Mixpre/SD 302 + Zaxcom ZFR100 with Stereo Adapter at DVinfo.net

Martin Saxer · March 27th, 2007, 01:49 PM

... has anybody already had a chance to test this setting?

Martin

Bill Brock · July 2nd, 2009, 06:57 AM

I'm about to...sorry its two years after your post!

Bill Brock · July 2nd, 2009, 07:04 AM

I actually am going to pick up the stereo adapter for the zfr100 today and will connect it to my sd302. I spoke with zaxcom and it seems their .zax files compress 24-bit 48khz down to about 400kbps using a proprietary algorithm, then their software gives you the final format you need. Now the limitations are the compression cuts out anything above 17khz on the spectrum, and in stereo mode it still only gives you max bandwidth of about 400kbps. So roughly 200kbps per channel. So some bits are definitely lost, but they said for dialog there won't be any issue with sound quality...they were more concerned that the minisd may not be as reliable for a primary recorder. So its up to the individuals judgement if those limitations relegate it to a backup recorder vs. other options. When I get a chance, I'll post some sound samples in stereo mode and mono mode if anyone is interested?

Brooks Harrington · July 2nd, 2009, 11:27 AM

I'm interested!

Brooks Harrington · July 2nd, 2009, 07:07 PM

How did you find out the data rate?
I assume the ZAX files are some kind of high quality MP3 with a variable bit rate, because the Zaxconvert software uses LAME encoder.
When I asked Zaxcom about the files the ZFR100 makes, all I got was "it's a secret!"

Bill Brock · July 6th, 2009, 12:38 AM

Well, they say 12 hours on 2GB memory right...so just back calculated a rough rate then asked them what kind of compression rate and such and they were nice enough to correct my slightly wrong answer saying it was closer to 400 kbps and was a proprietary format. Well honestly its most likely based off of some standard since developing a compression algorithm from scratch for a small company is a pretty big undertaking. Then asked about if the 400kbps was for each channel and he told me it was shared...so mono gets twice the bits and I could see in the spectrum that anything above 17khz was gone so I knew my mic was full range, and the zfr was full range...so what was causing the cutoff of 17khz and above...must be the compression...so that's probably why he spilled the beans.

Anyway, starting to do some rough tests so I'll post some when I have a few. Not sure I can still do mono mode using the sta100 but I'll try and see what happens.

March 27th, 2007, 01:49 PM	#1
Martin Saxer Regular Crew Join Date: Feb 2007 Location: Oxford, UK (until 2008: Lhasa, Tibetan Autonomous Region) Posts: 65	Mixpre/SD 302 + Zaxcom ZFR100 with Stereo Adapter ... has anybody already had a chance to test this setting? Martin

July 2nd, 2009, 06:57 AM	#2
Bill Brock Regular Crew Join Date: Mar 2008 Location: Dallas, TX Posts: 26	I'm about to...sorry its two years after your post!

July 2nd, 2009, 07:04 AM	#3
Bill Brock Regular Crew Join Date: Mar 2008 Location: Dallas, TX Posts: 26	I actually am going to pick up the stereo adapter for the zfr100 today and will connect it to my sd302. I spoke with zaxcom and it seems their .zax files compress 24-bit 48khz down to about 400kbps using a proprietary algorithm, then their software gives you the final format you need. Now the limitations are the compression cuts out anything above 17khz on the spectrum, and in stereo mode it still only gives you max bandwidth of about 400kbps. So roughly 200kbps per channel. So some bits are definitely lost, but they said for dialog there won't be any issue with sound quality...they were more concerned that the minisd may not be as reliable for a primary recorder. So its up to the individuals judgement if those limitations relegate it to a backup recorder vs. other options. When I get a chance, I'll post some sound samples in stereo mode and mono mode if anyone is interested?

July 2nd, 2009, 11:27 AM	#4
Brooks Harrington Regular Crew Join Date: May 2007 Location: Pasadena, CA Posts: 152	I'm interested!

July 2nd, 2009, 07:07 PM	#5
Brooks Harrington Regular Crew Join Date: May 2007 Location: Pasadena, CA Posts: 152	How did you find out the data rate? I assume the ZAX files are some kind of high quality MP3 with a variable bit rate, because the Zaxconvert software uses LAME encoder. When I asked Zaxcom about the files the ZFR100 makes, all I got was "it's a secret!"

July 6th, 2009, 12:38 AM	#6
Bill Brock Regular Crew Join Date: Mar 2008 Location: Dallas, TX Posts: 26	Well, they say 12 hours on 2GB memory right...so just back calculated a rough rate then asked them what kind of compression rate and such and they were nice enough to correct my slightly wrong answer saying it was closer to 400 kbps and was a proprietary format. Well honestly its most likely based off of some standard since developing a compression algorithm from scratch for a small company is a pretty big undertaking. Then asked about if the 400kbps was for each channel and he told me it was shared...so mono gets twice the bits and I could see in the spectrum that anything above 17khz was gone so I knew my mic was full range, and the zfr was full range...so what was causing the cutoff of 17khz and above...must be the compression...so that's probably why he spilled the beans. Anyway, starting to do some rough tests so I'll post some when I have a few. Not sure I can still do mono mode using the sta100 but I'll try and see what happens.