Posted by Mark & Mary Ann Weiss on 06/26/07 19:37

> > The results are abysmal. The camera fails on frequency response. It
> > gets a
> > "very poor" rating.
>
> Video cameras have never been noted for their great audio
> performance (from the perspective of audio production
> professionals). No offense to the video people. I started out
> doing audio,but got involved in video because of the notoriously
> poor audio I was hearing in video producions.

I know. However, today, in 2007, with the advent of cheap, high quality
DACs, there is no excuse not to have a flat response to DC. Even when a
cheap hand held digital recorder can rival some studio equipment, I would
expect at least better frequency response on a Sony "Broadcast" camera than
I get from most consumer camcorders.


> But your example is bad even by video camera "standards".
> To be fair, the frequency response curve you posted rather
> highlights the remarkable LF rolloff. "They" typically use a
> much longer X-axis and a much "compressed" Y-axis to
> give the impression of a broader and flatter bandpass. It
> doesn't change the data, but makes it look more palatable.

Well you have to realize that RightMark is designed that way because rarely
do digital systems deviate more than +/-0.1dB across 20-20KHz. So in order
to measure these fine differences, the scale is magnified vertically. But
this also illustrates just how absurdly bad Sony's digital audio circuitry
is.


> Jay Rose, an audio post-produciton mixer in Boston has
> written a couple of (good, IMHO) books on audio for
> digital video. He also contributes regularly to video
> publications. One of my favorite articles is one he and
> his son wrote on actual measurements of DV cameras a
> couple of years ago. It is availble online here...
>
http://www.dv.com/features/features_item.php?category=Archive&articleId=2390
2929
> IIRC, none of them were as bad as your measurements.

Of course, because none of the DV cams have this bad a low frequency
rolloff. And he only measured noise and distortion, not frequency response.
Why? I have measured earlier DV and analog cameras and none were this poor
on the low frequency side. I can understand a shoulder-mounted VHS camcorder
with analog audio heads having a roll off below 100Hz, because there's not
enough iron in the head to produce consistent flux below 100Hz, but on a
digital system, the ONLY limitation is set by Nyquist--the sampling
frequency, which limited the UPPER cuttoff, not the lower.
I am continuing to add additional cameras to the database. Apparently there
is almost a complete blackout of information on video camera audio to date.


> My prime camera is a Sony DSR-300 which has a remarkable
> video performance (particularly in the low ambient light
> situations I often shoot under). And the audio is reasonable,
> (for a video camera). I have even made casual, documentary
> CD releases from audio recorded on the DSR-300. But even
> it has only passable audio performance when compared
> against real professional audio equipment.

Yes, these earlier models produced passable audio to 100Hz. But Sony seems
to have devolved the audio quality on the newer cameras, except CineAlta,
which is flat +/-0.1dB 20-20KHz. Go figure.


> It might be worth a call/email to Jay to see if he is hearing/
> seeing this same kind of problem with the stuff he gets in to
> mix that was shot on the new generation of HDV cameras,
> etc.

That's a good idea. I'll see if I can get contact info from the publisher.


> You might also want to ask this question over in the
> production sound newsgroup...
> news:rec.arts.movies.production.sound

Will do. Thanks!


> It is interesting to note that on Sony's web page with specs
> for the camera, the video is favorably compared to 35mm
> film, etc. But note the complete lack of ANY specifications
> for audio (except connector types and impedances). Others
> have noted this in the past (the concentration on video
> performance, with audio appearing to be an afterthought).
>
http://bssc.sel.sony.com/BroadcastandBusiness/minisites/HDV1080/HVR-V1U/spec
..html

Yes, and at first, I thought the reason they didn't specify audio was
because it is digital, and doesn't suffer the vagaries of analog, therefore,
it's de-facto CD quality. NOT! Now I understand why they avoid specifying
it.


> As long as people buy those things for their picture quality,
> Sony, et.al. have no motivation to make anything better
> than "telephonic" audio quality, and the double-system
> sound professionals (over on r.a.m.p.s) will still have need
> of their separate audio recorders. Alas, just another
> example of "devolution" and entropy in the universe.

Well it goes with the whole MP3 mentality of the public. In an age when we
are able to hear the benefits of 24/96 digital audio over CDs, the world has
taken a huge step backwards to MP3. And when you look at HDTV broadcasts in
the big box stores, and all I see are a lot of macroblocks and a picture so
artifacted that I cannot understand how broadcasters allow this to go over
the air, then I see things in a completely different context: the audio
doesn't matter to the public, especially if they'll watch HDTV with tons of
macroblocks covering the screen.

I got a response from Sony today, flatly denying the problem, stating that
their testing is an industry standard and "The results these tests have
yielded show the V1U's performance to be comparable to that of the DSR-PD170
and within Sony's specification for the HVR-V1U" That last part bothers me,
because Sony won't state what their specification for the V1U is. I sense
more of Sony's obliqueness on this matter. It's going to take a lot more
pressure from us to get them to acknowledge the problem. They've offered to
test my camera and return if free of charge. But since I have two, and both
measure this poorly, I would have to conclude that there is nothing about
either that doesn't meet Sony's mysterious specifications.





Take care,



Mark & Mary Ann Weiss



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