3-4 channel audio for XL H1

Johan Forssblad · August 13th, 2006, 09:26 AM

Hi, I would appreciate some recommendations for improvement on the sound quality with the XL H1.
Background:
I like to have easy managed equipment which could be operated by a crew not larger than two. I shoot with one XL H1, for instance a museum where they show people around or an orchestra or wedding party and similar. I aim to get a quality superior to what most ameteur can make but it doesn't need to reach broadcast quality.

I have found out I need more than the stereo microphone onboard the H1. For instance I'm filming a person telling a joke, then I turn around to get the laughing public. This destroys the audio track from the camera when the speaker suddenly are in the muted zone behind the camera. Thats why I need one or two additional audio tracks which are more continously recording what's going on. When I reposition the camera or framing, I edit in still photos, details and others which are shot later.

Which is the way to go:

1. Use the four channel mode on the camera and accept 12-bit sound instead of 16 bits. Connect channel 3 and 4 to one or two wireless receivers and have lavalier mics and/or boom mic with transmitters.
Audio will be neglected due to lack of possibility to shoot and monitor audio at the same time. Camera has to run all the time to not miss any sound. I'm afraid the audio will not have quality enough especially because the photographer cannot keep the audio level correctly adjusted and for safety has to use a low level which is not good with only 12 bit dynamic range. "EDIT: Wrong, see A.J. Lange´s comment below - the audio is 16 bit in HDV even when using 4 channels!"
According to other threads capture is time consuming requiring to capture twice to get channel 3 and 4 to Final Cut Pro.

2. Use a separate solid state recorder like M-Audio Microtrack 24/96 or Sound Devices 702T to collect two tracks with a steady sound from boom mike or lavalier with wireless. One person operating these sound channels. Timecode to sync the tracks in post.

3. Leave a solid state recorder like a Microtrack 24/96 in the pocket of the actor with lavalier. Omit wireless. Hope the sound setting is good enough.
-

The XL H1 is fine but often it will not pickup the right sound because it is too far away from a speaker or you like to have an orchestra filmed with sound from the conductor postion and then use the onboard mic more sparingly when you shot closeups from the side etc.
I must also add that I like to keep the weight and size down of the equipment especially when travelling. It is getting harder and harder these days to carry all the stuff in the hand luggage when flying ...

Any comments will be appreciated! /Johan

A. J. deLange · August 13th, 2006, 10:52 AM

Just a reminder here that when recording 4 channels the H1 drops to 12 bit audio at a lower sample rate (32 kHz) only in SD mode. In HD mode the bit depth (16) and sample rate (48 kHz) stay the same but the total bit rate out of the CODEC stays the same so that each channel is subject to twice the compression when 4 channels are being recorded relative to the amount of compression when 2 channels are being laid down. Whether that extra compression is annoying/noticeable or not would be a judgement the individual would have to make.

Given this situation recording extra, or all, channels on a separate machine is appealing as a way to get better sound (straight PCM, bit depths greater than 16, sample rates higher than 48 kHz). Attendant with this approach is the higher cost (especially for 4 channels) and the need to synchronize sampling and time code (requiring two cables be run between camera and recorder) for best results.

A somewhat less expensive approach, assuming that you already have a laptop computer, is to obtain one of the multi channel interfaces that convert mic and/or line signals to digital and record them to the hard disk of the laptop. You still need to deal with the sync problems and now have three pieces of gear to fumble with in the field i.e. camera, interface and computer.

Johan Forssblad · August 13th, 2006, 02:30 PM

Thank you A.J for correcting me and sharing your opinions.
I hadn't noticed it is 12 bit in SD but 16 bit in HD. Good.
I think sound quality is one of the most difficult things to discuss, at least when those audio purists get involved ...
So the dumb question "is the XL H1 4 channel audio good enough" will probably end up in confusion when answers are dropping in.

However, I like to be able to travel around without computer. Even if a computer is quite versatile these days I prefer to have a dedicated recorder without extra conversion boxes, phantom power, power supply etc. The unit must be easy to move around without risk of breaking the LCD, must work inside a bag for moisture protection, hang over the shoulder so we can move easily, operate without freezing. The computer is far from an ideal piece of field equipment in my opinion.

I also don't want sync cables between the recorder and camera. More freedom is preferred. What about a simple clapper? Aren't the camera clock and audio recorder stable enough to not drift away nowadays?
Any who have tried? How much drift will you get? Can you record an orchestra for one hour and still be at the same 1/16 tone? If so, I think it is good enough for my purpose. Chime in please! /Johan

A. J. deLange · August 14th, 2006, 01:53 PM

Yes, the computer solution is definitely clumsy anywhere other than in a studio setting. The recorders, conversely, often come with a shoulder strap so that it is even conceivable that one guy could run recorder and camera. In the over-the-shoulder configuration the cables between camera and recorder are not so troublesome but they do present the opportunity for mistakes because setup is a little more complicated.

The accuracy held between separate camera and recorder depends on the individual itmes accuracy and stability. It's really only possible to determine how a recorder/camera pair will perform by test. Keeping both at the same temperature and making sure that each has fully charged batteries may help. Generally speaking I would think agreement to within a frame (20 mS) over 15 minutes should be realizeable. At 1/4note = 120 bpm a quarter note is 500 mS and so a 16th (semiquaver) would be 125 mS or about 6 frames in duration. You could conceivably be much better than this and you could also do worse. Luck plays into it as does the age of the equipment. Crystals drift in frequency over time.

