Hi.

Here's a problem showing the audio sync going out at the 4GB split point, more details in the YouTube video description.



Cheers,
dave.

Old news. Use mkvmerge and the audio will sync back up, same thing happens with the OP.

Wiz33 Posted at 5-22 07:28
Old news. Use mkvmerge and the audio will sync back up, same thing happens with the OP.

No it's not old news.

There is audio information missing during the split, so you'll never have a clean edit/join. This means that if you've important dialogue or audio during the point where the Action does its file split, it's ruined. Which is a serious problem for any acquisition that can't be re-taken.

As for re-syncing. Anyone who knows how to use an NLE can simply apply an offset there, which makes your suggestion redundant on a number of levels.

The missing audio is in the next file. Adobe for some reason can't join them back but mkvmerge can. Search the Osmo Pocket section and you'll see the same problem and solution.

Wiz33 Posted at 5-22 08:26
The missing audio is in the next file. Adobe for some reason can't join them back but mkvmerge can. Search the Osmo Pocket section and you'll see the same problem and solution.

No, the missing audio isn't in the next file, this is what I've shown in the video and described in the YT description.

For anyone else who doesn't quite understand what's going on. When the Action is doing it's file split, the second part does not contain continuous audio from the previous section. So, after re-syncing the second part, which you can within itself but with a gap in the audio at its start. It will be missing audio information that means that there will be a blank audio space in the join/cut and no continuous audio.

The audio is early not late. Which means you have to move it late to re-sync in the second part, therefore an audio gap.

I'll ask:  How does GoPro handle the split?

David_Harry Posted at 5-22 08:53
No, the missing audio isn't in the next file, this is what I've shown in the video and described in the YT description.

For anyone else who doesn't quite understand what's going on. When the Action is doing it's file split, the second part does not contain continuous audio from the previous section. So, after re-syncing the second part, which you can within itself but with a gap in the audio at its start. It will be missing audio information that means that there will be a blank audio space in the join/cut and no continuous audio.

Dave, is that possibly due to the issue of video latency?  

Oh-no Posted at 5-22 10:51
Dave, is that possibly due to the issue of video latency?

Hi.

It could be.

When any camera records video and audio there will always be a slight delay between both of them from within the camera. The picture will be processed to whatever degree as will the audio. But the video may be processed quite a bit, say EIS for instance, which takes longer to process. Once the video exits the camera's buffer/memory/frame store, whatever you want to call it, it is delayed from what hit the sensor, latency.

Processing will also happen with audio and then it's compressed too to it's output codec, in the case of the Action and Pocket it's AAC. Although the processing time of audio is a lot shorter as it's way more easier to deal with. This is usually done near real-time and a lot quicker than even one frame.

The final video has to be compressed and then interleaved with the audio into the final file container/wrapper. This process is usually called muxing. To get both the video and audio in sync for the final muxed file there has to be an offset applied. This is usually called latency or delay compensation.


The only reason why it may not be the Action's latency causing this issue is because it should be the same for both files but only effects the second one.

Regardless of whatever is causing it, there is a problem and examples like this will help DJI to know that something needs fixing.

BTW. HDR looks awesome on the Action, I'll have some examples up soon.

Cheers,
Dave.

David_Harry Posted at 5-22 08:53
No, the missing audio isn't in the next file, this is what I've shown in the video and described in the YT description.

For anyone else who doesn't quite understand what's going on. When the Action is doing it's file split, the second part does not contain continuous audio from the previous section. So, after re-syncing the second part, which you can within itself but with a gap in the audio at its start. It will be missing audio information that means that there will be a blank audio space in the join/cut and no continuous audio.

Ok this is still the same problem as with the OP except that the OP will cut off a fraction of a sec of audio before the video at the time of the split which appears in the first fraction of a sec on the new file but here, the OA cuts off the audio a fraction of a sec after the video. So basically, instead of a audio gap that would appear on the OP, the audio got ahead of the video. I don't know why it's reversed of the OP but Since the way it happens on the OP can be easily fixed. All they have to do is use the OP split method on the OA. Once again. What software are you using to join the files?  If it's not mkvmerge, you might want to give that a try. Yopu need software that will look at both the auido and video track when joining instead of just joining both based on the video.

