The_Lhc said:
That's what it says.
Like you mentioned in post 18 - the actual dynamic range of real music doesn't get anywhere near the 96dB potential maximum that CD quality 16/44 offers.
That's what it says.
Like you mentioned in post 18 - the actual dynamic range of real music doesn't get anywhere near the 96dB potential maximum that CD quality 16/44 offers.
In its most simple terms an MP3 algorithm removes information that you can't hear anyway. It removes the very quiet noises that were inaudible already because they were masked by much louder noises that were occurring at the same time. It doesn't reduce the volume of the loud noises it just removes the quiet ones.
Yesterday I did a quick experiment. I converted a few lossless WAV files to MP3 using the LAME encoder then compared them using the 'Dynamic Range Meter' which is a free add-on that can be installed into the Foobar music player software (you can try it yourself it's not complicated). With every song that I tried, the dynamic range rating was always the same on both the WAV and MP3 versions. In all cases the peak dynamic range was always a perfect match to within 0.02dB at the very most, and in a few cases the MP3 occasionally even had 0.01dB more dynamic range than the original WAV file.
A 0.02dB difference is well below what is audible.
Yesterday I did a quick experiment. I converted a few lossless WAV files to MP3 using the LAME encoder then compared them using the 'Dynamic Range Meter' which is a free add-on that can be installed into the Foobar music player software (you can try it yourself it's not complicated). With every song that I tried, the dynamic range rating was always the same on both the WAV and MP3 versions. In all cases the peak dynamic range was always a perfect match to within 0.02dB at the very most, and in a few cases the MP3 occasionally even had 0.01dB more dynamic range than the original WAV file.
A 0.02dB difference is well below what is audible.
For what it's worth when I asked Ashley James how dynamic range is measured this was his reply:
"Dynamic range is not calculated, it's an arbitrary process applied to the individual preference of sound engineers who may be overruled by Record Companies and Mastering engineers. They believe extra treble and bass and lots of compression helps sell music by making it appear louder and more exciting. Over the years more and more has been applied in a competition to be the loudest and it has ruined lots of otherwise quite good music.
Compression has alwas been used because records have a very limited dynamic range (30dB after a few plays), but when CD came along and you could have the full dynamc range of analogue tape (65dB) and digital (96dB) all sorts of uncompressed recordings appeared such as thunderstorms and canons from Telarc, Garage Doors from hi fi news and drums from Joan Armatrading and these caused lots of problems. Most amplifiers were nowhere near powerful enough and they clipped nastily, so there was a backlash and now much music has had the life compressed out of it. Some compromise is needed.
For the record MP3, AAC, Ogg Vorbis and more are actually not compressed at all. That term was applied by scurrilous audiophile retailers to discredit an excellent system that improved the sound of music if it did anything. Lower bitrate MP3s sound slightly softer and less harsh.
Perceptual Encoding as it's called is a process by which music is divided up into narrow frequency bands and the least loud stuff, what scientific experiments say you can't hear, is discarded. Variable Bit Rate as used by Apple is a process that increased the bit rate to encode a bit of music than might otherwise not sound exactly the same as the original.
Perceptual Encoding has been a godsend and it works brilliantly, which is why everyone (almost) uses it even if they have the best headphones.
"
"Dynamic range is not calculated, it's an arbitrary process applied to the individual preference of sound engineers who may be overruled by Record Companies and Mastering engineers. They believe extra treble and bass and lots of compression helps sell music by making it appear louder and more exciting. Over the years more and more has been applied in a competition to be the loudest and it has ruined lots of otherwise quite good music.
Compression has alwas been used because records have a very limited dynamic range (30dB after a few plays), but when CD came along and you could have the full dynamc range of analogue tape (65dB) and digital (96dB) all sorts of uncompressed recordings appeared such as thunderstorms and canons from Telarc, Garage Doors from hi fi news and drums from Joan Armatrading and these caused lots of problems. Most amplifiers were nowhere near powerful enough and they clipped nastily, so there was a backlash and now much music has had the life compressed out of it. Some compromise is needed.
For the record MP3, AAC, Ogg Vorbis and more are actually not compressed at all. That term was applied by scurrilous audiophile retailers to discredit an excellent system that improved the sound of music if it did anything. Lower bitrate MP3s sound slightly softer and less harsh.
Perceptual Encoding as it's called is a process by which music is divided up into narrow frequency bands and the least loud stuff, what scientific experiments say you can't hear, is discarded. Variable Bit Rate as used by Apple is a process that increased the bit rate to encode a bit of music than might otherwise not sound exactly the same as the original.
Perceptual Encoding has been a godsend and it works brilliantly, which is why everyone (almost) uses it even if they have the best headphones.
"BigH
Well-known member
I think foobar does use difference between peak and RMS, this may show you: dr.loudness-war.info/album/view/74103
matt49
Well-known member
The_Lhc
Well-known member
matt49 said:
Especially in the last paragraph where he's going on about bit compression and not dynamic range compression, which is where we came in I believe...
matt49 said:
To be fair that was my mistake. When asking the question I used the word 'calculated' instead of 'measured' which changed the meaning of the question somewhat.
The example shown above actually shows the MP3 as having more DR than the original WAV version. With the majority of tracks it was usually the WAV that had slightly more DR than the MP3. But that's irrelevant because in all cases (with a 320kbps MP3) they were always matched to within 0.02dB which is far less than what's audiable.
Most of the comparisons were done using 320kbps MP3's. But even with ultra low bit-rate MP3's (I tried as low as 45-85kbps VBR) the dynamic range was still always matched to within 0.06dB.
Most of the comparisons were done using 320kbps MP3's. But even with ultra low bit-rate MP3's (I tried as low as 45-85kbps VBR) the dynamic range was still always matched to within 0.06dB.
matt49
Well-known member
steve_1979 said:
Steve, you're being fair minded to a fault, but I don't see why "calculated" is any different from "measured" in this context. You seem to have asked how dynamic range is calculated/measured; it's a question about the methodology of calculating/measuring DR. His answer, as you've reproduced it, is about how compression is used. On this evidence, he's simply misunderstood you, for whatever reason (and I can imagine a couple).
steve_1979 said:
The DR figure on foobar is NOT the same type of measurement as the 96dB dynamic range figure quoted for 16bit CDs and is NOT comperable.
Dynamic range as an engineering measure is the ratio of the loudest reproducable sound to the quietest. For a digital linear PCM system that is the ratio of full scale (2^16) to 1, that is 96dB.
Foobar is trying to come up with a measure of the audible compression in a track. The best info I could find on the web indicates it is the dB difference between the peak level of the track and the average RMS level of the track (although the screen grabs above indicate otherwise). This may well be a good measure of audible compression, but has nothing to do with the engineering measurement of dynamic range of the track itself.
Arguably, even a highly compressed track could use a significant portion of the 96dB available on a CD. A very quiet run in to the start of the music, then the rest of the track compressed and at a very high level would generate a high dynamic range result using the accepted measure of dynamic range. I guess the foobar approach tries to come up with a measure averaged over the track that replicates the real world listening experience.
No problem with that, but that is an 'index of compression' (or whatever they want to call it), it isn't 'dynamic range' in the engineering sense.
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