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Old October 29th, 2005, 08:31 PM   #1
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Fostex MR-8HD

Has anyone used the Fostex MR-8HD 4-track recorder? I am considering it for simultaneous 4 channel recording auxillary to my video camcorder, than mixing the audio in post-production. Anyone have experience with this unit?
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Old October 30th, 2005, 08:14 AM   #2
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FWIW, don't have any direct experience but something I noticed you might keep in mind is that it only records in the CD sampling frequency of 44.1 kHz. This will require resampling in post in order to more easily maintain synch with the in-camera audio which is recorded at 48kHz. Not a major glitch but it could be an issue. You might want to find a recorder that will record at a 48kHz sampling rate.
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Old October 31st, 2005, 10:49 PM   #3
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Fostex

Thanks Steve for the feedback. The 44.1k to 48k conversion is not really such a problem and at least it is a known quantity.

What attracted me to the Fostex is the 4 channel simultaneous recording, the convenient inputs (XLR, 1/4"), the high capacity hard drive which allows lossless recording (not compressed) for a two hour performance and the digital output to my computer through a USB port. And, most importantly, it is $400. If I could get all these features for a comparable price but with 48k sampling I would. I do not need long battery life since I will be in a theatre recording stage performances with power available and a sound booth providing the music (from CD) channels and ambient (from two microphones) tracks.
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Old November 1st, 2005, 05:17 AM   #4
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Quote:
Originally Posted by Allen Twarowski
Thanks Steve for the feedback. The 44.1k to 48k conversion is not really such a problem and at least it is a known quantity.

... .
It could become an issue, at least one should be prepared to deal with it if it does. A couple of general cautions... Resampling upwards from 44.1 to 48 is more of a problem than resampling downwards such as recording at 96 and resampling to 48. When recording at one rate and resampling to another, you get best results when the two rates are even-integer exact multiples of each other. (That's why the sample rate options of 48, 96, and 192, or of 44.1 and 88.2 are often offered in pro gear.) But 48 is not an integer multiple of 44.1 and so the software has to interpolate between samples from the source material, essentially guessing at the missing information, and that can introduce distortion and noise. Second, not all NLE's will resample when importing audio. If your's doesn't or if you neglect to tell it to, when you play the audio it will play at the faster project sample rate and the 44k samples will finish in 0.91875 seconds, signifigantly less than the 1 full second that they should take. That amounts to the audio playing faster than the video by almost 2.6 frames every second and if your audio is supposed to be lip-sync dialogue, you'll lose sync to picture very quickly.
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Old November 3rd, 2005, 01:16 PM   #5
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When I said that the sample rate conversion was not such a problem, I didn't mean to simply ignore it. You are correct that that would be a big mistake. Since I am recording a ballet that goes on for about 45 minutes per act, synchronization of audio and video could be off by minutes - even without the high visibility of spoken dialogue, this large of a synchronization problem would be readily and painfully noticeable.

I meant the conversion can be done with any number of software programs, Cooledit (now Adobe Audition) is probably one of the best for high quality conversion. I am sure the analog to digital conversion when the sound is originally captured will introduce a lot more noise than the subsequent resampling. The final product is a DVD with the audio dolby compressed so audio is further degraded in quality. However, I agree with you that it would be much nicer if the Fostex unit sampled at 48kHz.
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Old November 3rd, 2005, 01:57 PM   #6
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Quote:
Originally Posted by Allen Twarowski
When I said that the sample rate conversion was not such a problem, I didn't mean to simply ignore it. You are correct that that would be a big mistake. Since I am recording a ballet that goes on for about 45 minutes per act, synchronization of audio and video could be off by minutes - even without the high visibility of spoken dialogue, this large of a synchronization problem would be readily and painfully noticeable.

I meant the conversion can be done with any number of software programs, Cooledit (now Adobe Audition) is probably one of the best for high quality conversion. I am sure the analog to digital conversion when the sound is originally captured will introduce a lot more noise than the subsequent resampling. The final product is a DVD with the audio dolby compressed so audio is further degraded in quality. However, I agree with you that it would be much nicer if the Fostex unit sampled at 48kHz.
Yep, you're right on all points...
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