August 13th, 2006, 09:26 AM	#1
Johan Forssblad Major Player Join Date: Nov 2005 Location: Vittsjö, SKÅNE, SWEDEN Posts: 266	3-4 channel audio for XL H1 - recommendations please! Hi, I would appreciate some recommendations for improvement on the sound quality with the XL H1. Background: I like to have easy managed equipment which could be operated by a crew not larger than two. I shoot with one XL H1, for instance a museum where they show people around or an orchestra or wedding party and similar. I aim to get a quality superior to what most ameteur can make but it doesn't need to reach broadcast quality. I have found out I need more than the stereo microphone onboard the H1. For instance I'm filming a person telling a joke, then I turn around to get the laughing public. This destroys the audio track from the camera when the speaker suddenly are in the muted zone behind the camera. Thats why I need one or two additional audio tracks which are more continously recording what's going on. When I reposition the camera or framing, I edit in still photos, details and others which are shot later. Which is the way to go: 1. Use the four channel mode on the camera and accept 12-bit sound instead of 16 bits. Connect channel 3 and 4 to one or two wireless receivers and have lavalier mics and/or boom mic with transmitters. Audio will be neglected due to lack of possibility to shoot and monitor audio at the same time. Camera has to run all the time to not miss any sound. I'm afraid the audio will not have quality enough especially because the photographer cannot keep the audio level correctly adjusted and for safety has to use a low level which is not good with only 12 bit dynamic range. "EDIT: Wrong, see A.J. Lange´s comment below - the audio is 16 bit in HDV even when using 4 channels!" According to other threads capture is time consuming requiring to capture twice to get channel 3 and 4 to Final Cut Pro. 2. Use a separate solid state recorder like M-Audio Microtrack 24/96 or Sound Devices 702T to collect two tracks with a steady sound from boom mike or lavalier with wireless. One person operating these sound channels. Timecode to sync the tracks in post. 3. Leave a solid state recorder like a Microtrack 24/96 in the pocket of the actor with lavalier. Omit wireless. Hope the sound setting is good enough. - The XL H1 is fine but often it will not pickup the right sound because it is too far away from a speaker or you like to have an orchestra filmed with sound from the conductor postion and then use the onboard mic more sparingly when you shot closeups from the side etc. I must also add that I like to keep the weight and size down of the equipment especially when travelling. It is getting harder and harder these days to carry all the stuff in the hand luggage when flying ... Any comments will be appreciated! /Johan Last edited by Johan Forssblad; August 13th, 2006 at 02:08 PM.

August 13th, 2006, 10:52 AM	#2
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Just a reminder here that when recording 4 channels the H1 drops to 12 bit audio at a lower sample rate (32 kHz) only in SD mode. In HD mode the bit depth (16) and sample rate (48 kHz) stay the same but the total bit rate out of the CODEC stays the same so that each channel is subject to twice the compression when 4 channels are being recorded relative to the amount of compression when 2 channels are being laid down. Whether that extra compression is annoying/noticeable or not would be a judgement the individual would have to make. Given this situation recording extra, or all, channels on a separate machine is appealing as a way to get better sound (straight PCM, bit depths greater than 16, sample rates higher than 48 kHz). Attendant with this approach is the higher cost (especially for 4 channels) and the need to synchronize sampling and time code (requiring two cables be run between camera and recorder) for best results. A somewhat less expensive approach, assuming that you already have a laptop computer, is to obtain one of the multi channel interfaces that convert mic and/or line signals to digital and record them to the hard disk of the laptop. You still need to deal with the sync problems and now have three pieces of gear to fumble with in the field i.e. camera, interface and computer. Last edited by A. J. deLange; August 13th, 2006 at 11:54 AM.

August 13th, 2006, 02:30 PM	#3
Johan Forssblad Major Player Join Date: Nov 2005 Location: Vittsjö, SKÅNE, SWEDEN Posts: 266	Thank you A.J for correcting me and sharing your opinions. I hadn't noticed it is 12 bit in SD but 16 bit in HD. Good. I think sound quality is one of the most difficult things to discuss, at least when those audio purists get involved ... So the dumb question "is the XL H1 4 channel audio good enough" will probably end up in confusion when answers are dropping in. However, I like to be able to travel around without computer. Even if a computer is quite versatile these days I prefer to have a dedicated recorder without extra conversion boxes, phantom power, power supply etc. The unit must be easy to move around without risk of breaking the LCD, must work inside a bag for moisture protection, hang over the shoulder so we can move easily, operate without freezing. The computer is far from an ideal piece of field equipment in my opinion. I also don't want sync cables between the recorder and camera. More freedom is preferred. What about a simple clapper? Aren't the camera clock and audio recorder stable enough to not drift away nowadays? Any who have tried? How much drift will you get? Can you record an orchestra for one hour and still be at the same 1/16 tone? If so, I think it is good enough for my purpose. Chime in please! /Johan

August 14th, 2006, 01:53 PM	#4
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Yes, the computer solution is definitely clumsy anywhere other than in a studio setting. The recorders, conversely, often come with a shoulder strap so that it is even conceivable that one guy could run recorder and camera. In the over-the-shoulder configuration the cables between camera and recorder are not so troublesome but they do present the opportunity for mistakes because setup is a little more complicated. The accuracy held between separate camera and recorder depends on the individual itmes accuracy and stability. It's really only possible to determine how a recorder/camera pair will perform by test. Keeping both at the same temperature and making sure that each has fully charged batteries may help. Generally speaking I would think agreement to within a frame (20 mS) over 15 minutes should be realizeable. At 1/4note = 120 bpm a quarter note is 500 mS and so a 16th (semiquaver) would be 125 mS or about 6 frames in duration. You could conceivably be much better than this and you could also do worse. Luck plays into it as does the age of the equipment. Crystals drift in frequency over time.