vito DeFilippo]

Originally Posted by David Parks

A video mixdown would force a additional compression hit.

Not sure about that. A mixdown will render all effects and transcode native HDV to DNxHD. Then he outputs a QT ref for encoding.

Transcoding the sequence reformats all clips to DNxHD. Is it then already rendered? I don't usually use that workflow, so I'm not sure.

Anyway, both methods involve only one compression pass. Or am I missing something here?

Thanks, David...