XAVC what is it good for?

royfphoto wrote on 4/14/2014, 8:19 AM

I am very happy that the XAVC format will be able to smart render, for a while I couldn't detect the difference between it and Sony EXCAM HD MXF (1080 30p flavor) but having twice the bit rate & 10bit 4.2.2 it appears to be a very good (moderate) intermediate. It opens in (10.1.4LITE) Resolve, not Lightworks, plays well in VLC, imports into Premiere, not Speedgrade, not Sony ExCAM viewer, ok with Win Media Viewer (Win 8.1)
For those that know...what is the best method to "round trip it" into Resolve and back again?
I am hoping my client (PBS) will accept it as a delivery format as they did the Sony ExcamHD .mfx.

Comments

videoITguy wrote on 4/14/2014, 10:00 AM

I don't see in the cards where XAVC is actually intended as a digital intermediate. However the fact that Sony wants to brand this codec and use it as a direct camera stream and then keep smart rendering intact - makes its look like a special Sony solution.

A solution to what? Get camera footage out quick to a basic edit for upload ( ENG work?)

If you did not see this, please read - then review Sony's emphasis on branding this workflow....

Subject: RE: Pro 13 introduction from NAB
Reply by: NormanPCN
Date: 4/10/2014 7:15:47 AM

c. xavc (along with smart rendering) is appealing as both inter and archive, (would someone kindly explain the difference between xavc and xavc-s as intermediaries)

The XAVC spec supports Intra (I frames only) and LongGOP (I/P/B) encoding and uses MXF files. 8 to 12-bit, 4:2:0 to 4:4:4. Audio is always PCM.

Vegas has only implemented XAVC Intra 10-bit 4:2:2 at this time(VegasPro12).

XAVC-S is in a MP4 file and always uses LongGOP encoding. 8-bit and 4:2:0 chroma subsample. Audio is PCM.

XAVC Intra is the one with Smart rendering support in VP13.
XAVC-S bitrates are fairly high and give excellent quality. Around 50Mbps for 1080p30 with my GoPro mountain bike footage.

XAVC-S is marketed as the consumer format verses XAVC as the Pro market.

www.xavc-info.org/xavc/share/data/XAVC_SpecificationOverview_Rev2_130913.pdf

Message last edited on 4/10/2014 8:23:59 AM, by NormanPCN.

Subject: RE: Pro 13 introduction from NAB
Reply by: videoITguy
Date: 4/10/2014 7:58:05 AM

XAVC-S is intended for most efficient camera capture. Sony is the only camera maker directly offering it. Note the WHY these formats are being created is an attempt to overcome some of the limits of recording to memory card media.

Message last edited on 4/10/2014 8:03:40 AM, by videoITguy.

royfphoto wrote on 4/14/2014, 11:04 AM

I see a lot of advantages to it for me.. The implementation (in Vegas) of DNxHD is a QT container, although other NLE's have adopted the MXF version, QT does not work as quickly as MFX with my particular set up. Cineform doesn't work well in Win 8 (cannot transcode Canon MFX and DSLR files acknowledged by them). Uncompressed is not a option for the amount of data I sling around, and I want a file that plays nice with Resolve and my broadcaster,
Possible drawbacks are that it is compressed at High 4.1 which sucks a lot of processing power

videoITguy wrote on 4/14/2014, 1:24 PM

and my friend ,...royfphoto, keep in mind it is very long GOP. which unlike cineform .avi or .mov is a digital intermediate down to frame by frame accuracy.
The emphasis on Sony for branding this into the ENG delivery chain is speed of turnaround from camera to edit, to upload at a most basic level. The same Sony cameras will offer >MXF container for Mpeg2 for a little better usage in other production workflows.

John_Cline wrote on 4/14/2014, 4:17 PM

XAVC is I-frame only like Cineform and DNxHD, XAVC-S is long GOP.

royfphoto wrote on 4/15/2014, 5:12 AM

Media info shows it to be I frame.

ushere wrote on 4/15/2014, 9:52 PM

so, in simple language, would i be better off using xavc as an intermediary rather than the hd.mxf i use at the moment*

*video footage is usually cc'd, and subjected to (when needed), noise reduction (neat), stab (mercalli), and occasionally mb looks.

videoITguy wrote on 4/15/2014, 10:06 PM

While it appears that this thread was ostensibly created to push XAVC as a great intermediary - I say not so fast.
What I am asking people such as yourself to consider - is to read the tea leaves, try to understand what Sony is doing and why.

SCS as a part of the Sony business (albeit very small) is thrusting some direction toward creating a fast turnaround workflow by including XAVC in the encoder category and XAVC-S as their branding it to the hardware (read camera over $6 grand). By asserting their branding they are trying (via the marketing) to set themselves apart from the other workflows like Apple Prores or Panasonic's AVC. XAVC works good in Vegas and it would be smooth as butter should you adopt this line of Sony.

