P4K Headphone Delay

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Jim Giberti

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P4K Headphone Delay

PostMon Dec 31, 2018 5:37 pm

Simple questions for Blackmagic:
Are you aware of this glaring problem?
What is the timeline to address it?

Finally having decent audio capabilities in a small BM camera is great.
Having the useability ruined because of a ??? headphone delay is incomprehensible.

Thank you.

PS, I've reached out to BM support about this and will report back on any response.
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Australian Image

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Re: P4K Headphone Delay

PostMon Dec 31, 2018 8:02 pm

It could be your setup. I just tested mine and no delay whatsoever.
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Fornez

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Re: P4K Headphone Delay

PostMon Dec 31, 2018 8:06 pm

I have this headphone delay between the left and right channels, the actual audio recording is fine
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Jim Giberti

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Re: P4K Headphone Delay

PostTue Jan 01, 2019 9:58 am

Australian Image wrote:It could be your setup. I just tested mine and no delay whatsoever.


Really? When you connect a mic to the XLR input and listen through headphones , you don't hear a delay vs the live sound?

I just got a response from BM claiming the delay in monitoring is by design - they've designed the headphone output to sync with playback in camera. Which, frankly, is absurd. It suggests that a primary requirement of recording audio isn't monitoring the signal through headpnones.

Listening back to recorded takes through headphones would, one would think, be a low priotity in comparison to monitoring your input during recording.
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Robert Niessner

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Re: P4K Headphone Delay

PostTue Jan 01, 2019 10:33 am

You are listening to the audio signal after processing and therefore a slight delay is normal. This is the case on any broadcast camera having the ability to monitor the signal after processing (which is what you normally want to do).
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Australian Image

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Re: P4K Headphone Delay

PostTue Jan 01, 2019 7:41 pm

Jim Giberti wrote:
Australian Image wrote:It could be your setup. I just tested mine and no delay whatsoever.


Really? When you connect a mic to the XLR input and listen through headphones , you don't hear a delay vs the live sound?


That's the difference, I use the 3.5mm jack. I admit that designing the audio syncing to playback is nuts.
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Jim Giberti

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Re: P4K Headphone Delay

PostTue Jan 01, 2019 9:53 pm

Robert Niessner wrote:You are listening to the audio signal after processing and therefore a slight delay is normal. This is the case on any broadcast camera having the ability to monitor the signal after processing (which is what you normally want to do).



What do you mean by "after processing" Robert?
The mic plugs into the XLR to the preamp without any processing.

More importantly BM doesn't see it that way. They have specifically synched to playback rather than to live recording where headphone monitoring is "what you normally do".

Why do you need sycnched audio only on playback - you can't delete a clip in camera so who uses that commonly?...what's the purpose versus knowing that you're getting a clean signal at any given point in real time - not after the fact.

Why is it different than any other recording device - say a prosumer H4N?

I'm a pretty experienced audio producer and I definitely don't consider it normal to have a delay while recording anything.

In the recordng studio it's called latency and it's a problem when tracking if the buffer isn't properly set.

They simply need to provide an option to record, without latency, while actually using the headphone output.
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Robert Niessner

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Re: P4K Headphone Delay

PostTue Jan 01, 2019 11:36 pm

Jim Giberti wrote:
Robert Niessner wrote:You are listening to the audio signal after processing and therefore a slight delay is normal. This is the case on any broadcast camera having the ability to monitor the signal after processing (which is what you normally want to do).



What do you mean by "after processing" Robert?
The mic plugs into the XLR to the preamp without any processing.


Yes, but there is a preprocessing going in for the video part, which always causes a slight delay. Because the audio is synched to the video timing it has the same monitoring delay. Some broadcast cameras have the ability to bypass that for monitoring so you get the signal directly when set so.


Jim Giberti wrote:Why is it different than any other recording device - say a prosumer H4N?

They simply need to provide an option to record, without latency, while actually using the headphone output.


A prosumer H4N doesn't have to process video data. I am sure the H4N also has a slight delay on the monitoring side, but you won't notice because it is too short.

Video + audio is more complex than just audio alone.
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Jim Giberti

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Re: P4K Headphone Delay

PostTue Jan 01, 2019 11:52 pm

Jim Giberti wrote:Video + audio is more complex than just audio alone.


Of course I know this Robert but you're not talking to my point.

What is the inherent value of only having audio synched to playback?

When would you need that in day to day production versus the obvious professional need to monitor live without latency?

I don't have any other gear (we have severak kits) wher there is or has ever been latency on monitoring live.

It makes no sense. It should be synched to live recording - listening back in camera is pretty useless by comparison.