David_Harry Posted at 5-22 11:33
Hi.

It could be.

Hi Dave.

I have noticed that when looking at the video information of any Pocket files I've recorded that the audio is always tagged at being 46.857FPS regardless of the video FPS selected.
I've been told on an editing forum that this is not unusual but could it have a bearing on the problem?
Also in real terms, how long a clip does this effect depending on the frame rate and resolution? So far I've never had a split file to look at.
I seldom record more than 5 minutes at a time. If I want longer it's normally a still shooting position and I would use my DSLR on a tripod.

Wiz33 Posted at 5-22 12:06
Ok this is still the same problem as with the OP except that the OP will cut off a fraction of a sec of audio before the video at the time of the split which appears in the first fraction of a sec on the new file but here, the OA cuts off the audio a fraction of a sec after the video. So basically, instead of a audio gap that would appear on the OP, the audio got ahead of the video. I don't know why it's reversed of the OP but Since the way it happens on the OP can be easily fixed. All they have to do is use the OP split method on the OA. Once again. What software are you using to join the files?  If it's not mkvmerge, you might want to give that a try. Yopu need software that will look at both the auido and video track when joining instead of just joining both based on the video.

I tried the software you suggested a couple of ways and the resulting files were the same as the originals. I've also tried in other de-mux/muxing software and de-muxed the elementary streams which gave the same results.

I used to master and program a lot with Scenarist and many other DVD/BD authoring applications so am very familiar with the process and used to re-formatting the timings of elementary streams into program and transport ones for various 'Book' standards. My NLE is Edius.

So with all that said. When someone is reporting a problem for the first time on a new piece of kit, maybe it's best not to lead with 'old news'.

Ray-CubeAce Posted at 5-22 12:44
Hi Dave.

I have noticed that when looking at the video information of any Pocket files I've recorded that the audio is always tagged at being 46.857FPS regardless of the video FPS selected.

Hi Ray.

Yes, different software can identify stuff incorrectly but will still read/play it fine, as you've said.

Also and as you've said, this issue with file splitting can happen at different times with different frame rates, or more precisely, at different bit rates.

If recording at 100Mb/s at any frame rate, the split will occur at roughly the same point in time. I say roughly as most cameras use an average that's VBR and not CBR. If you halve the bit-rate to 50Mb/s then you'll get twice as much time before the split, again regardless of resolution.

Usually, HD recording will split at twice the recorded length of UHD. This is usually because HD will use roughly half the bit rate of what UHD will.

I'm not sure why there's even the 4GB file split. This used to be because anything that used a file split didn't come under the classification of camcorder/video camera. This meant that in certain territories in the world, that particular classification didn't attract the same customs charges on import duties as a video camera. I'm not sure if this is still the same now but if it is it may explain a few things.

Until DJI fix this I guess the workaround for me is to not talk so much

Cheers,
Dave.   

I’ve noticed this only happens for me when Rocksteady is on, when it’s off the files after the split are still in sync.
Glad I found this post, at least I know it’s not just my unit doing it.

Dai Hughes Posted at 5-22 14:28
I’ve noticed this only happens for me when Rocksteady is on, when it’s off the files after the split are still in sync.
Glad I found this post, at least I know it’s not just my unit doing it.

Hi Dai.

Thanks for that, it's very helpful. In my example RS was on, so this sounds like the same issue you've noticed.
BTW. It may be the case that Oh-no's suggestion may be the case.

Cheers,
Dave.

David_Harry Posted at 5-22 14:34
Hi Dai.

Thanks for that, it's very helpful. In my example RS was on, so this sounds like the same issue you've noticed.

Hi Dave

If you also watch the clip back on the Osmo itself so it plays in one continuous stream, the audio stays synced.
Yes possibly todo with the latency, let’s hope it’s resolved soon!
Cheers
Dai

Dai Hughes Posted at 5-22 14:41
Hi Dave

If you also watch the clip back on the Osmo itself so it plays in one continuous stream, the audio stays synced.

Hi Dai.

I'll check that out next time I've got stuff on the Action. That footage was dumped off very soon after recording it and the card was cleared for another session.

Cheers,
Dave.

