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Old November 5th, 2011, 10:34 AM   #1
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PCM or AC3?

Looking for best quality sound. Currently have a SONY SR12 with PCM 16 bit sound, but mic input is broken. (I run a Gefell mic into a JuicedLink and then into the cam). Most new cameras under $2000 seem to come with Dolby AC3, which I think is compressed, but not sure. Is AC3 as good quality as PCM 16? Was considering Canon xa10 but it has AC3.
Thanks for any info.
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Old November 5th, 2011, 01:26 PM   #2
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Re: PCM or AC3?

Compressed is always inferior to uncompressed. Granted, SOMEtimes it doesn't make enough difference to matter. But it is never good practice to record compressed data where it will be going through subsequent post-production steps.
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Old November 5th, 2011, 02:02 PM   #3
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Re: PCM or AC3?

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Originally Posted by Richard Crowley View Post
Compressed is always inferior to uncompressed. Granted, SOMEtimes it doesn't make enough difference to matter...
One approach - compressed is OK for dialog, but use a separate uncompressed recorder when shooting music. YMMV.

Is there a current prosumer AVCHD cam that doesn't compress audio?
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Old November 5th, 2011, 02:21 PM   #4
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Re: PCM or AC3?

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Originally Posted by Seth Bloombaum View Post
One approach - compressed is OK for dialog, but use a separate uncompressed recorder when shooting music. YMMV.
It is SOMEtimes adequate for dialog. But I would never select any compressed scheme when uncompressed is available. It is false economy. Of course, it depends on how important sound is to your production.

Quote:
Is there a current prosumer AVCHD cam that doesn't compress audio?
"Some professional models allow recording uncompressed linear PCM audio."
AVCHD - Wikipedia, the free encyclopedia

Recording compressed audio in camera is fine if you are making home movies. But if you are doing anything requiring post-production, you are starting out behind the curve. Sure you can make compromises anywhere, but best to know what are the consequences to allow yourself to make a better informed decision.

I am assuming that by "compressed" we are all talking about LOSSY compression. Because, of course, LOSSLESS compression is not a factor at all.
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Old November 5th, 2011, 02:22 PM   #5
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Re: PCM or AC3?

Ac160 uses pcm
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Old November 5th, 2011, 06:34 PM   #6
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Re: PCM or AC3?

We haven't had uncompressed audio recording generally available on camcorders since DV cameras. HDV - compressed. Most AVCHD - compressed.

While it is true that "uncompressed is always better quality", saying so is not particularly helpful, IMHO. We constantly must deal with realities of money, workflows, and resources, and figure out what quality is good enough for our work, or for a particular project. Producers and shooters have had to figure out what HDV audio (compressed) is good for; most people hear it as good enough for dialog. It's a reasonable approach, certainly not right for everyone or every project. Me, I'm not so familiar with the many choices of the newer generations of AVCHD cams, but, the Canon XA10 that the OP mentions is a $2000 cam, about the least expensive that gives you both a straightforward workflow without syncing separate recordings and the many advantages of XLR audio inputs.

I'm glad to see the Panny AC160 Josh mentions above; there is absolutely a need for camcorders with uncompressed audio recording. It's $4500.

I suppose I'm a little touchy on this subject, because I've heard similar appeals for "quality at any cost" way too many times. That's not an approach a working pro who expects to make money can afford. It would indeed be "better" if we were all shooting uncompressed video and recording 24-bit uncompressed audio, supported by full grip and lighting and production staff all the time. But, you gotta' make a decision at some point - will the people watching perceive a meaningful difference, and, will I still be able to make money if I do it that way?

So, yeah, as a general practice, I think (well) compressed audio is fine for dialog, and I've done as much as 48-ch uncompressed 24-bit audio for video for music projects.
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Old November 5th, 2011, 08:57 PM   #7
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Re: PCM or AC3?

Thanks for the replies. Sound quality is as important to me as video quality since most of what I record is music -- live concerts, solo guitar, or small groups. I find it odd that the SONY SR12 from a couple of years ago, which does not even reach "prosumer" level, offers PCM 16 bit sound, but the latest and greatest cams do not, unless you are willing to shell out for $3000 or up. I understand that an external recorder can be used and then you combine the audio with the video in post, but I is very nice not to have to bother with that step. I recently attended a music convention and recorded 30 tunes by one artist. Avoiding the step of combining and syncing 30 times is no small matter. Also, it is more cables, another battery, more things to break and go wrong. Maybe it is worth it to shell out the $300 plus dollars to repair the SR-12?
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Old November 6th, 2011, 12:04 AM   #8
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Re: PCM or AC3?

To be fair, isn't music generally recorded with higher quality gear than the "crappy electronics" in camera audio circuitry? I've heard sound guys complain about the quality of cams like the Varicam and F900 of yore, so our little prosumer babies must be really craptastic in that department.

I realize you may not have those options open to you, but if you deal almost exclusively in music recording, is it maybe worth it to look into 24 bit recording options?
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Old November 7th, 2011, 04:23 AM   #9
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Re: PCM or AC3?

