Funky Playback Problems with XDR in .MPG Format !
 

Hi Mike, Tommy & Fellow XDR Users:
I've never actually tested the .MPG DVD shooting feature of the latest official release firmware in the XDR, so I decided to go out and give it a whirl this morning. I am less than impressed with the results ! Using an almost new and entirely unused Sandisk Extreme III 8 GB CF card, I shot a 20 minute interview at the 35 Mbps .MPG data rate, which isn't what I would consider a very high data rate for the card I'm using folks. Here's what happens................

Results for playback of .MPG shot at 1080 i 59.94 MHz: Perfect picture and perfect sound in perfect synchronization across the entire file size.

Results for playback of .MPG shot at 23.98 p (Canon 24 F) with 3:2 pull down removal added to effect correct fps for resulting video file: About 12 minutes into playback the sound simply disappears and perfect video keeps on rolling. Stopping playback and attempting to resume it yields loud pops, clicks and horrible loud screeching noises !

This kind of reminds me of what I get if I try to playback a .MXF I-Frame recording with a data rate set too high for the capabilities of the particular approved CF card I'm using. This is the only other time I have ever experienced a failed playback of the video and audio signal out of the HD-SDI output of the unit itself.

EDIT: Turning the unit off and on doesn't return the unit to proper playback until about the 3rd or 4th time, but later in playback goes honky again with disappearing audio !

*Upon analysing the resulting .MPG files individually on my PC, I am happy to report that all the audio and video data is there. However, I want it to work out of my XDR as well.

** Why does the higher fps rate playback work fine and the lower data rate fps (23.98) not work ?? Shouldn't it be the other way around ??

***I'm putting the shout out to ALL XDR users to please test their .MPG 35 Mbps format settings and whip off some test recordings of reasonable lengths, say 20 minutes or longer and watch the playback from out of your XDR into a real HD-SDI capable monitor (I'm using the famed Sony LMD-940W HD Portable Studio Monitor).

What's with this funky-intermittent-unpredictable playback ?

Hi Mark. Interesting problem you have here. I'm experiencing the same exact problem but I' actually trying to proof out the exact cause and do some more research on when and why this happens.

I can tell you what I can say for sure. There is definitely a problem with MPG playback on the XDR. I've been able to see the MPG playback fail after anywhere from 40 minutes to in hour during playback of a capture. It fails reliably at any frame rate for me.

I'd be curious if nano owners experience the same thing during playback, or really if anyone cares since we probably don't use these devices for playback much at all.

I'll post more when I know more. For now I'm hoping they fix this known problem ASAP.

Thanks for the Feedback
 

Hi Aaron:
OK. So you also are experiencing some funky .MPG playback on your XDR, only, it seems to be taking longer on your unit before the point of actual playback failure is reached. Is this correct ? You also claim yours is happening at all frame rates ! I will go back and shoot some much longer takes - say 40 plus minutes and see what happens at 1080 59.94i. Also, why does my 59.94i 1080 .MPG play out from my XDR OK so far, but the slower fps rate 23.98 (Canon 24 F ) does not ? This is another head scratcher for me. I will go back and test some more.

EDIT: I re-read your post. You claim this is a *known* issue ??

Dear Mark and Aaron,

Yes, Aaron reported this issue to us.

We are working on it.

This seems to only involve playback of MPG files, as I understand it.

Aaron reported that this seems to happen when we switch from one card to another.

I'm Only Recording on One Card
 

Hi Dan:
I don't know if this is significant, but I'm only recording on one card for my testing and receiving this playback malfunction.

Sorry Mark, when I said it was a KNOWN problem, I meant known to me. I think we're all trying to clarify the problem so we know exactly when it is likely to happen.

Yes, I did notice the playback problem further into the playback. Usually 40 minutes or longer into the playback I would see the problem.

When I said it's happening at all frame rates, I should have said "all frame rates that I've tested". The problem does not appear to be tied to any specific frame rate.

Good Clarification Aaron
 

Hi Aaron:
OK. Thanks for this clarification.

Dear Friends,

Our Chief Engineer has been working on this problem since it was reported to us by Aaron.

He now has it fixed.

The problem was in playback of the MPG files. We were, when advancing from one file to the next, not completely finishing the audio in the Long-GOP structure before we advanced to the next file.

This correction will be in our Public Beta, which we will release as soon as possible.

Our Chief Engineer has 8-Channel audio working also, so this, any many other features will be included in this Public Beta.

8-Channel Audio will be supported in HD, in Quicktime and MXF only.

8-Channel Audio will not be support in SD, nor in MPG, nor in our ASI feature.

At this moment in time, we have not added the "Plus 2" audio feature; this is where we add the two channels of analog audio to the embedded audio. This will come, but I do not know if it will be in this Public Beta or not.

We have a few things to add, and a few things to fix, then a lot of testing to do before we release this Public Beta.

A Salient Question I Ponder
 

Hi Dan:
OK. I understand the difficulty with the XDR not finishing Long GOP before starting to open a new file on a *New CF Card*, however, my playback problems are all contained while recording and playing back files in *One* CF card only. Will the Long GOP completion fix also repair my playback malfunction on one CF card recording and playback session ? Please advise and thanks go out to the folks at CD who are working to write update patches and fixes for the Flash XDR :-)

* I understood even while setting file size to use 100% of the recording space on a CF card, this will still cause the XDR to close off a file @ 3.5 GB. If this is so, then it is conceivable to still see the .MPG playback fail while recording and playing back on a single 8 GB CF card, because the Long GOP of the first 3.5 GB file isn't closed properly at the end before going to open the next .MPG file with it's Long GOP.

Among the Fixes
 

...Hi Dan:
Will the fixes also include the repair of the Canon 24 F Jam-Sync feature (23.98 with 3:2 removal) ?

Thanks

Mark, I think Dan misstated the problem. It's not when advancing to the next card, it occurs when advancing to the next FILE. That is what I reported to them. This is where I saw the playback problems occur.

To the CD team, thank you very much for addressing this issue so quickly. I'm impressed that you were able to fix it so quickly.

Clarification
 

Hi Aaron:
Ok. Understood. It is when advancing to the next *FILE* and **NOT the next CARD** where the problem resides. Yeah, I'm glad they can come up with a fix so soon too.

Dear Aaron,

Yes, I misunderstood the problem. It is "File" not "Card".

In any case, we have fixed it.

Dear Mark,

Yes, we have fixed your issue also, Jam Sync in 24F, as I understand it.

. MPG & 24 F (Canon) Jam Sync Fixed Yay !
 

Hi Dan:
Wow ! Way to go CD ! Two major fixes ! (No sarcasm intended) Excellent and thank you ! :-) :-) :-)

Respectfully