Dai Hughes Posted at 5-22 14:41
Hi Dave

If you also watch the clip back on the Osmo itself so it plays in one continuous stream, the audio stays synced.

Interestingly when watching back on the Osmo if you watch while it passes the split mark it stays in sync, but if you scrub the time line so you skip into what would be the second file, it’s then out of sync.

David_Harry Posted at 5-22 14:34
Hi Dai.

Thanks for that, it's very helpful. In my example RS was on, so this sounds like the same issue you've noticed.

Dave, I just guess, not jump to conclusion.


As I mentioned before when I first got the OP, most dash cams will start a new file 1 second before the previous one ends, the audio and video will not broken, they design this to prevent a missed second if any accident occurs and not recorded, DJI shall learn something from it.


Besides, if RS is the main cause of the latency of the video, that was rather serious not only on the live view at the screen but the final footage, wish  DJI addressed it and fix it soon, otherwise Go-Slow will laugh at them and say it is a Os-slow ..... and endusers suffers from non-usable footage, its is a a pain in the axx....

Dave, can you tell it happens at any resolution any frame rate OR it only happens when RS is turned on?

David_Harry Posted at 5-22 14:14
Hi Ray.

Yes, different software can identify stuff incorrectly but will still read/play it fine, as you've said.

"I'm not sure why there's even the 4GB file split. This used to be because anything that used a file split didn't come under the classification of camcorder/video camera. This meant that in certain territories in the world, that particular classification didn't attract the same customs charges on import duties as a video camera. I'm not sure if this is still the same now but if it is it may explain a few things."

Thank you for that reminder of a fact I'd completely forgotten
It could be, as the older reason for not producing larger files is now mainly redundant on newer systems.
This does need fixing as sometimes I need to record a whole concert with one camera in one take.  

Ray-CubeAce Posted at 5-22 23:27
"I'm not sure why there's even the 4GB file split. This used to be because anything that used a file split didn't come under the classification of camcorder/video camera. This meant that in certain territories in the world, that particular classification didn't attract the same customs charges on import duties as a video camera. I'm not sure if this is still the same now but if it is it may explain a few things."

Thank you for that reminder of a fact I'd completely forgotten

Hi Ray.

If this is still the case for customs, export etc. Then yes, it may well be the reason for it on the Action and Pocket. As you say, it's most certainly not down to that fact that either camera can't technically do long files.

Sometimes the excuse of safety in case of data loss is used or licenses for certain file/data formats, I'm not saying these are excuses by DJI but I've seen them used with other products.

I remember a similar issue back in the days of DV were certain devices couldn't record via their firewire interface, although they were technically capable and only play through it. Anything that recorded via firewire would have been categorised as a VCR.

It may still be the same today were a very expensive DSLR which can record video with the 4GB file limit has a lower customs charge compared to a video camera/camcorder that is cheaper.

Thing that gets me if this import duty thing is still the same, both the Action and Pocket are definitely video cameras, not stills cameras with video ability

Cheers,
dave.

David_Harry Posted at 5-22 23:46
Hi Ray.

If this is still the case for customs, export etc. Then yes, it may well be the reason for it on the Action and Pocket. As you say, it's most certainly not down to that fact that either camera can't technically do long files.

I agree.
I think there should only be tariffs on substandard products of poor quality. That base standards are met but could be above those standards with no penalty. Then maybe manufacturers would think twice about producing such items and consumers could buy with more confidence.
I don't think it was the only reason though. Originally wasn't there a file size limit some operating systems could cope with because of the FAT file system? I remember Cubase not being able to export file sizes of more than 4gig a long time ago.

Ray-CubeAce Posted at 5-23 04:36
I agree.
I think there should only be tariffs on substandard products of poor quality. That base standards are met but could be above those standards with no penalty. Then maybe manufacturers would think twice about producing such items and consumers could buy with more confidence.
I don't think it was the only reason though. Originally wasn't there a file size limit some operating systems could cope with because of the FAT file system? I remember Cubase not being able to export file sizes of more than 4gig a long time ago.

Hi Ray.

