Re: Serious Audio Response Flaw in Sony HVR-V1U - Submit Your Tests in Our Database
- From: "Mark & Mary Ann Weiss" <mweissX294@xxxxxxxxxxxxx>
- Date: Thu, 28 Jun 2007 08:59:42 GMT
appearance ofWell, the reality was starkly different from the hope that the
these connectors gave me.
You should not have been seduced by the "appearance" of professional
connectors normally associated with professional audio. These are
CAMERAS, not audio recorders, and even the $100,000.+ true hi-def
cameras have audio issues you need to be aware of. Your testing of the
camera was a good idea --- your initial assumptions is where you made
the first mistake.
You're correct, and this makes sense in the "traditional" sense that audio
for video has always been below mediocre. However, this is a digital audio
system on the V1U, not an analog linear tape head, like on the old VHS
shoulder-mount rigs, where low frequencies were limited by the iron core
flux saturation limit of the analog recording head on the linear track
audio.
With digital, there is no technical reason why the LINE level (as well as
the MIC level) inputs should not be flat from DC to where the Nyquist
sampling limit brickwall filter starts to roll off the upper end. To create
this rolloff of the low end, Sony would have to invest engineering and
component costs to deviate the ADC and op-amp response from their
normally-flat response. It is impossible to build a digital audio recording
system with low frequency sag, unless it was by intent.
AudioDevices.com tested the HDW-F900 and it is flat +/-0.1dB from 20-20KHz.
This indicates that Sony DOES know how to make CD-quality digital audio
circuits in their cameras.
I think Sony can pass off the V1U with this audio because video people
traditionally have become used to bad audio and don't expect much more from
the newer digital systems.
theNeedless to say, I think Sony has a major issue to correct with these
cameras. It's worse than the PD150 hiss problem. In all other respects,
V1U audio is acceptable. s/n is pretty good for a camera, but there's no
excuse to roll off the low end at 1222Hz.
There is something wrong with your camera - setup if things are rolled
off at 1222 hz.
That's what I thought--until I tested another V1U, brand-new from B&H. Same
exact curve. Line level, all wind and mic noise filters turned off moments
before the test, double-checked.
Last night, I tested a VX2000, prosumer model, with 1/8" mini jack and it
goes down two more octaves than the V1U. A prosumer camera with better bass
response than the pro camera. That really seems upside-down to me.
Even my $299 Zoom H4 is flat to 5Hz and
sounds way better than the audio on this camera.
The $299 Zoom H4 is an audio recorder --- not a camera. If Sony or
anyone else wanted to build high quality uncompressed PCM audio into
their cameras they certainly could.
Now this is a common misconception. PCM is not required to produce good
bass. In fact, my Zoom H4 records 64kbps MPEG when set to VBR MP3 mode and
it sounds better than the V1U audio and has window-rattling bass response.
If Sony can put a $20 ADC chip in their camera, then they can have DC to
Nyquist response from their audio. I suspect they neutered it by design,
possibly to define a market segment, but why they went this far overboard, I
don't know.
One thing you may not be aware of is the specifics of the HDV format
(which is essentially a fairly new hybrid format developed by JVC and
Sony). HDV uses very different methods to achieve a hi-def image
recording on standard DV tape. Also, to save bandwidth and keep the
files sizes manageable (one of the main goals for the HDV format) HDV
audio uses lossy compression (MPEG-1 Layer 2) to reduce the audio
bitrate to 384 kbit/s. DV audio uses uncompressed 16-bit PCM at 1536
kbit/s. As a result, HDV audio is technically inferior, although MPEG-1
at 384 kbit/s is regarded as 'perceptually lossless.' So, most of the
HDV format cameras can operate in the HDV mode (hi-def, sort of) or in
the standard def. DV mode. In DV mode, the camera audio will be
standard, linear 16-bit PCM audio and probably sound better than the
same camera shooting in HDV format.
This is a common misconcepton about MPEG audio. It's a DCT function that
separates audio into discreet bands, and looks at the harmonic overtones and
discards those higher frequencies that are below a threshold, where it is
determined that the majority of listeners won't notice the missing
overtones. There is no low frequency limit on MPEG audio. If there were,
then a billion MP3s wouldn't have any bass in them at all. As bitrate goes
down, it is the highs that suffer. Not the lows. It doesn't require a lot of
data to convey DC, or even low frequency AC. Data rate increases with
frequency, so it is the highs that need to be thrown away to fit the
datarate. And 320kbps is much better quality than the majority of MP3 files
floating around the internet.
At any rate, I tested my cameras in DV mode, to counteract this notion.
audioOne of the attractive features of the V1U is the promise of higher end
withthan the VX2000. Anyone seeing the attention Sony paid to XLR inputs
audioadjustable attenuators, individual AGC, etc., would conclude that the
better be pretty darned good.
Who made this promise? The attention paid to the XLR inputs is a start
in the right direction (we all know that the signal coming into the
camera should be as good as it can be, otherwise it makes no difference
how qualified the recording system is) but the use of MPEG-1 Layer 2
compression scheme compromises the audio. I think Sony, and probably
most camera people who think they can be a one man band, a total
filmmaker because they have the CAMERA, "would conclude that the
audio... be pretty damned good". For them, the audio is okay --- for a
professional sound engineer it probably still sucks.
It just goes with "reasonable expectation of audio that is congruent with
digital recording". Also, one generally expects that a $4800 camera with
phantom-powered XLR inputs would outperform a prosumer camera costing half
as much, with mini 1/8" passive jack.
thatIt's been almost 2 weeks since
they'd said they would contact me with their findings. I can only hope
they decide to recall the camera model and correct this glaring defect.
Hey, it's SONY. If it were just you and maybe 5 other people who bought
the camera, they might listen. They have sold way too many of them,
every minute of every day, to ever consider a recall. We're not talking
Firestone tires killing people on the road, we're just talking a
design/manufacturing decision by a giant corporation that resulted in a
compromised product (that is still selling like hot cakes).
Regards, Jeff Wexler
That's why I'm trying to educate people to expect digital audio quality (CD
quality) from a digital audio system on a modern camera. There's no
technical reason why this can't happen. CineAlta sports CD quality audio. I
think a $4800 camera with the attention Sony otherwise paid to the audio
menu and connectors should outperform a prosumer camera, and anything
digital should reasonably perform like the audio on the CineAlta. If we
awaken enough people in this industry, perhaps we can persuade Sony to
remove the high pass filter, or make it switchable. It affects both mic and
line inputs, which is bad if you need to take a house mix off a board. It
was pressure from owners that got the PD150 hiss problem acknowledged and
eventually corrected.
Best Regards,
Mark A. Weiss, P.E.
www.mwcomms.com
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