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Offline easyed

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file size hypothetical theoretical question
« on: April 14, 2015, 09:07:29 AM »
your thoughts please? hypothetical theoretical question:

same recorder, same bit depth, same sample rate, 4 recordings, all *EXACTLY* one minute long samples

-live loud rock and roll
-ambient sound in a normal room with no music or talking
-no input (not quite silence but instead the noise floor of the recorder)
-a sine wave

question is would the file size be the same on all four recordings?

my thinking is they'd all be the same file size, in fact, i'd posit that if you used a different recorder but the same bit depth, same sample rate and the same recording examples above the file sizes would be extremely close.  if i'm wrong help me understand why, please and thanks in advance!
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Offline opsopcopolis

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Re: file size hypothetical theoretical question
« Reply #1 on: April 14, 2015, 11:37:56 AM »
I believe it should be.  File size is not contingent on content, rather bit depth and sample rate.  Even if you use a higher bit depth/sample rate and record a lower quality sound your file still has that extra headroom whether it is being used or not
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Offline Gutbucket

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Re: file size hypothetical theoretical question
« Reply #2 on: April 14, 2015, 12:01:11 PM »
Non-data compressed (WAV) files will all be identical size, regardless of their actual content.  Doesn't mater if the content is recorded silence or all full-tilt clipping ear-bleeding overload.

The file size from different recorders may vary slightly, due to potentially different information recorded in the file header, but the audio portion of the WAV files from the different machines, running at the same recording rates for the exact same length of time, will be of identical size.

If data compressed, using either lossless or lossy compression, the file sizes will vary depending on the compression algorithm, the nature of the content and the similarity between channels.
« Last Edit: April 14, 2015, 12:03:16 PM by Gutbucket »
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stevetoney

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Re: file size hypothetical theoretical question
« Reply #3 on: April 14, 2015, 12:14:14 PM »
The file size from different recorders may vary slightly, due to potentially different information recorded in the file header, but the audio portion of the WAV files from the different machines, running at the same recording rates for the exact same length of time, will be of identical size.


If the clock speeds are slightly off on the two different recorders, that would alter the file size for the same duration of actual time since the number of samples would be different, no?  Over a minute, they'd still be very close, but not identical.
« Last Edit: April 14, 2015, 12:16:23 PM by tonedeaf »

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Re: file size hypothetical theoretical question
« Reply #4 on: April 14, 2015, 01:33:58 PM »
So no correlation in size of 2 flac recordings recorded with different gear and in this case size doesn't matter.   ;D

Offline easyed

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Re: file size hypothetical theoretical question
« Reply #5 on: April 14, 2015, 01:51:02 PM »
So no correlation in size of 2 flac recordings recorded with different gear and in this case size doesn't matter.   ;D

consensus?

if 2 recordings were of different length, different bit depth or different sampling rates we would not expect the file sizes to be the same.

a recording of the same length made of silence or loud rock with the same recorder, same bit depth, same sampling rate will both be the same file size.

file size is irrelevant to sound quality.  absolutely no bearing.

not like, for example, microphone choice, placement, recorder choice, or transfer lineage, all of which can have a huge impact on sound quality.  or, for example, the difference between internal mics from the lawn at Shoreline and high end external mics in the sweet spot into a nice preamp and a nice recorder.
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Re: file size hypothetical theoretical question
« Reply #6 on: April 14, 2015, 02:45:30 PM »
So no correlation in size of 2 flac recordings recorded with different gear and in this case size doesn't matter.   ;D

consensus?

if 2 recordings were of different length, different bit depth or different sampling rates we would not expect the file sizes to be the same.

a recording of the same length made of silence or loud rock with the same recorder, same bit depth, same sampling rate will both be the same file size.

file size is irrelevant to sound quality.  absolutely no bearing.

not like, for example, microphone choice, placement, recorder choice, or transfer lineage, all of which can have a huge impact on sound quality.  or, for example, the difference between internal mics from the lawn at Shoreline and high end external mics in the sweet spot into a nice preamp and a nice recorder.

