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Title: Detecting codec in a stream
Post by: stigc on 2012-10-07 12:46:16

How does e.g. VLC detects the codec when opening a http stream?

Both AAC and MP3 has a very short sync mark which often appears in other streams.

http://www.flickr.com/photos/52807817@N00/4423485655/ (http://www.flickr.com/photos/52807817@N00/4423485655/)
http://www.mp3-tech.org/programmer/frame_header.html (http://www.mp3-tech.org/programmer/frame_header.html)

Title: Detecting codec in a stream
Post by: stigc on 2012-10-07 13:07:08

I guess VLC parses the frame length number and sees if it matches the next sync mark?

Title: Detecting codec in a stream
Post by: benski on 2012-10-07 18:38:04

The first four bytes of an ADTS AAC frame header look exactly like an MPEG-1/2 "Layer 4" frame. So it's quite easy to detect the difference.

HydrogenAudio

Hydrogenaudio Forum => General Audio => Topic started by: stigc on 2012-10-07 12:46:16