Linking internet documents with compressed audio files
A method for embedding a non-audio file into a compressed audio file is disclosed. The disclosed method is capable of decoding and constructing previously encoded audio files with embedded non-audio information. The method of the present invention also includes steps for embedding the non-audio information at the proper time within the compressed audio file, wherein the decoded non-audio information can link to an Internet document for viewing during playback of the decoded audio source.
1. A method for encoding non-audio information with a compressed audio stream, comprising the steps of:
(1) receiving a compressed audio stream;
(2) selecting non-audio data to embed in said audio stream;
(3) identifying at least one modifiable block within said audio stream, said modifiable block having an audio sample that exceeds an audio quality threshold value; and
(4) modifying a portion of said modifiable block in said compressed audio stream to encode therein at least a corresponding portion of said non-audio data at a selected point in the audio stream such that said portion of said non-audio data is reproducible by a decoder at a selected time interval along with the audio within said compressed audio stream.
2. The method of claim 1 , wherein said compressed audio stream is an MP3 compliant stream.
3. The method of claim 1 , wherein said non-audio data is a document file.
4. The method of claim 1 , wherein said non-audio data is an Internet address.
5. The method of claim 1 , wherein timing information is embedded along with said non-audio data and said timing information determines said selected point in the audio stream.
6. A method for encoding non-audio information into a compressed audio file, comprising the steps of:
(a) Getting a subset of non-audio data to embed;
(b) Reading a block of audio data samples,
(c) Determining whether the maximum value of said audio sample in said block exceeds a threshold value below which the embedding of data would unacceptably degrade the audio quality for a user;
(d) Repeating step (b) if said threshold is not exceeded;
(e) Modifying the least significant bits of a subset of said block, wherein a digital representation of said non-audio information is encoded;
(f) Determining whether the maximum of said modified block exceeds said threshold;
(g) If said threshold is not exceeded then adding a small amount to the audio sample with maximum value;
(h) Continuing with step (a).
7. A method for decoding embedded non-audio information from an encoded digital audio file, comprising the steps of:
(a) Reading a block of encoded audio data samples;
(b) Determining whether the maximum value of said encoded audio sample in said block exceeds a threshold value wherein a maximum value below said threshold indicates that no non-audio information was embedded;
(c) Repeating step (a) if said threshold is not exceeded;
(d) Reading the least significant bits of a subset of said encoded block, wherein a digital data code is decoded;
(e) Determining whether the decoded digital data code represents a valid non-audio information; wherein said valid non-audio information is found in an expected set;
(f) Repeating step (a) if said decoded digital data character code is not in said expected set;
(g) Adding said decoded valid non-audio information as the new non-audio information.
8. The method of claim 7 , comprising step (i) wherein said decoded non-audio information is displayed to a user.
9. The method of claim 8 , comprising step (j) wherein said decoder links said user to an Internet document determined by a URL formed by said decoded non-audio information.
10. The method of claim 7 , comprising step (i) wherein said decoder links said user to an Internet document determined by an address formed by said decoded embedded non-audio information.
11. The method of claim 6 , wherein said audio samples are represented in frequency domain.
12. A method for encoding non-audio information with a compressed audio file, comprising the steps of:
(1) receiving a non compressed or compressed audio file;
(2) receiving at least one non-audio data stream;
(3) identifying at least one modifiable block within said non compressed or compressed audio file, said modifiable block including an audio sample having a maximum value exceeding an audio quality threshold value; and
(4) modifying a portion of at least one said modifiable block of said audio file to encode therein each said non-audio data stream at a selected point in the audio stream such that each said non-audio data stream is reproducible by a decoder at a selected time interval along with the audio within said audio file.