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Quick mp3 question

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Re: Quick mp3 question

Postby Hugh Robjohns » Mon Aug 05, 2019 3:22 pm

CS70 wrote:The difficulty with these things is that it's easy to overgeneralize - the devil is often in the the details (i.e. the context of usage).

Absolutely. Complaining about (or praising) MP3 is meaningless without also specifying the bit-rate (and to a lesser extent, the coding scheme) being used. The different coder designs aren't all equal either (see below), so you really should identify the specific coder being used, too.

High bit-rate MP3s are very hard to distinguish from the linear PCM source, by design. The proportion of people that can reliably detect artefacts is intentionally -- and demonstrably -- very, very small. The peer-reviewed research has been done and confirmed.

Conversely, low bit-rate MP3s tend to have more obvious artefacts that many will hear quite easily -- although a lot depends on the nature of the source material and how well it can mask the coding artefacts. A well-recorded talking book (single male speech) recording, for example, encoded at 128kbps may well sound perfectly acceptable and artefact-free, whereas a dynamic orchestral concerto at the same rate will probably sound pretty poor to many people.

Sure, the science is based on certain assumptions but these assumptions (and the corresponding algorithms) have been tested, verified and adapted several times over years before the format was finalized.

The really clever aspect to the MPEG codecs is that the specification only defines the way the replay decoder works. That intentionally leaves the door open to continual development of the encoders, so that as the understanding of the human auditory model improves, masking decisions determining which parts of the audio content are 'irrelevant information' and are therefore discarded, can be further optimised. All the encoder has to do is comply with the output data formatting expected by the receiving decoder. So different coder designers can make different decisions and prioritise different aspects in their algorithms.

And that's why certain people can hear stuff and other don't.

It's the familiar Gaussian or normal distribution model. The vast majority of people's hearing acuity sits in the middle of the curve. As you move out towards those with better or poorer hearing than 'average' their number rapidly diminishes, but there will always be some who are significantly better or worse than the 'average'. I don't know the exact percentiles for the different MP3 bit-rates but, it is designed to work for most people, most of the time... and it does that very well.

After many years of adoption, it seems that with a good encoder, a 256/320kps bitrate is definitely good enough, and 128kps holds water in many cases for most people, as theorized. No surprise most people don't complain!

I think that's a very good generalised summary. :-)
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Re: Quick mp3 question

Postby The Elf » Mon Aug 05, 2019 4:33 pm

I have no problem with lossy formats as end-destination, consumable formats, but anything that converts back from a lossy format to a lossless format should be made illegal! :tongue:

I know of one 'once mighty' CD recovered from MP3s that nearly made it back into mainstream production, but I won't name names... ;)
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Re: Quick mp3 question

Postby Hugh Robjohns » Mon Aug 05, 2019 5:46 pm

The Elf wrote:I have no problem with lossy formats as end-destination, consumable formats, but anything that converts back from a lossy format to a lossless format should be made illegal! :tongue:

Totally agree.

I spend the last few years of my BBC Training lecturer time trying to educate radio and TV production staff about why they should not use MP3s (and other lossy codecs) as source material... it was like hitting my head on a brick wall!

I kept getting the line: 'but it sounds alright on my phone and on the studio speakers, so it must be fine....'

They just couldn't or wouldn't grasp the idea that there are further lossy codecs in the transmission chain, so although it sounded okay in the studio, it becomes mangled to the real end-user at home or in the car if they're listing on DAB or DTT. :-( I could demonstrate the effects of codec concatenation, and they could all hear the results... but they refused to join the dots with their own practices!

Check out Steve Wright's afternoon show... he's forever playing lossy-codec audio clips grabbed off the internet. :headbang:
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Re: Quick mp3 question

Postby Mike Stranks » Mon Aug 05, 2019 7:47 pm

Hugh Robjohns wrote:Check out Steve Wright's afternoon show...

I'd rather not if it's all the same to you... teeth... edge...

