5 replies to this topic

[abcsound]

Hi,
i would like to know if someone knows how the audio-video sincronization for winamp or mediaplayer works.
Because it probably reads some parameters from the audio file but which?

Any ideas?

thank you!

[Alexander]

I am very uncertain of what you are asking, are you referring to how a video file has a container of both video and audio, and they synchronize as they play?

Generally the audio file should be the same length as the video file, however each specific video container has its own format to introduce audio in to specific portions.

http://en.wikipedia....format_(digital)

[abcsound]

Hi,
thank you for you reply!

What i was saying is... Media Player for example has an integrated engine of video synthesis that goes together with audio, every audio that i play.
So it probably reads the amplitude change of the audio file or the frequency change of the audio in order to be sincronized with the audio that i'm playing. (for example http://windowsmania....ia Player11.jpg)

So i'm interested in to extract these values from an audio file and have a text file where is written for example that :
-0.10 change some
-0.15 change some other

The problem is not what to change, but how to know that at 0.10 there is something important that happens (probably a great amplitude or frequency change) and how to read it from a wave or mp3 file.

I hope all is more comprensible now.

Thank you a lot.

[Alexander]

Ah yes, this would normally be referred to as a "Visualization".

Your audio formats are encodings of raw audio samples, and would really just be piles of data, i.e.
https://ccrma.stanfo...cts/WaveFormat/

You would need to use a programming library of which can read audio files (there are many out there) to access the actual information the encoding provides, I am unaware of any off hand that would dump raw information.

You are correct that the visuals would be based off the frequency or modulation/amplitude, as those spikes would provide feedback to the changes in the audio as a visual output.

[abcsound]

Thank you!
now i can read DATA from wav now i must see how to threat these numbers, probably is the difference between these values that gives me what i want

[Alexander]

abcsound said:

Thank you!
now i can read DATA from wav now i must see how to threat these numbers, probably is the difference between these values that gives me what i want

The data is likely completely random in terms of the audio encoding it contains, you likely will not get anything useful over static sound.