What does audio file format error means

Yes it's usual with some mobile phone .... they cant support some file format... may be the file you are transferring from laptop to mobile is not supported by mobile.

It's possible that the file type of the music file(s) you are trying to listen to are not a supported format of your mp3 player. Your player only supports MP3 and WMA audio formats. You should check the music files you are tying to play to confirm they are of a compatible format.

http://www.cobyusa.com/files/manuals/MP300_MN.pdf

1. Check whether the file format of the audio file you are trying to play in the Walkman is supported by the Walkman.
You can check the supported file formats in the manual of the Walkman under "Specifications".

2. Check whether the issue occurs with all the audio files. If you are not able to play the file which you were able to play in past, then it must be the issue with the Walkman.

Then you may reset the Walkman to check whether the issue is resolved.
Press the RESET button located at the bottom of the Walkman to reset it.
You may also try Formatting (USE FORMAT OPTION IN WALKMAN) the Walkman and re-transfer the audio files to the Walkman to check whether the issue is resolved.
NOTE: Never format the Walkman in the Computer as it will delete all the Supporting files in the memory of the Walkman.

You may also try transferring the audio files using the supplied Software like Content Transfer, WMP 11 and SonicStage.

well.. might b bcoz of virus.. jus do a hard reset and format ur card again n now fill ur stuff.. ( if u've mentioned ur mob model means it'll would be easyier to answer n i would've given u d reset codes.......) any how, for nokia *#7370# s d general reset code.....

If it is a certain file, or a group of files, i would delete all audio from the media player, and read the system handbook, to see all compatible files, and buy a converter to convert them the the right file format. some converters are AVI, which I would recommend. When i bought it, it was around $20. Most likely you Mp3 plays (besides MP3 format) a windows media player format, since Windows Media Player even has a sync button to download songs quickly to your audio device. If your files were in the right format, then they might have been corrupted, or invalid, meaning they had information missing, or they werent correct with the codes. So I would just re-load them.

The only format that your player supports is as follows: MP3, WMA, ATRAC3, and ATRAC3plus. So if you try to transfer an audio file that is not in one of these formats then you will get an error. Look at the properties of the file you are transferring and verify that it is one of those file types mentioned above. If it is then make sure that the bit-rate of the files is not too high...some players do not play the very high bit-rate audio files or some variable bit-rate files.

Assuming you mean a USB flash drive or MP3 player via USB, I first have to warn you that you must obey all copyright laws for copyrighted songs. That being said, as long as you have purchased a song legally, you can put that on any device you wish. It's not easy because all of the software out there restricts you to explicitly NOT be able to use the song on any device you want even though you own the right to listen to it now.

It is easiest to burn the files to CD first, then import them into iTunes as MP3 then copy the MP3 files from your iTunes folder in My Documents\My Music\iTunes to your USB device.

Most USB devices use the file name to identify the song so you will need to rename the MP3 files on your USB device.

Maybe you have transferred a song of unknown format. I would reset the device and start over.

well the first question i would ask is how you are transfering music and video to the ipod. The reason i ask is because it sounds like you are not using itunes. itunes is the only way to actually put content on any ipod. with all that said when using itunes connect the ipod witht he provided cable and push the restore button on the summary screen for the ipod which should appear in itunes when you plug in the ipod to the computer you are using. after it restores you can try adding music and a video and see what happens

The songs are perhaps in the wrong format.  This player will not accept copy-protected iTunes (AAC) files.  Also, the license on your files may not permit transfer to mp3 players. Definitely check the bitrates on your files, b/c this Sony can only accept certain ranges of bit rate.
This is my general spiel about music formats, but note that your Sony does accept DRM-protected files with transfer rights, so not everything in the following blurb applies fully to you: All of these problems occur because the user is trying to download a song format that the player does not recognize. Every music file is in a certain format. The most common music file formats are Mp3, WMA, AAC (iTunes), WAV, RA, etc.  In addition, every file format type is in a certain bitrate, size, etc.  By far the most common issue is that the music file contains a license or copyright (especially with WMA or AAC file formats).  Each Mp3 player only recognizes a certain number of these formats. Every Mp3 Player is different. You will have to check your Mp3 player’s product specifications (specs) or user’s manual to find out which formats your particular Mp3 player recognizes. When you try to download or sync the wrong file format, you will get one of the errors that I mentioned above.   If you want to know what file type you have, then you must find the location of the individual music file on your computer, right click the title of the song, and select the option “Properties” from the menu.
Mp3 player product documentation is not straightforward.  If a player supports only non-protected WMA files, it will merely say that it supports WMA – it will not tell which type of WMA it supports.  A player that supports DRM-protected WMA’s will usually indicate such on the box (usually with a Windows Plays For Sure logo – which is actually an ironic misnomer).  DRM stands for Digital Rights Management, and it is a type of licensing system for WMA files.  It is used extensively by mp3 player music services such as Bearshare, LeapFrog, Napster, and others.  Not all DRM licenses are created equal – there are licenses with “play rights,” burn rights,” and “transfer rights.”  Play rights mean that you can only play the song on your PC – it will play fine on your computer, but it will not play in your mp3 player even though it appears to transfer.  Burn rights mean that the song can be burned to CD.  Transfer rights mean that the song can be transferred onto an mp3 player that supports DRM-protected files.  Then, there are unlimited licenses and limited licenses.  Limited licenses only allow you to play a song for a certain length of time. You would have to pay extra to continue using the song after that trial period is over – the time length ranges from a few days to several months or longer.
-Tha Mp3 Doctor