Makes no sense to me.
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Robert Niessner

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Re: P4K Headphone Delay

PostWed Jan 02, 2019 1:33 am

Jim Giberti wrote:
Jim Giberti wrote:Video + audio is more complex than just audio alone.


Of course I know this Robert but you're not talking to my point.

What is the inherent value of only having audio synched to playback?

When would you need that in day to day production versus the obvious professional need to monitor live without latency?

I don't have any other gear (we have severak kits) wher there is or has ever been latency on monitoring live.

It makes no sense. It should be synched to live recording - listening back in camera is pretty useless by comparison.

Makes no sense to me.


I've already explained to you above why the audio is clocked to the video and why this leads to a delay. The delay on my PCC4K is quite short (~1.5 frames) and you get used to it fast. The audio IS synced to live recording - why do you think it isn't?

Which other video gear do you have which doesn't have this delay?
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Robert Niessner

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Re: P4K Headphone Delay

PostWed Jan 02, 2019 1:40 am

We had a lengthy discussion about the same topic here:
viewtopic.php?f=2&t=63256
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Jim Giberti

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Re: P4K Headphone Delay

PostThu Jan 03, 2019 6:42 am

Robert wrote:I've already explained to you above why the audio is clocked to the video and why this leads to a delay.


And I've explained to you why it's unacceptable by pretty much any standard.

Robert wrote:Which other video gear do you have which doesn't have this delay?


I don't have any latency issues with any gear or in any of my three studio rooms.
I don't know any pro who does.
What pro audio gear do you have that has monitoring delay?


Please Robert, this isn't just me.
I've had two different team members ask what to do about it on shoots just this week.
They're not confused. They too have been doing this for years.

Here's a new review of the camera. Watch from around 4:55
https://www.youtube.com/watch?time_cont ... 5bH1runF-U
Are they confused too?
I'm kind of amazed that you find this normal/acceptable.
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Robert Niessner

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Re: P4K Headphone Delay

PostThu Jan 03, 2019 9:34 am

Ok, Jim. From your answer I assume you have no other own video gear for comparison. You are projecting your experience from your audio gear into video gear and how it should work. I told you why there is the delay and why we have to accept it. I am not happy with it either, but I accepted it and moved on - because in reality it is not a big deal for me. I have worked professionally with those delays the last 18 years perfectly fine. Just use closed headphones, get used to it and the problem is gone.

As far as we know all BMD cameras have no secondary audio circuits to bypass the synced video processing for giving you undelayed audio. Video processing is much more CPU intense than audio processing and introduces a delay.

This has been the case with all professional broadcast cameras I have ever worked with. Some had the ability to bypass the signal into a secondary circuit, most of them didn't.
You can either accept this as it is, or continue to argue with me about something we can't change yet.
I am sure in the next ten years low power CPUs will have increased enough in speed to make the delay unnoticed.
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Denny Smith

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Re: P4K Headphone Delay

PostThu Jan 03, 2019 6:59 pm

Robert is spot on, and only a few ENG cameras I have used have a post/pre audio switch to allow monitoring of audio either way (which requires additional hardware in the camera). Most Consumer cameras like DSLRs do not monitor post audio, they only pre audio being fed into the camera, so no delay as you are watching the scene directly, not with your eyes glued to a monitor once the shot is framed. To be sure your Camera is actually recording the audio correctly, you need to monitor the audio post, sync’d with the EFV or monitor image, not the live action.
Cheers
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Jim Giberti

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Re: P4K Headphone Delay

PostThu Jan 03, 2019 9:06 pm

Robert Niessner wrote:Ok, Jim. From your answer I assume you have no other own video gear for comparison. You are projecting your experience from your audio gear into video gear and how it should work. I told you why there is the delay and why we have to accept it. I am not happy with it either, but I accepted it and moved on - because in reality it is not a big deal for me.


That's about as far from a correct assumption as you could make Robert.

As I've stated, I own a creatve/production company and have for many years. We have and have always had several camera systems as well as a small production studio.

I've personally designed and built several recordings studios and film/video edit rooms. As a creative director I'm always on set, in the field and very often behind a camera.

I've never experienced this kind of latency in any camera. For one simple, basic example - we used to have a closet full of Canon XL1s at one time doing a lot of ski industry and olympic film and promotional work. On a fairly "prosumer" camera like that, for instance, their was never latency.

Again, twice in one week two professionals on my team for years, put on the phones on the P4K and said something like, "this is unuseable".

Did you have a chance to look at the section in the new review I linked to?

I'm not unique seeing this as a problem and wanting it addressed for our use.

Let's just leave it that I and obvioulsy others, have a different level of expectation regarding this - as well as experience that's different from yours.