OldSmoke wrote on 4/15/2014, 10:10 PM

And what is wrong with that?

ushere wrote on 4/15/2014, 10:12 PM

appreciate that vITg, and am aware that every other man out there wants me to adopt THEIR format and workflow. some things never change eh?

so what i gather you're saying is xavc would work better (smoother playback, etc?) than mxf in vegas?

i haven't had time to do any real research (has anyone?) with regards to xavc (i frame), but would like to hear real world experiences....

NormanPCN wrote on 4/15/2014, 11:04 PM

Sony always creates codec brands. It seems to be their thing. XDCAM is nothing more than mpeg-2 with specific parameters. HDCAM SR is mpeg-4 SStp.

Sony XAVC marketing is all about 4K. Of course they support HD as well to extend the XAVC brand there. mpeg-2 was just not going to be as good for 4K and computers do pretty well these days with AVC.

So Pro Sony cameras will support XAVC Intra for a little higher image quality capability and less expensive cams will be XAVC-S. XAVC-S was announced well after XAVC.

XAVC Intra makes a killer camera format. Panasonic has had its own AVC Intra flavor for a while and Vegas 12 supports it too.

I think XAVC Intra can make a nice Intermediate format. I-frames only is what you want for intermediate. The bitrate of XAVC is probably high enough for quality about as good as other inter codecs.

Any AVC decoder should be able to handle XAVC, but with the XAVC brand on a product at least it has been certified at some level. One nice thing about AVC is that it is ubiquitous. Everyone can handle AVC.

videoITguy wrote on 4/15/2014, 11:30 PM

Now only if VegasPro had 10 bit output...
and it had the capability to be monitored in preview as 10bit
and of course you want the high-end camera $6grand plus with
10bit recording possible...

The core technology of XAVC is h.264 mpeg-4 AVC, the same technology that is used in AVCHD cameras and DSLRs. But while AVCHD typically runs between 24 and 35mbps and is 8-bit 4:2:0 Long-GOP, XAVC aims much much higher. The reason XAVC was invented was Sony needed a next-generation format to be able to deliver 4K content with. It needed to be high quality in order to appeal to the commercial and cinema world. One important aspect was moving up to 10-bit recording. Sony’s also not a big fan of licensing existing codecs. So, in 2012 when they were getting ready to launch the F5 & F55 they wanted to have their own high quality deliverable native editable format that could encompass 4K workflow. Hence XAVC was born.

There are a few current flavors, or implementations, of XAVC. The first is full quality XAVC. This is a 1080p, 100mbps(at 30p, 200mbps at 60p), 4:2:2, 10-bit, Intra-Frame format. It’s extremely robust. It can also be 4K, 300mbps(at 30p, 600mbps at 60p), 4:2:2, 10-bit, Intra-Frame format.

There is another flavor that is very similar but it is Long-GOP. This is a 1080p, 50mbps(at 30p, 100mbps at 60p), 4:2:2, 10-bit, format. So you still retain much of the detail but you lose motion information. It can also be 4K, 150mbps(at 30p, 300mbps at 60p), 4:2:2, 10-bit. This flavor of XAVC hasn’t been put into use yet but it is expected to be made available as a firmware update to current XAVC hardware during 2014............

NormanPCN wrote on 4/15/2014, 11:33 PM

so what i gather you're saying is xavc would work better (smoother playback, etc?) than mxf in vegas?

If by, MXF in Vegas, you mean the mpeg-2 HD stuff then XAVC (also mxf) will not be as fast decoding as that. Nothing AVC will decode as easily as mpeg-2 even at the same bitrate. That does not mean it will not be smooth. If your machine is at its limits now, then I would say you will have a problem.

The XDCAM mpeg-2 stuff is 35/50Mbps and mpeg-2 for HD.
XAVC Intra for HD is a little over 100Mbps.

I absolutely would be using XAVC Intra for intermediates to Handbrake except Handbrake does not handle multi mon channel MXF audio. It cannot take two mono channels and treat them as stereo.

DNxHD sucks performance wise. I need Quicktime. Yuk. and QT in Vegas gets that stupid intermediate temp file which slows things down.

I have done some visual quality tests and XAVC is just like the source files.

I also tried 5(4?) generations of rendering and it held up well. This test I just did out of curiosity. I tested Cineform, XAVC Intra and HDCAM SR Lite, Sony AVC and Mainconcept AVC. Surprisingly HDCAM SR Lite did not fare so well. Sony AVC did not do so well. Sony/MC AVC I looked at as low control point to compare against. MC AVC at camera bitrate was nearly as good as the intermediates which surprised me a little.

Tests like this are easy. Find a 10 second clip of high quality fine detail. The short clip keeps the time of multiple renders down. Then put everything on separate tracks and solo each test against the original at various frames.

ushere wrote on 4/15/2014, 11:53 PM

wow norman, you certainly did your homework on it ;-)

many thanks - and yes, once i have a moment or two i'll run some tests myself, but your summation is a great starting point.

thanks