Embedded Flash MP3 player slow on some files, normal on others

Question

I am using a embeddable Flash based MP3 player (The standalone Version of Wordpress Audio Player, to be exact) to play audio on the web page of a client. Given the nature of Flash based players - AFAIK they all use Flash's audio/video decoding libraries - the exact player product might not matter, though.

She complains that some specific audio files sometimes tend to play slowly, as if on a tape deck that doesn't run at full speed. Her machine is a 5 year old Sony Vaio with a 1.5 GhZ Pentium M Processor, so it's not top of the line anymore but it should not have trouble decoding anything, let alone a MP3 audio stream.

I can't verify the problem because we can't set up an audio connection (slow Internet on a remote island), nor can I reproduce it on my 3.3 GhZ dual-code Workstation, but this is a person whose error reports have seldom turned out unfounded in the past, so I tend to take them seriously.

I see differences between the encodings of the MP3 files (see below).

My question: Has anybody ever experienced something like this? If yes, what was the reason? If it's something in the encoding (which I suspect), could somebody give me pointers towards which setting(s) to change?

This is what Winamp tells me about a file that is sometimes slow:

MPEG-1 Layer 3
128 Kbit, approx. 966 frames
48000Hz Stereo

CRC: Yes, Copyright: No

This is what Winamp tells me about a file that is never slow:

Encoder delay: 576, Zero Padding: 1584
MPEG-1 Layer 3
151 Kbit (VBR), 12405 Frames
44100Hz Joint Stereo

CRC: No, Copyright: No

Answer 1

This is likely because the sample rate info in the header file does not match the sample rate the file was encoded with. Try fixing the problematic file with one of the MP# fixer utilities: google search.

It is also possible that this is a driver issue on their pc, and reinstalling/updating their audio driver may solve the problem.

Answer 2

I think this is a bug with certain versions of the Flash player. I have a Flash-based MP3 audio player that I made with the same problem. The solution is to make sure it is a 44,100 kHz MP3 file... or make your users upgrade their player.

Here is my site with the details: http://www.quickmediasolutions.com/sandbox/audio_player/