It's all good (except for the P4K audio latency problem. ;)
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Robert Niessner

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Re: P4K Headphone Delay

PostThu Jan 03, 2019 11:22 pm

Jim Giberti wrote:
Robert Niessner wrote:Ok, Jim. From your answer I assume you have no other own video gear for comparison. You are projecting your experience from your audio gear into video gear and how it should work. I told you why there is the delay and why we have to accept it. I am not happy with it either, but I accepted it and moved on - because in reality it is not a big deal for me.


That's about as far from a correct assumption as you could make Robert.

As I've stated, I own a creatve/production company and have for many years. We have and have always had several camera systems as well as a small production studio.

I've personally designed and built several recordings studios and film/video edit rooms. As a creative director I'm always on set, in the field and very often behind a camera.

I've never experienced this kind of latency in any camera. For one simple, basic example - we used to have a closet full of Canon XL1s at one time doing a lot of ski industry and olympic film and promotional work. On a fairly "prosumer" camera like that, for instance, their was never latency.

Again, twice in one week two professionals on my team for years, put on the phones on the P4K and said something like, "this is unuseable".

Did you have a chance to look at the section in the new review I linked to?

I'm not unique seeing this as a problem and wanting it addressed for our use.

Let's just leave it that I and obvioulsy others, have a different level of expectation regarding this - as well as experience that's different from yours.

It's all good (except for the P4K audio latency problem. ;)


Well, regarding the Canon XL1s:

The headphone amp is connected before the ADC. If you wanted to monitor what's actually printing to tape, you had to use the FireWire output into a laptop.

I actually owned 2 Canon XM-2 which are almost identical to the XL1s.

The manual of my Canon XF305 explicitly states that you can switch the headphone output to realtime monitoring, but warns that even then it will have a delay.

I have had a look at the section of the review you have linked to and there is nothing new to learn. I own the UM46k, the PCC4K, the BMCC, my colleague the UMP and all have the delay and nobody ever had a problem with that listening to the headphones.

So if someone from your team has a problem with that, rest assured that together with closed headphones with good isolation you can get used to it easily.
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Robert Niessner

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Re: P4K Headphone Delay

PostMon Feb 04, 2019 11:39 pm

Good news:
BMD has stated that with the new firmware 6.1 the headphone delay has been reduced.
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Denny Smith

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Re: P4K Headphone Delay

PostTue Feb 05, 2019 1:37 am

I have owned and used all the Canon XLs, and they all had audio monitoring from the camera preamp, not list, as Robert indicated, so yes, no latency when you are not hearing the post ADC audio or what is beeing recorded to tape, this will have some delay, but is a feature not available on the XLs.

Even a stand-alone ADC will have some delay between the analog audio going in and the converted digital audio coming out, the better the ADC, the lower the latency time, which equates into a greater cost.
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ted ramasola

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Re: P4K Headphone Delay

PostTue Feb 05, 2019 1:56 am

Good news is the headphone delay seem to have been fixed on this new 6.1 firmware when plugging mic via 3.5 jack.
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Jim Giberti

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Re: P4K Headphone Delay

PostTue Feb 05, 2019 3:31 am

It's appreciated that they addressed the issue.
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bcortesl

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Re: P4K Headphone Delay

PostMon Aug 12, 2019 3:04 am

I still have some little delay. Any one have it too? It is a bit disgusting. When monitoring audio from a Sony, it works perfect, I do it on my P4k and it is annoying.

yeah, I have the latest vesrion.

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Phil999

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Re: P4K Headphone Delay

PostMon Aug 12, 2019 6:33 am

if audio monitoring without latency is important, you can always route the microphone into a small mixer first where you can plug the headphone, and from the mixer into the camera.

Another option is to use a separate microphone that is not connected to the camera, for monitoring only.
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Denny Smith

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Re: P4K Headphone Delay

PostMon Aug 12, 2019 4:50 pm

You could, but neither solution is going to be monitoring the audio that has been recorded/processed in camera or recorder. Monitoring pre processed audio is ok in many situations, if level meters are set correctly and you are using a good limiter, but many times, you need to monitor the audio post recording, to be sure what is going in, comes out correctly.

BM Cameras have some audio delay because they are monitoring post processed audio as it is recorded. ;)
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bcortesl

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Re: P4K Headphone Delay

PostWed Aug 14, 2019 3:15 am

Denny Smith wrote:You could, but neither solution is going to be monitoring the audio that has been recorded/processed in camera or recorder. Monitoring pre processed audio is ok in many situations, if level meters are set correctly and you are using a good limiter, but many times, you need to monitor the audio post recording, to be sure what is going in, comes out correctly.

BM Cameras have some audio delay because they are monitoring post processed audio as it is recorded. ;)


Now it make sense! So, never, never will be a ""perfect audio"" without delay.

Well, that's all for me in this post!

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