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Quick mp3 question

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Quick mp3 question

Postby gsc1ugs » Sat Aug 03, 2019 9:57 am

Would the play back quality from an iphone be any different to a dedicated mp3 player or ipad?
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Re: Quick mp3 question

Postby Hugh Robjohns » Sat Aug 03, 2019 10:03 am

No.

But I'd advise against using MP3s for live amplified performances if you can.

The science behind the lossy-coding used in mp3 was based on normal listening levels. When played back louder in live situations all the assumptions the codec made about the masking behaviour of hearing fail, and so coding artefacts become a lot more obvious and distracting. The louder the playback, the more obvious they become.

So, ideally, use original WAVs or a lossless coding like FLAC or ALAC, or if you have to use mp3s, use the highest possible bit rate (320kbps).

And avoid concatenating lossy-codecs -- which means chaining one after the other -- as this creates even more artefacts! So avoid sending mp3 files over bluetooth to a wireless speaker, for example!

But all mp3 players do the same thing, so it matters not whether you're using an iphone or an ipad or a dedicated mp3 player or whatever.

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Re: Quick mp3 question

Postby gsc1ugs » Sat Aug 03, 2019 10:47 am

So i should hear the diff with the same song in wav and mp3 format?
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Re: Quick mp3 question

Postby Dave B » Sat Aug 03, 2019 11:09 am

Yes
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Re: Quick mp3 question

Postby Martin Walker » Sat Aug 03, 2019 2:38 pm

One easy way to pick out MP3 artefacts is to just listen to the Side signal, using a freeware plug-in like the Brainworx bx_solo from Plugin Alliance:

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Re: Quick mp3 question

Postby gsc1ugs » Sat Aug 03, 2019 2:47 pm

Whats a side signal?
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Re: Quick mp3 question

Postby ef37a » Sat Aug 03, 2019 2:58 pm

gsc1ugs wrote:Whats a side signal?

Good question!

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Re: Quick mp3 question

Postby hobbyist » Sat Aug 03, 2019 3:05 pm

gsc1ugs wrote:So i should hear the diff with the same song in wav and mp3 format?

Absolutely, uUnless you are deaf from listening at SPL that is over 85.
How anyone can listen to mp3 and like it is a mystery.

The difference between mp3 and wav is extreme and I am not a golden eared snob. mp3 makes my ears hurt.

OTOH I do not have 10000usd speakers and gold plated litz wire or any of that extreme stuff stereophile magazine says is absolutely necessary for good sound.
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Re: Quick mp3 question

Postby Hugh Robjohns » Sat Aug 03, 2019 3:06 pm

gsc1ugs wrote:Whats a side signal?

Its the 'stereo difference' signal, (left minus right*), or if you convert the left/right stereo into a Mid-Side equivalent, it's the Side signal -- as Martin referred to it.

This is why I'm forever berating the manufacturers of monitor controllers who fail to provide the facility -- it's an extremely useful and informative feature for assessing the signal quality, stereo alignment, imaging, and more besides...

* the stereo difference signal is more usually created by inverting the polarity of the right signal and adding it to the left (or the other way around), so (left plus minus-right).

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Re: Quick mp3 question

Postby ef37a » Sat Aug 03, 2019 3:39 pm

Oh! The difference signal! Hafler and all that swaddlin'.

Messed with that years ago when the Quadraphonics war was in full flow.

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Re: Quick mp3 question

Postby forumuser918214 » Sat Aug 03, 2019 4:32 pm

I would like to see double blind listening test results that show that mp3 at 256 or more bitrate is distinguishable from the unencoded musical source. As far as I know, there is none. There was a lot of careful listening done during development of the codecs. It was not just development based on assumption. This is over the course of years of actual blind listening tests. Where are published results to back up your claim?
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Re: Quick mp3 question

Postby gsc1ugs » Sat Aug 03, 2019 4:42 pm

Trouble is, downloaded pre done backing tracks are mp3, I can convert mine to wav but is that pointless at this point if they have been firstly created as exported mp3?
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Re: Quick mp3 question

Postby hobbyist » Sat Aug 03, 2019 4:49 pm

gsc1ugs wrote:Would the play back quality from an iphone be any different to a dedicated mp3 player or ipad?

Both bad. Just bad differently.

mp3 is horrible. use wav.

phones are inferior to speakers or other transducer_systems but may not make mp3 worse.
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Re: Quick mp3 question

Postby hobbyist » Sat Aug 03, 2019 4:55 pm

forumuser918214 wrote:I would like to see double blind listening test results that show that mp3 at 256 or more bitrate is distinguishable from the unencoded musical source. As far as I know, there is none. There was a lot of careful listening done during development of the codecs. It was not just development based on assumption. This is over the course of years of actual blind listening tests. Where are published results to back up your claim?

I thought I saw results from AES many many years ago on topics like this, doing ABCX double blind tests. Some were in a side show type test, not in their main papers but the results were still made available.

I recall they saying that some folks could identify when they used 192 and 384 rates and said they sounded better. That was A/D/A not mp3 specifically though.

But I have to think there are results for mp3 testing out there too.

Storage is cheap now. There is no need to compress to save memory or disk space like the old days.
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Re: Quick mp3 question

Postby Eddy Deegan » Sat Aug 03, 2019 4:56 pm

gsc1ugs wrote:I can convert mine to wav but is that pointless at this point if they have been firstly created as exported mp3?

Yeah, if the source is an MP3 there is little point converting it to WAV as the WAV will just accurately reproduce the artifacts present in the MP3 playback.

High bitrate MP3s are not that bad for domestic listening at a pinch, and certainly good enough for background music in the home but to my ears are often noticeably inferior to CD / WAV on anything other than bad speakers.

This difference becomes more evident the louder the listening volume so I would avoid using them for live purposes wherever possible.
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Re: Quick mp3 question

Postby gsc1ugs » Sat Aug 03, 2019 5:59 pm

So if i can get WAV files, which one do i use

signed 16bit
signed 24bit
or
32bit float and what may i also ask is the difference? would i hear this bit rate higher
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Re: Quick mp3 question

Postby blinddrew » Sat Aug 03, 2019 6:13 pm

16bit will be fine, it more than covers the dynamic range required! :)

24bit is good for recording (to give yourself plenty of headroom), 32bit is for behind-the-scenes maths in DAWs.
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Re: Quick mp3 question

Postby James Perrett » Sat Aug 03, 2019 6:17 pm

In an ideal world you might want to go for 24 bit files but 16 bits will usually be fine.
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Re: Quick mp3 question

Postby gsc1ugs » Sat Aug 03, 2019 6:19 pm

Thnaks for the advice, now the hard work, changing them all - :headbang:
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Re: Quick mp3 question

Postby Eddy Deegan » Sat Aug 03, 2019 6:26 pm

gsc1ugs wrote:Thnaks for the advice, now the hard work, changing them all - :headbang:

Just to be clear, in case it wasn't. You were correct when you said that converting MP3s to WAVs was pointless, so when you say 'changing them all' I hope you're referring to generating WAVs from original masters (or getting the original audio in WAV format) and not comverting MP3s to WAVs!
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