MP3s: why do some play in my car and some not?

[Dr Huge Longjohns]

My new Skoda has a USB socket through which to play music from a flash drive. So I copied a whole load of songs onto a USB drive from my Mac, mostly mp4 but quite a few mp3. But most of the mp3s won't play, the system says file type not supported. Some play however and by a bit of detective work it seems that the ones that play are ones where the cover art has copied over to the USB drive. Does this mean that these MP3s are different to the ones that the cover art hasn't copied over or is this just coincidence. All MP4s seem to play absolutely fine. I'm perplexed!

[Hugh Robjohns]

I'd be surprised if the cover art was the problem. The ones with the cover art are probably mp3s of 16/44.1 standard source audio.

So perhaps there's an issue with the other files having different sample rates (96k?) or word lengths (24bit?). Or maybe recorded in a VBR mode instead of CBR... Or even located in a sub-directories that make then unreachable to the player.

I'm sure a little detective work on the file properties will identify the differences between playable and unplayable files.

[Folderol]

VBR is my first suspect actually - a surprising number of players can't handle them

MY Skoda also has a USB port but I've never bothered to try it - I'm too used to just plugging my ancient iRiver H320 in to the 3.5mm jack socket

[The Elf]

Yep, I've also had cars that refused to play VBR. These days I just stream everything from home on my phone and play that through the car stereo - all problems solved.

[Dr Huge Longjohns]

I'm still doing my detective work, nothing obvious jumps out, different bit rates doesn't seem to be the issue and they're all 44.1 sample rate. How do you find out if they're CBR or VBR, this info doesn't seem to appear in the iTunes info? But it seems really odd that the ones where the art has copied to the USB drive seem to be the ones that play. Why wouldn't all the artwork copy over from iTunes???

[Dr Huge Longjohns]

Found out about VBR v CBR and the vast majority of the files that won't play are regular CBR it seems, all 128, 256, 320 etc.

[Folderol]

Found out about VBR v CBR and the vast majority of the files that won't play are regular CBR it seems, all 128, 256, 320 etc.

Well that's a first

[FrankF]

Yep, I've also had cars that refused to play VBR.

I think you'll find that Philip K. Dick predicted that many years ago.

[Martin Walker]

Yep, I've also had cars that refused to play VBR.

I think you'll find that Philip K. Dick predicted that many years ago.

As he did many other things

Martin

[Stratman57]

I to have a Skoda (4x4 Yeti), and I found that when I tried to play MP3s from an SD card, there was a limit to the number of subdirectories it could access. One I got rid of these it would play all of the files.

Regards, Simon.

[Dr Huge Longjohns]

Nope, good thought but it's not that either, the files that play and won't play are in the same top level folder.

[Dr Huge Longjohns]

On a related note, anybody tried the bluetooth transmitters that plug into your iPod?

[CS70]

Can be a number of things - most likely a property of your car stereo, rather then the files.
Some have a max file limit - they can't play any files beyond the say 1024th, which will appear as random "unplayable" when the songs are ordered in anything else than the order they were phisically copied. Some support only FAT32. Some can't cope with ID3 tags (or ID3v2 or v3 etc) and get confused. Some have problems with different encoding paddings. Files with DRM protection. The player firmware creating a cache file on the disk listing files that are there (and then failing to update it). The list goes on (and for long!).

The fact you mention album art suggests an issue with ID3 tags - which is fairly common on hardware players. Try and take a song which doesn't play, strip all the ID3 tags and see if it does. Change the USB stick label. Look for hidden files in the USB stick you have.Take note of a file that doesnt play, put it on a new USB stick and try with that - if it works, it's likely caching issues.

Short of getting the logs directly from the hardware unit, it's difficult to say what of the myriad issues can be, so the only procedure is to try a lot of stuff until you hit what's what.

[Dr Huge Longjohns]

That's all really helpful, thanks CS70!

[Hugh Robjohns]

Actually... good point about DRM protection. Are some of your files protected downloads?

[Dr Huge Longjohns]

Solved! While researching on Google I found a random post about windows v mac on MP3s saying that you should always drag mp3 files from one place to another on macs rather than copy.

I had been loading the files onto the USB stick by dragging to copy from the iTunes file library but discovered that if I drag the file from the main iTunes APP window instead the artwork got copied too (if it has artwork) and, hey presto, these files now play in the car. I have no idea why this is or why some MP3s work fine copying in the previous manner, however. I'm sure one of you chaps will explain what's going on!

[Folderol]

Sheesh
You had just one job Apple. Even Microsoft got it right!

Mods, we need a 'DOH' smiley

[The Elf]

I long ago abandoned iTunes for the utter bloated nonsense it is. I use CloudBeats for all my audio playback.

Now I can play audio from any of my cloud storage services, and from my NAS, no matter where I am. I can download files *if I choose to*, or just stream - and I can play any format I've yet to come across - no need for any conversion. No copying, no connecting to iPhone to transfer files...

Evermusic is another good one.

Nope, I'd say ditch iTunes - your life will become simpler!

[CS70]

What is iTunes?

[Folderol]

What is iTunes?

iForget

[CS70]

What is iTunes?

iForget

iKnow

[The Elf]

What is iTunes?

iForget

iKnow

iCarumba!

[Drew Stephenson]

ineverceasetobeamazedbythewaythesethreadscanwander

[muzines]

I had been loading the files onto the USB stick by dragging to copy from the iTunes file library but discovered that if I drag the file from the main iTunes APP window instead the artwork got copied too (if it has artwork) and, hey presto, these files now play in the car.

I can't speak for your library, or what versions of software of how your mp3 files were sourced, but as a test, I dragged a random file from the iTunes library in finder, and also did the same from the iTunes interface, and the files were verified byte identical.

I did it with a few mp3s and m4as, same results.

As for some people saying "you shouldn't copy an mp3 file, you should drag on a Mac" - well, it just makes me think of the kind of hokum that people that don't know any better spout as a general rule because one time some weird problem they were having worked when they did it one way, without understanding what was going on, and which was very likely a pebcac issue anyway...

[Dr Huge Longjohns]

As I'm digging deeper into this I've discovered it's not just MP3s it's some MP4s too. Here's a grab showing two files on the USB drive.

The second was dragged from the iTunes folder via Finder on my old mac running High Sierra, the first is from the iTunes interface just now on the new mac running Catalina. As you can see, one includes the artwork, the other doesn't (I've changed the name of the original one as the folder would allow me to keep both.) The one with the artwork plays, the other doesn't.

And here's a grab showing the info for each file. As you can see the one without the artwork has all its info missing so somehow this has not been copied across in the original move, or is invisible, as it's still showing as the same size file exactly.

So there you go, most odd.