And on the subject of horses for courses, I sometimes have to prepare spoken-word files for hosting on sites with very limited space available. As long as the source is good and clean I find I can generate MP3s at 16KHz, 32 kbps (Lame Encoder) and have them still sound perfectly acceptable for their intended use.
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Re: Quick mp3 question

Postby Tim Gillett » Mon Aug 05, 2019 8:45 pm

I occasionally do the same Mike, when I need to send demos to a customer or friend via email where here there's a 10 Mb size limit. It can be a fun challenge to pull every trick before encoding to make it sound as if it's not a low bitrate mp3. I think it was Mandy Parnell who said something like "that's real mastering", or at least what mastering used to be - making a lower fidelity delivery format still sound good.
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Re: Quick mp3 question

Postby Mike Stranks » Tue Aug 06, 2019 8:58 am

Tim Gillett wrote:I occasionally do the same Mike, when I need to send demos to a customer or friend via email where here there's a 10 Mb size limit. It can be a fun challenge to pull every trick before encoding to make it sound as if it's not a low bitrate mp3. I think it was Mandy Parnell who said something like "that's real mastering", or at least what mastering used to be - making a lower fidelity delivery format still sound good.

Not meaning to be patronising Tim, but you do know there are apps available where you can send fairly chunky data sets for free? (I don't mean Dropbox, Googeldrive et al...)

I've used several, but of late I've settled on WeSendIt https://www.wesendit.com/ as it's reliable, simple to use and, most importantly, easy for the recipients to access the sent files.

Just a thought...
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Re: Quick mp3 question

Postby Tim Gillett » Tue Aug 06, 2019 9:13 am

Not at all, Mike, thanks for the tip.
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Re: Quick mp3 question

Postby CS70 » Tue Aug 06, 2019 10:03 am

Mike Stranks wrote:
Tim Gillett wrote:I occasionally do the same Mike, when I need to send demos to a customer or friend via email where here there's a 10 Mb size limit. It can be a fun challenge to pull every trick before encoding to make it sound as if it's not a low bitrate mp3. I think it was Mandy Parnell who said something like "that's real mastering", or at least what mastering used to be - making a lower fidelity delivery format still sound good.

Not meaning to be patronising Tim, but you do know there are apps available where you can send fairly chunky data sets for free? (I don't mean Dropbox, Googeldrive et al...)

I've used several, but of late I've settled on WeSendIt https://www.wesendit.com/ as it's reliable, simple to use and, most importantly, easy for the recipients to access the sent files.

Just a thought...

As an incidental - it's funny that there are some unexpected cases where actually that doesn't work, for surprising reasons.

A couple years ago I did some video work for a middle-eastern singer, who wanted to send the finished product back to radio services in his home country. The video came out well and very high quality - but It turned out that the main communication system in his country is some sort of 3G or even Edge mobile network, so the video size had to be incredibly small to allow the majority of people to watch it.

I spent more time working the the coloring so that I could get it to the required size without it looking like lego blocks, than actually filming and mounting it.

We're lucky in our little worlds :)
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Re: Quick mp3 question

Postby blinddrew » Tue Aug 06, 2019 12:49 pm

CS70 wrote:I spent more time working the the coloring so that I could get it to the required size without it looking like lego blocks, than actually filming and mounting it.
Ugh. Tell me about it, restricted bandwidth is a major bane of my working life at the moment. You spend ages (well, a decent amount of time) getting a nice, clear, good sounding video, and then you have to compress the snot out of it to get it round the network and the colours go funny, the sound gets ugly, and everyone looks like they've been trying Trump's make-up cabinet. :(
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Re: Quick mp3 question

Postby CS70 » Tue Aug 06, 2019 1:26 pm

blinddrew wrote:
CS70 wrote:I spent more time working the the coloring so that I could get it to the required size without it looking like lego blocks, than actually filming and mounting it.
Ugh. Tell me about it, restricted bandwidth is a major bane of my working life at the moment. You spend ages (well, a decent amount of time) getting a nice, clear, good sounding video, and then you have to compress the snot out of it to get it round the network and the colours go funny, the sound gets ugly, and everyone looks like they've been trying Trump's make-up cabinet. :(

Make it black and white and it'll compress in a breeze! :D
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Re: Quick mp3 question

Postby Mike Stranks » Tue Aug 06, 2019 2:47 pm

With videos why not just put it on YouTube as 'unlisted'?

