Hit a snag using Osmo Pocket with MEP/VPX

Recycler wrote on 4/11/2019, 3:21 PM

I am trying out my DJI Osmo Pocket at HD and at Ultra-HD and am delighted with it. I'm not a blogger, and my long term use for this camera would be as part of my kit for multi-cam recording of concerts and lectures, presently done with a raft of Panasonic x920s at 1080p/50. Although I have VPX, I've posted here because since VPX can no longer handle multi-cam work I've dropped back to MEP, which still works fine in multi-cam.

The problem is this. Both the Osmo Pocket and the Panny x920s use exFAT-formatted cards. But the Osmo uses a different MPG profile to the X920 AND an MP4 wrapper, whilst the x920s (perhaps crucially) outputs a transport stream. As a result the facility under File menu "record audio / images /video ..." does not concatenate a series of 4 GB files from the Osmo's SD card like it does the x920's files. As a result, you a get sequence of butted up, but separate media files on the timeline. A typical gap in the audio was 140 mS, definitely audible. With my kind of work (long, uninterruptible takes) syncing that to other cameras by hand is going to be a right pain.

Is there any way to avoid this? I can completely understand why DJI made their decision choice for MP4, because the quality/data ratio is much higher, and the product is by nature intended for short takes (blogging). If this a fundamental problem it's a crying shame, because the Osmo is ideal as an unobtrusive self-controlled follow-cam for gently tracking lecturers as they pace about, and can be directed remotely along a line of soloists (say) via a wifi connection. A terrific product in my opinion - except for the issue outlined.

Any thoughts, anyone please? - Mike -

Comments

CubeAce wrote on 4/11/2019, 5:49 PM

I've seen this mentioned on the DJI site from other Osmo Pocket users. Some of the audio problems seem to come from which micro SD card spec you use so I tested if it happened with the highest spec cards I have which are well within the secified requirements for my Osmo Pocket. The result was roughly the same as yours.

I can't see any way around this without losing frames and possible video sync unless you use the audio stream from one of your other cameras.

Ray.

RogerGunkel wrote on 4/11/2019, 6:03 PM

I regularly shoot multi cams for weddings and stage shows using Panasonic FZ1000s in 4k and 4k Gopro clones. There are sometimes small gaps between files, but I overcome that quite easily by using the audio synch facility to synch the audio from the individual clips to a master audio clip first, then continuing with the normal editing.

Roger

Recycler wrote on 4/12/2019, 2:16 AM

Thank you CubeAce & RogerGunkel. Yes, I would always need to use an external source as master audio, since the Osmo's built-in mics produce mono and are not that brilliant, particularly when mounted in the Osmo's WiFi base. In the past, I never had much luck with Magix's audio sync facility, but perhaps it has improved since I last tried. I'll certainly give it a go. Thanks again.

emmrecs wrote on 4/12/2019, 4:02 AM

@Recycler

Have a look at tsMuxer. I use it to seamlessly join video files produced by my Canon AVCHD cameras, which always start a "new" file about every 15 minutes or so. It's free, so nothing lost if it doesn't work for you, but I have successfully joined up to 5 or 6 separate files to create one continuous file without those annoying "breaks".

One note of caution: it's not the easiest of softwares to understand exactly what to do, so if you're stuck, feel free to post back!

HTH

Jeff

Recycler wrote on 4/12/2019, 4:09 AM

Jeff: good idea! I used tsMuxer myself literally for years until I migrated to Magix Video editors and found the "Import" function worked so well - but seemingly only for TS, not mp4 packaged formats. I'll download a fresh copy and have a go at remembering (as you say) its slightly unwelcoming facade!

Thanks. - Mike -

CubeAce wrote on 4/12/2019, 6:28 AM

@Recycler

Hi Mike.

I don't know if you are aware or not but if you go to the mixer and take away one channel of the audio from the Osmo Pockets audio the result sounds much cleaner and usable. Both channels are down on audio as you are probably aware but if you remove the lowest volume one and boost the other and pan it to a central position the result is a much cleaner sound. The noise floor when boosted is still remarkably low and clean. The audio adaptor currently is not much better in use but with the right microphone can be made a bit louder than the internal mics and have slightly more dynamic range.

We are still waiting at the Dji users site to see if a stereo output will be available with a firmware fix, along with a signal boost. There does appear to be two discrete audio channels but they have been configured to reduce wind and handling noise and not reconfigured when using the audio adaptor.

I don't have the wi-fi base but haven't heard anyone say the audio is worse when using it.

Recycler wrote on 4/12/2019, 6:37 AM

Thanks Ray, I wasn't aware - I'll try the separate channels. I haven't yet built up enough experience with OP to be certain about anything yet! My comment about the wifi base was simply that the bottom of the OP sits well inside it, covering the lower (noise cancelling) mic hole. - Mike -

CubeAce wrote on 4/12/2019, 7:47 AM

@Recycler

That may not be a bad thing. 😉

Yup.If you can separate the audio tracks in MEP you will see almost identical waveforms most of the time but with some phase variance, which is why it sounds so appalling in the higher frequencies.

This screenshot was taken in Cubase as I found the audio easier to manipulate but I think you can manipulate left and right channels in MEP by using the FX sends 1 & 2. I'm sure if I'm wrong, someone can correct me.