True.  No different from the paradigm I deal with at work which is building Business Intelligence systems.  Often clients can't tie out their data because they load different inputs to 2 systems.  I often have to explain the only way they can tie out their two disparate systems with different data is clearing all the data since 0's always tie.  In other words, the file size will be the same before the recording starts 0 bytes.  Our "friend" Furburger will likely dispute this logic because he doesn't believe in science. 

Offline Gutbucket

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Re: file size hypothetical theoretical question
« Reply #7 on: April 14, 2015, 02:50:26 PM »
The file size from different recorders may vary slightly, due to potentially different information recorded in the file header, but the audio portion of the WAV files from the different machines, running at the same recording rates for the exact same length of time, will be of identical size.

If the clock speeds are slightly off on the two different recorders, that would alter the file size for the same duration of actual time since the number of samples would be different, no?  Over a minute, they'd still be very close, but not identical.

Yes, but that's covered by the "running at the same recording rates for the exact same length of time" part of the statement.  If the two clocks are not synced and are off slightly, then recording rates are not the same but slightly different, even if the machines are set to the same "nominal" sampling rate.  In other words, unless clock-synced both recorders aren't actually sampling at precisely 48kHz, although they will be very close to that rate.

if 2 recordings were of different length, different bit depth or different sampling rates we would not expect the file sizes to be the same.

a recording of the same length made of silence or loud rock with the same recorder, same bit depth, same sampling rate will both be the same file size.
^^
True.

Quote
file size is irrelevant to sound quality.  absolutely no bearing.

Not sure I follow this part.. If this is an extension of the the statement above it, then the file sizes should be identical.  In the real world case, two different files recorded on the same machine at the same rate and bit-depth will be have slightly different sizes if they were actually slightly different time durations. Similar to Tonedeaf's exception for two non-sync'd clocks, but in that case the time duration is presumed to be exactly the same, but the clocks are running at slightly different rates.
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Offline easyed

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Re: file size hypothetical theoretical question
« Reply #8 on: April 14, 2015, 06:26:05 PM »
The file size from different recorders may vary slightly, due to potentially different information recorded in the file header, but the audio portion of the WAV files from the different machines, running at the same recording rates for the exact same length of time, will be of identical size.

If the clock speeds are slightly off on the two different recorders, that would alter the file size for the same duration of actual time since the number of samples would be different, no?  Over a minute, they'd still be very close, but not identical.

Yes, but that's covered by the "running at the same recording rates for the exact same length of time" part of the statement.  If the two clocks are not synced and are off slightly, then recording rates are not the same but slightly different, even if the machines are set to the same "nominal" sampling rate.  In other words, unless clock-synced both recorders aren't actually sampling at precisely 48kHz, although they will be very close to that rate.

if 2 recordings were of different length, different bit depth or different sampling rates we would not expect the file sizes to be the same.

a recording of the same length made of silence or loud rock with the same recorder, same bit depth, same sampling rate will both be the same file size.
^^
True.

Quote
file size is irrelevant to sound quality.  absolutely no bearing.

Not sure I follow this part.. If this is an extension of the the statement above it, then the file sizes should be identical.  In the real world case, two different files recorded on the same machine at the same rate and bit-depth will be have slightly different sizes if they were actually slightly different time durations. Similar to Tonedeaf's exception for two non-sync'd clocks, but in that case the time duration is presumed to be exactly the same, but the clocks are running at slightly different rates.

the reason I mention quality, which of course is unrelated to file size, is that buttlicker's response to the posting of a better Fogerty recording than his was 'if it's better how comes is 80mb smaller?'
http://www.dimeadozen.org/torrents-details.php?id=524486&viewcomm=6821819#comm6821243
« Last Edit: April 14, 2015, 06:37:06 PM by easyed »
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Offline Gutbucket

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Re: file size hypothetical theoretical question
« Reply #9 on: April 14, 2015, 07:42:38 PM »
I don't currently have a Dime account so I can't see that linked page, however..