Quote:
Originally Posted by Seth Bloombaum View Post
...
I suppose I'm a little touchy on this subject, because I've heard similar appeals for "quality at any cost" way too many times. That's not an approach a working pro who expects to make money can afford. ....
I have to disagree. The State of the Art sets the bar and the working pro needs to be able to bring both the proper tools and the proper skills to bear so as to achieve it at will. There's always downwards pressures on price by the same people who try to convince you "ice milk" tastes just as good as ultra-premium ice cream but the people who actually make the majority of the money in any profession are those who refuse to compromise the quality of the product they deliver. Would you hire a surgeon who took the attitude "ahh, that'll be good enough for the fee the patient can afford to pay?" As Debbie Fields once said, "Good enough, never is!"
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Old November 7th, 2011, 06:08 AM   #10
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Re: PCM or AC3?

I've been looking into the ac160 and 130, and asked around about how bad that AC130 is. Audio guys tell me if everything is record well/ideally, it's not bad at all. It's when having to bring up low levels that I'll start to have issues. Can't quite remember what they said about processing (EQ, compression, etc.) in regards to how it would hold up.
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Old November 7th, 2011, 01:35 PM   #11
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Re: PCM or AC3?

PCM 16 at 44.1khz is the format on CDs, this takes up approximately 10mbytes per stereo minute. all tho that isn't much by today's standard it is still considerably bigger than most compressed formats and chews up more bandwidth than the manufacturers like, as they need it for their video processing.
the standard for non-compressed video audio is PCM 16 at 48khz which is even a bit bigger than that.

on another note. most cameras at best have OK audio circuits, and good professional recorders and mixers far exceed the quality of camera's on-board audio. but on the more pro end they can be quite acceptable even in lower quality it might be ok if recorded with attention. one of the reasons for external mixers is to raise the level higher so the camera doesn't have to raise its own noise floor up and the gain is performed by a much cleaner audio circuit of the mixer.

if you are delivering to a post house then you want to deliver PCM over AC3, let them create the AC3 mix.

hope that helps and doesn't cloud the issue
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Old November 7th, 2011, 08:41 PM   #12
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Re: PCM or AC3?

Quote:
Originally Posted by Steve House View Post
I have to disagree. The State of the Art sets the bar and the working pro needs to be able to bring both the proper tools and the proper skills to bear so as to achieve it at will. There's always downwards pressures on price... Would you hire a surgeon who took the attitude "ahh, that'll be good enough for the fee the patient can afford to pay?"
With all respect, if the people at home can't hear a difference, and it doesn't pencil out, then it isn't pro. "Pro standards?" A professional is someone who earns their living doing the work. That's the primary definition.

There are certainly times when a certain standard is, well, standard in a market or industry. But even then, many of them exist for reasons of market positioning more than a genuine need for standardization. Take AVID in the broadcast market, for example, or better yet, ProTools. Some people will tell you that if you're not cutting in AVID or recording/mixing/sweetening in PT, your work's no good, you're not professional. What a load of c##p. Did you know that Mac is the creative platform, and PCs are for accounting and email? Same thing.

Equipment investments have to pencil out in a way that a pro can make their money back and perhaps even make a profit before it's obsolete.

As I wrote above, when it matters, it matters. When I'm recording music, if I don't have what's needed I rent. Same for picture, for that matter. I've got 24 channels of video clocked 24/48 uncompressed audio recording, and have rented to up the count to 48-ch. when needed.

But to say that quality is always needed for dialog? Don't think so. But, if you can make it work for your bottom line, and still provide competitive pricing in your market, more power to you.

Back to the original poster, he was looking at a $2000 solution for a cam, wondering about audio quality. I have a student with that cam (Canon XA10), he's happy with it, I've heard a couple projects shot with it, dialog is fine. I've not heard a music recording. Later, we learned that the OP does need something that works for music, but we don't know what market he's going to, we don't know what sort of standards he needs to meet. Broadcast is different than YouTube, for sound as well as picture.

"State of the Art?" There isn't one. There are many. It's market dependent.

BTW, we aren't surgeons, nobody is going to die on our table, pros are just trying to do good work and get paid for it.

The pro needs to understand value. Value to client. Value in a market. Where that particular bar is. How to reach it.
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Old November 7th, 2011, 10:53 PM   #13
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Re: PCM or AC3?

Thanks for all the comments. I am looking to record CD quality audio (not for youtube). The venues I record in do not lend themselves to mic stands, cables, recorders, etc, and I do this on my own. The set up I use now bypasses the cam's poor quality mic and preamp. I'm using a good quality mic (~ $1000 Gefell) run into an outboard JuicedLink preamp, then into the camera at uncompressed 16 bit. On playback, the unedited audio, over Dynaudio studio monitors, sounds great. Really great. And I don't have to combine every audio track with video in post. Think run & gun with best quality audio.

The problem is that consumer cam mic input jacks are poorly made, just soldered to a circuit board, so they break easily. Repair costs are very high, probably 40% of the value of the cam (used value). Unfortunately it does not seem that PCM audio is available on consumer cams anymore (if you know of any, let me know). So either I go the separate audio and combine in post (a hassle), or shell out for a Canon xf100, or similar. Maybe the SONY SR12 was an oddity with PCM, and I should put the money into repair?
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Old November 8th, 2011, 09:55 AM   #14
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Re: PCM or AC3?

I do not consider the acquisition audio format to be that big an issue when recording audio to direct to camera. It's the camera's mic pre-amps that are usually crap. A good quality mixer or pre-amp will usually yield a good sounding track. (providing one has the audio recording skills to begin with)
In post, never destructively edit a compressed data format audio file, transcode the original file to PCM if that's going to be the case. The final mix can then be rendered to the desired format with minimal quality loss.
Of course for those who record 16 bit at very conservative levels, that could be a problem.. even w/ PCM.
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