canon XLHI ch 4 audio

[Mike Kujbida]

Unfortunately Vegas, like most NLEs, can only see 2 audio channels.
If you want all 4, check out Scenalyzer.
A demo version is available.

[Leslie Wand]

why would you record 4 channels of sub-standard sound?

leslie

[Prolog]

what do you mean by 4 channels of substandard sound?

[Prolog]

It seems that Canon neglected to include a switchable output for audio. So, channels 3-4 are incompatable with every NLE. If you put audio on either of those channels, you cannot access them for video editing. If that’s really the case, it’s a dumb trap for XLH1 owners. The solution is throw away the stereo camera mic, buy a mono, wire it into the rear XLR and then put your lav into audio2. Then you have 2 discreet audio channels that can be captured by any NLE. Just like real professional cameras.

It’s so weird that Canon put so much effort into the visual aspects of the camera, then put together a simply weird and convoluted audio system that can’t make up its mind whether its an amateur or pro machine. From various forums it sounds like pro users have been complaining about this for years.

Let it be said here: Shame on Canon for its rinky-dink approach to audio for video!

[Leslie Wand]

The most common format is stereo 48 kHz sampling. In this mode two channels of 16-bit samples are recorded at a frequency of 48 kHz. These are the same specifications used by DAT audio recorders and provide a theoretical audio frequency range of 0 Hz to 24 kHz — well beyond the range of normal human hearing (20 Hz to 20 kHz).

DV also has a 44.1 kHz 16-bit stereo recording mode. That mode is the same as that which is employed on audio CDs and has an audio frequency range of 0 Hz to 22 kHz. This mode is often labeled “44 kHz”.

Finally the DV format supports a mode with four channels of 32 kHz 12-bit audio.

The table below lists the various DV audio modes.

sampling frequency sample size number of channels equivalent quality
48 kHz 16-bit (linear) 2 DAT audio 0 Hz – 24 kHz
44.1 kHz 16-bit (linear) 2 CD audio 0 Hz – 22.05 kHz
32 kHz 12-bit (non-linear) 4 MiniDisk 0 Hz – 16 kHz

The original multimedia system that supported Microsoft’s Video for Windows system only had support for 11 kHz, 22 kHz and 44.1 kHz audio sampling frequencies. These frequencies corresponded to the audio modes supported by typical sound cards in PCs. Subsequently Microsoft introduced the Audio Compression Manager which included a Sound Mapper to resample on the fly from any given audio sampling frequency to one which is supported by the available sound card. Thus all modern Windows PCs can playback stereo audio recorded in any of the DV audio modes even if the computer’s audio hardware doesn’t directly support the mode. But many Windows applications that use only the original Video for Windows programming interfaces still only support creating AVI clips using the 44.1 kHz DV audio mode.

Ideally you don’t want to have to resample your DV audio, but if you should have to, for example, if different DV clips are recorded using different modes or you must use an application that only supports 44 kHz, you want that resampling to be high-quality. High-quality resampling audio from one sampling frequency to another requires good software. Without it harmonic distortion is introduced into to the audio signal which usually manifests itself as objectionable high-frequency ringing.

[Prolog]

This is all good information, but my immediate problem is that I recorded my main audio on channel 4, and I cannot get either Sony Vegas Or Premier Pro, the two editing programs I have to recognize and capture channel 4– just 1 and 2. I’m looking for a solution to capture channel 4. Evidently some editors/cards will capture it. But I just need a firewire capture application that will make an .avi with the 4 channels of audio.

Someone suggested scenealyzer, but I don’t see anything about 4 channels in their documentation; and it did not automatically recognize anything except 1 and 2.

Thanks for your help.

[Edward Troxel]

[prolog] “Someone suggested scenealyzer, but I don’t see anything about 4 channels in their documentation; and it did not automatically recognize anything except 1 and 2.”

In the scenalyzer preferences, you have to turn on 4-channel capture. The second two channels will then be captured into a WAV file with the same name as your AVI file.

Edward Troxel

[Rob Mack]

Normally we record mic and boom on channels 1-2. I’ve never seen anyone use a stereo mic professionally, but then I’m usually lighting and stay out of the sound person’s business (Don’t want to be sucked in, too many hats for one head.)

As leslie points out, if you record 4-channel audio on DV25 you take a sample rate hit on all channels.

Most modern NLEs that target the consumer DV25 market don’t really give you many professional audio options. You can’t choose which channels to take when you capture, instead you’re forced to take 1&2 as a stereo track. This is true in PPro even if you capture over SDI. The Vegas capture tool for SDI interfaces doesn’t seem to give you any audio options either.

I have to assume that the design is strictly DV25-centric, where channels 1&2 are embedded in the DV stream as a stereo track. If you capture DV, you have to take the audio too.

The solution is to use a thrid party capture tool like Scenalyzer.

Rob Mack