The simple answer in this case is that there is no direct correlation between files size and sound quality.  The files are slightly different sized empty containers which we can fill with whatever- good quality audio, crap audio, or with silence.  We can make a great sounding 16/44.1 WAV which smokes a 24/96 WAV, just by doing a better job of recording and putting much that better quality audio into that 3.5 times smaller container.  The good quality audio will fit within the smaller container easily.  The ultimate limits imposed by the bit depth and sample rate in this case is certainly not relevant (and is negligible in most cases).


But to address your actual question-
What exactly is 80MB smaller? the total file package?  Presumably these are FLAC data compressed files and the data compression will make the file sizes different, even if they are both 16bit/44.1kHz WAV files and happened to be exactly the same size uncompressed.  But the uncompressed WAVs are unlikely to be exactly the same size even if they are both 16/44.1 file sets, simply because the two file sets were tracked slightly differently by different folks, so each file and each entire set will not be exactly the same length.

In addition there could be extraneous data appended to the original WAVs, such as recorder manufacturer specific data.  For instance, file markers made on the R-44 fall into this category.   TLH removes that from the WAVs when FLAC compressing unless the Keep Foreign Metadata box is checked (I tell it not to strip that info when I compress my raw masters so I retain those markers in the FLAC'd but untracked master).

Beyond that, there could be different metadata in the two different FLAC sets, usually tagging info, but it could be anything, like photos.
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Offline Gene Poole

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Re: file size hypothetical theoretical question
« Reply #10 on: April 14, 2015, 07:47:53 PM »
the reason I mention quality, which of course is unrelated to file size, is that buttlicker's response to the posting of a better Fogerty recording than his was 'if it's better how comes is 80mb smaller?'
http://www.dimeadozen.org/torrents-details.php?id=524486&viewcomm=6821819#comm6821243

It's a meaningless assertion, but it could just be that the flac files were saved with a higher compression level.  Flac has 0-8 compression level settings.  the more compression, the more cpu needed to decompress, but not much of an issue on modern gear.

Offline jefflester

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Re: file size hypothetical theoretical question
« Reply #11 on: April 14, 2015, 08:04:03 PM »
The biggest likely contributor to FLAC file size difference (for same show/~same length within seconds) is whether the original WAVs are normalized, compressed at all, or with peaks under (or well under) 0 dB. A fileset with low levels will compress to smaller FLAC than a fileset that has been normalized/compressed somewhat to make overall louder.
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Offline Gutbucket

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Re: file size hypothetical theoretical question
« Reply #12 on: April 14, 2015, 09:19:25 PM »
I'm certainly no expert on the FLAC compression algorithm, but that makes sense.  Other audio attributes will also have an influence, such as how correlated the two channels are with each other (how similar or 'mono-ish', an X/Y recording will compress more than spaced omnis), and the nature of the sound itself (is it a recording of complex changing audio information, a simple and predictable sine wave, nothing but white noise, digital silence, or whatever, just to list some extremes).  Normalization making a large difference mentions makes sense because all the data space above peaking is entirely empty can be discarded.  By contrast the noise at the bottom is not empty and cannot be thrown discarded entirely.
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Offline dabbler

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Re: file size hypothetical theoretical question
« Reply #13 on: April 15, 2015, 04:37:56 AM »
FLAC definitely compresses quieter files smaller.

Find any unnormalized file and try encoding FLAC with sox, with and without normalization:

   # This command will normalize to -0.1 dBFS and encode to FLAC
   # the "stats" output will confirm the levels
   sox original.wav max.flac gain -n -0.1

   # Straight up encoding to FLAC only, again the "stats" output will just
   # confirm levels are unchanged.
   sox original.wav original.flac stats

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Re: file size hypothetical theoretical question
« Reply #14 on: April 15, 2015, 08:27:31 AM »
Furburger is too stupid to understand this.

"a "lossless" recording that is SMALLER.


man, you're rich, and I'm not talking in money or brain cells."


 

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