CODEWITHSUNDEEP
encodingmp3live-streamingicecast
Bulvak
Bulvak

Reputation: 1804

How can I monitor an mp3 live stream to detect corruption?

Once a month the mp3 streams messes up and the only way to tell it has messed up is by listening to it as it streams. Is there a script or program or tool I can use to monitor the live streams at a given url and send some kind of flag when it corrupts?

What happens is normally it plays a song for example or some music but once a month, every month, randomly, the stream corrupts and starts random chimpmunk like trash audio. Any ideas on this? I am just getting started at this with no idea at all.

Upvotes: 1

Views: 999

Answers (1)

Brad
Brad

Reputation: 163478

Typically, this will happen when you play a track of the wrong sample rate.

Most (all that I've seen) SHOUTcast/Icecast encoders (going straight from files) will compress for MP3 just fine, but assume a fixed sample rate of whatever they are configured for. Typically this will be 44.1kHz. If you drop in a 48kHz track, or a 22.05kHz track, they will play at different speeds while causing all sorts of random issues with the stream.

The problem is easy enough to verify. Simply create a file of a different sample rate and test it. I suspect you will reproduce the problem. If that is the case, to my knowledge there is no way to detect it, since your stream isn't actually corrupt... it just sounds incorrect. You will have to scan all of your files for sample rate. FFMPEG in a script should be able to help you with that.

Now, if the problem actually is a corrupt MP3 stream, then you have problems on your encoding side. I suspect simply swapping out whatever DLL or module you're using with a recent stable version of LAME will help.

To detect a corrupt MP3 stream, your encoder must be using CRC. If you enable it, you should be able to read through the headers of each frame to find the CRC, and then run it on the audio data. In the event you get an error (or several frames with errors), you can then trigger a warning.

You can find information on the MP3 stream header here:

http://www.mp3-tech.org/programmer/frame_header.html

Upvotes: 1

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