That's what I do. Only those with the specific link can access it and when everyone who needs to has seen it you just delete it.

Job's a good 'un!
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Re: Quick mp3 question

Postby blinddrew » Tue Aug 06, 2019 4:01 pm

Mike Stranks wrote:With videos why not just put it on YouTube as 'unlisted'?

That's what I do. Only those with the specific link can access it and when everyone who needs to has seen it you just delete it.

Job's a good 'un!
Because 1) accessing youtube is still using up our (very limited) bandwidth (in fact it adds an additional bottleneck in because all our branches route through our head office stack to get to the internet), and 2) that puts it outside our firewall and therefore we can't share any confidential information.
We do use youtube and vimeo for occasional things but in general we have to use an internal process to replicate files out overnight. Max file size of 80MB - even in B&W that looks pretty shoddy! :D
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Re: Quick mp3 question

Postby CS70 » Tue Aug 06, 2019 4:35 pm

Ahh yeah! Mine was supposed to be below 50Gb, basically a GIF would have done better!! :D
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Re: Quick mp3 question

Postby Mike Stranks » Thu Aug 08, 2019 10:01 am

blinddrew wrote:
Mike Stranks wrote:With videos why not just put it on YouTube as 'unlisted'?

That's what I do. Only those with the specific link can access it and when everyone who needs to has seen it you just delete it.

Job's a good 'un!
Because 1) accessing youtube is still using up our (very limited) bandwidth (in fact it adds an additional bottleneck in because all our branches route through our head office stack to get to the internet), and 2) that puts it outside our firewall and therefore we can't share any confidential information.
We do use youtube and vimeo for occasional things but in general we have to use an internal process to replicate files out overnight. Max file size of 80MB - even in B&W that looks pretty shoddy! :D

Fair enough...

Been there, done that, got the T-shirt. My work experience of such matters is now 10 years out of date. I'd anticipated that the world might have moved on... obviously not.
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Re: Quick mp3 question

Postby blinddrew » Thu Aug 08, 2019 11:28 am

Mike Stranks wrote:Been there, done that, got the T-shirt. My work experience of such matters is now 10 years out of date. I'd anticipated that the world might have moved on... obviously not.
A more than reasonable expectation. :)
In some matters we're very progressive, in some matters we're still 10 years behind where you were ten years ago! ;)
It was only in the last couple of years that we stopped having branches with dial-up connections... :o
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Re: Quick mp3 question

Postby gsc1ugs » Thu Aug 15, 2019 3:06 pm

Ok everyone who's interested, i got all my files in wav 1411kbps and boy can you tell the difference, have a couple questions, i cant edit properties to change title track names, if i import into audacity then export which at this point i cant edit this, will i loose the quality again?
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Re: Quick mp3 question

Postby The Elf » Thu Aug 15, 2019 4:19 pm

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Re: Quick mp3 question

Postby gsc1ugs » Thu Aug 15, 2019 5:13 pm

Great no need to reprocess wavs
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Re: Quick mp3 question

Postby ben howes » Fri Aug 16, 2019 1:05 pm

Codecs aside..
I'd recommend a dedicated player rather than a phone.
phone notification bleeps arriving over the PA is very naff. I've also experienced that syncopated rhythm of the cellular radio spilling out of the audio jack.
Aeroplane mode might help.
I also find the 3.5mm socket on many phones is not reliable from an electrical connection.
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Re: Quick mp3 question

Postby The Elf » Fri Aug 16, 2019 1:09 pm

ben howes wrote:I also find the 3.5mm socket on many phones is not reliable from an electrical connection.
If you even get one. Apple?!?!?!? :protest: :x :protest: :x
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