Hi all.

I have a question regarding using laptops to play back mp3's.

I have read in other places about the importance of a good quality sound card for play back purposes, which, in a way, makes sense.

However, the question I have is does it really matter ?

If you are putting the output of a laptop through your mixer (and thus, cross overs and eq's etc), does it make that much (if any) difference ?

I would be interested to read your thoughts on this..........





Thanks,

Glenn.

I don't have direct experience of this but logic suggests a poor quality signal (e.g. from a not very good soundcard) is a poor quality signal, whatever you do with it.

In basic terms..
Audio in .wav files take less processing power compared to un-compressing an .MP3 file because compressed files need to be un-compressed in order to play!
Therefore the CPU will need to work harder playing MP3's than say .wav files.

Temperatures can rise playing uncompressed media, therefore system problems could potentially occur.
If a system (laptop) has a dedicated sound card with onboard memory, issues or problems are less likely to occur as the sound card is doing work / assisting. The sound should be marginally better than a standard motherboard soundcard too.

I'm sure there are those who can explain better....

I use the numark djio because it gives me two output channels so that i can still use my external mixer, and also i find the outputed sound is better quality than what i could achieve by connecting to the headphone output on my internal soundcard.
and at only £89 it quickly pays for itself!

I have an external Creative Soundblaster Connect. I can tell that it sounds *much* better than the internal sound card on the laptop (more so on the previous laptop)...

If you have a poor signal to start off with it isn't going to sound any better when processed by your mixer / amp / etc.

I didn't know that but it begs a question about media players that accept SD cards. Some of the newer ones combine this functionality with a front mounted USB port but none will play .wav files, only mp3.

Bearing in mind the former take less processing power than the latter that seems surprising and I'm assuming it's firmware-related..

Any thoughts?

Storage requirements would be too large.


I think I may have incorrectly explained myself on my earlier post.

Componants on a dedicated sound card should be somewhat better than the sound card on the system motherboard. A dedicated sound card may not actually do any file de-compressing, but an external card should indeed sound better.

Mainly storage, and possibly speed of SD Card interface. In theory, its just firmware restriction, but the main reason will be capacity.

SDHC Cards can get fairly large capacity, but normal SD Cards are limited to 2GB, you won't get many ~50MB songs in a 2GB Card - probably only 2 CD's...
SDHC will go to 32GB, and when using 320Kbps MP3's will hold 1000's of tracks, but if using WAV files, its still not much storage.

If the SD interface is using the "easy" SPI based method, then throughput will be fairly slow, and the data throughput may not be high enough for uncompressed WAV files (@ 160KB/Second)


Decoding a WAV file is pretty simple (from a software viewpoint), and is patent free.
MP3 is much more difficult, and requires more processing power, and they will have pay patent fees for producing a hardware player.

I don't understand the storage point since the current crop of these machines allows USB connection of hard or pen drives as well as SD cards (normal and high capacity). I think you're saying that .wav files would be slower to process, which is why these players are limited to .mp3 files. Is that correct?

Pretty much. WAV files have a data rate of 160KB/Sec, whereas a typical 320Kbps MP3 is much lower at ~41KB/Sec
I would expect any bottleneck to be in the USB or SD interface, and there is other overhead with reading these files in (FAT File management) which would put demands on the processor.

Bear in mind that the processors used in these devices will have low processing power, and the demands in I/O needed to stream in a 40MB WAV file compared to 10MB MP3 File will be higher.

If the Player allows mixing, the the overhead will be double - 320KB/Sec for 2 Wav files. This doesn't sound much for our 2GHz+ PC's, but for a low end micro controller, with possibly no multi-tasking OS this would be difficult.


I code embedded software for the day job. The current project will require either SD Card and/or USB interface and this is leading us down the path of a major processor upgrade with an embedded OS (possibly embedded linux) to ease interfacing.
Privately, I'm hoping the final design could turn into my own private MP3 player

At home i have noticed a difference in sound quialty between my onboard sound card and my djio, however at a typical gig with the music blasting, the crowd noise and room acoustics i have tried it and seen no noticable difference.

I use the DJIO for the multiple output facility.

NB I see some of the sd media players are limited to 4gb cards
http://www.djanddiscostuff.com/prodpage.asp?prodid=2684

There are a few standard 4GB SD cards available - however not all standard SD readers support them properly. The unit in that link doesn't support SDHC so hence why only supports up to 4Gb..

If you want some bed time reading on SD (if you can't sleep!)..

http://en.wikipedia.org/wiki/Secure_Digital_card

cheers

David

Thanks for that, i studied computer science/electronics 20 years ago and was well into what was what and how things worked but have not worked in the industry and have switched off regarding technology these days. Gone are the days of the old tape player plugged into a spectrum eh.

So i see why a sd card player is half the price of a usb device. A usefull tool as a back up unit but wouldnt like to use one as primary playback device.

Back to topic - Sticking with laptop vdj and djio and considering second laptop for backup

Thanks for the input everyone. It makes more sense now.

So, a sound card with it's own memory is a good option - can anyone suggest a few and, is the one that Mcelec mentions one of these type.

Thanks,

Glenn.

http://www.numark.com/djio#
There is a fair ammount of spec available on there.
My system spec is as follows and to date i have had no problems whatsoever.
Acer 5620
Intel Core 2 duo T5450
120gb hdd
1gb ddr2 ram
Windows XP pro
Virtual DJ pro 6.0.2
Numark DJio

Not the most up to date machine but it works for me. Things may be different with vista / windows 7 and i would recommend you ask for furthur info.