If there were tariffs for substandard products no one  would be buying actioncams

It's been a very long time since data format/file size was an issue. Back in the day with Cubase I think the issue was pre windows NT. I believe NTFS was introduced with one of the versions of Win NT. Since then MS have used NTFS as it's main file system/format for most of its OSs.

But even outside of NTFS, EX-FAT has been around for ages and other large file addressable formats, certain Ext ones and others, some of which don't require a payed license or are cheap to use.

Cheers,
Dave.

David_Harry Posted at 5-23 05:07
Hi Ray.

If there were tariffs for substandard products no one  would be buying actioncams

If there were tariffs for substandard products no one  would be buying actioncams

Top Gear has used them for years.

Yes, possibly Win98.

Hi All

I’ve done some testing on mine

So far...
Audio stays in sync ...
1080p 30 and 60 fps with RS on or off
2.7k 30fps RS off
4K 30fps RS off

Audio out of sync
2.7k 30 FPS RS on ... words and mouth do not line up at all during normal speech ( Live Dave’s example)
4K 30 FPS RS  ....  this isn’t as bad as the 2.7k sync, its only a tiny bit out.

Dai

With the  2.7k clips in premier pro, the audio for the second clip needs advancing around .45 seconds for it to get synced.
The footage looks like it flows seamlessly but the audio is missing this amount yet it starts playing when the clip starts.... the delay caused by RS does look to be around the same amount which is interesting ( only eyed it not measured correctly) but not sure why different resolutions give me different experiences.

Anyone from DJI reading this topic and can confirm its being looked into?

Cheers

Dai Hughes Posted at 5-23 11:56
With the  2.7k clips in premier pro, the audio for the second clip needs advancing around .45 seconds for it to get synced.
The footage looks like it flows seamlessly but the audio is missing this amount yet it starts playing when the clip starts.... the delay caused by RS does look to be around the same amount which is interesting ( only eyed it not measured correctly) but not sure why different resolutions give me different experiences.

Hi Dai.

Thanks for all that information it's really helpful.

I was at 25 FPS RS D-Cine Dewarp 4K/UHD and also using the MP4 wrapper/container, I'll try MOV if  I get a chance as there are muxing and timing differences between MP4 and MOV.

In my recordings the audio can be re-synced in the second half by a delayed offset, this means there is a short but very noticeable gap in the audio as part 1 runs into part 2.

I've also used some demux tools and demuxed the MP4 to its elementary streams. The results are that there is no extra hidden audio information to be retrieved, at least in my case, this may be different for other setup scenarios.

If I get time I'll try and do a HDMI screen capture showing my process in detail. I'll post this to YouTube and here just in case anyone outside of the forum may have any suggestions.

Although with all that said and as Dai is also saying, a bit of input from DJI wouldn't go amiss.

Thanks again Dai.

Cheers,
Dave.  

Dai Hughes Posted at 5-23 11:56
With the  2.7k clips in premier pro, the audio for the second clip needs advancing around .45 seconds for it to get synced.
The footage looks like it flows seamlessly but the audio is missing this amount yet it starts playing when the clip starts.... the delay caused by RS does look to be around the same amount which is interesting ( only eyed it not measured correctly) but not sure why different resolutions give me different experiences.

Hi Dai and Ray.

Check this thing I've just done. Not only does it prove the point that audio information is missing but there's a real funny irony going on as to where I seem to be ending my takes

Cheers,
Dave.

Haha great timing, amused me too!
  Great tests too Dave, proves with out doubt audio is being lost.

Before I found this forum I tweeted the issue and I’ve had a response from DJI Support
“Thanks for your feedback, the issue has been reported to our engineers for attention, we will keep optimising the audio.Please note the future firmware and App update”

I’ve replied with the title of this topic saying there are examples and asked if somebody can acknowledge on here too.
Dai

Dai Hughes Posted at 5-23 22:19
Haha great timing, amused me too!
  Great tests too Dave, proves with out doubt audio is being lost.

I doubt the mods can find it.
I logged in this morning and no posts were visible to me.
Although I know how to navigate the new forum, it seems a mess and long-winded for navigation now.

Glad to know the faults were identified, wish DJI can fix it ASAP .......

Is this solved? i'm having the same issue... and I can't find a way to solve this... :/

Having same issue with osmo action, I returned the camera