Transcoding and rewrapping at DVinfo.net

Marty Jenoff · January 22nd, 2011, 03:56 AM

I'm a little confused - whats the difference between transcoding and rewrapping?

Do both keep the original timecode? What are the pros and cons to each?

Colin McFadden · January 22nd, 2011, 09:21 AM

We've got a blog post coming in a day or two at divergentmedia.com that goes in depth on this very subject, but in brief:

When rewrapping, ClipWrap leaves the video samples (the core video data) from the source untouched. It just rewrites the wrapper data, which tells QuickTime where to find each frame of data, what format it's in, etc. This means the rewrapping process is very quick (nearly as quick as copying a file).

For HDV content (M2T), this is fine, since Final Cut and other apps are well optimized for HDV-in-MOV. For AVCHD content, it's a bit trickier - because AVCHD is so much more CPU intensive to decode, apps like FCP don't deal well with it in its raw (rewrapped) format. It's fine for playback, but for serious editing the rewraps are a bit too demanding.

For those cases, there's transcoding. With transcoding, we decompress the video samples to raw, uncompressed video, and then recompress them using your selected format (Apple Intermediate, ProRes, etc). The workflow we generally recommend for FCP, FCE, iMovie, etc with AVCHD content is to transcode to Apple Intermediate, as it's a good balance between file size, performance, and quality (no quality loss from your original). Transcodes do take longer than rewraps though, since there's a lot more computation involved.

Hope that helps - otherwise, check the divergentmedia.com blog tomorrow or monday for a full, very nerdy writeup.

-Colin

Colin McFadden · January 22nd, 2011, 09:22 AM

Oh, also - all the settings in ClipWrap will retain Timecode, if your camera put it in the bitstream originally (not all cameras write timecode, particularly "consumer models")

Marty Jenoff · January 23rd, 2011, 06:25 AM

Thanks for the info. I'll check the site tomorrow.

So transcoding to ProRes does keep the timecode?

Colin McFadden · January 23rd, 2011, 08:10 AM

Yes, as long as your camera actually recorded TC (nx5u, hmc150, etc)

Marty Jenoff · January 23rd, 2011, 06:12 PM

Right now I have the JVC GYHD200 and the Firestore MRHD100. Planning on getting the Sony NX 5 soon.

January 22nd, 2011, 03:56 AM	#1
Marty Jenoff Regular Crew Join Date: Jan 2009 Location: Baltimore, MD Posts: 102	Transcoding and rewrapping I'm a little confused - whats the difference between transcoding and rewrapping? Do both keep the original timecode? What are the pros and cons to each? __________________ Marty Jenoff www.focalpp.com

January 22nd, 2011, 09:21 AM	#2
Colin McFadden Sponsor: divergent media Join Date: Jun 2004 Location: St. Paul, MN Posts: 201	We've got a blog post coming in a day or two at divergentmedia.com that goes in depth on this very subject, but in brief: When rewrapping, ClipWrap leaves the video samples (the core video data) from the source untouched. It just rewrites the wrapper data, which tells QuickTime where to find each frame of data, what format it's in, etc. This means the rewrapping process is very quick (nearly as quick as copying a file). For HDV content (M2T), this is fine, since Final Cut and other apps are well optimized for HDV-in-MOV. For AVCHD content, it's a bit trickier - because AVCHD is so much more CPU intensive to decode, apps like FCP don't deal well with it in its raw (rewrapped) format. It's fine for playback, but for serious editing the rewraps are a bit too demanding. For those cases, there's transcoding. With transcoding, we decompress the video samples to raw, uncompressed video, and then recompress them using your selected format (Apple Intermediate, ProRes, etc). The workflow we generally recommend for FCP, FCE, iMovie, etc with AVCHD content is to transcode to Apple Intermediate, as it's a good balance between file size, performance, and quality (no quality loss from your original). Transcodes do take longer than rewraps though, since there's a lot more computation involved. Hope that helps - otherwise, check the divergentmedia.com blog tomorrow or monday for a full, very nerdy writeup. -Colin __________________ Divergent Media Support www.divergentmedia.com

January 22nd, 2011, 09:22 AM	#3
Colin McFadden Sponsor: divergent media Join Date: Jun 2004 Location: St. Paul, MN Posts: 201	Oh, also - all the settings in ClipWrap will retain Timecode, if your camera put it in the bitstream originally (not all cameras write timecode, particularly "consumer models") __________________ Divergent Media Support www.divergentmedia.com

January 23rd, 2011, 06:25 AM	#4
Marty Jenoff Regular Crew Join Date: Jan 2009 Location: Baltimore, MD Posts: 102	that helps Thanks for the info. I'll check the site tomorrow. So transcoding to ProRes does keep the timecode? __________________ Marty Jenoff www.focalpp.com

January 23rd, 2011, 06:12 PM	#6
Marty Jenoff Regular Crew Join Date: Jan 2009 Location: Baltimore, MD Posts: 102	Right now I have the JVC GYHD200 and the Firestore MRHD100. Planning on getting the Sony NX 5 soon. __________________ Marty Jenoff www.focalpp.com

January 23rd, 2011, 08:10 AM	#5
Colin McFadden Sponsor: divergent media Join Date: Jun 2004 Location: St. Paul, MN Posts: 201	Yes, as long as your camera actually recorded TC (nx5u, hmc150, etc)