Digital audio reproducing apparatus

• US 6,775,654 B1
• Filed: 08/31/1999
• Issued: 08/10/2004
• Est. Priority Date: 08/31/1998
• Status: Expired due to Fees

• Current Assignee: Fujitsu Advanced Engineering Limited (Fujitsu Limited), Fujitsu Limited
• Original Assignee: Fujitsu Advanced Engineering Limited (Fujitsu Limited), Fujitsu Limited
• Inventors: Katoh, Tadayoshi, Matsushima, Kazuhisa, Saito, Takashi, Okubo, Hiroshi, Yokoyama, Hideaki
• Primary Examiner(s): Dorvil, Richemond
• Assistant Examiner(s): NOLAN, DANIEL A
• Application Number:
  US09/387,156
• Time in Patent Office: 1,806 Days
• Field of Search: 704/500, 704/503, 704/200, 704/255, 704/201, 704/220, 704/226, 704/228, 714/758, 714/747, 714/755, 375/136
• US Class Current: 704/500
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm

Abstract

A digital audio reproducing apparatus including a receiver receiving modulated data, a demodulator demodulating the modulated data received by the receiver, an audio decoder decoding, in a unit of a frame, digital audio information contained in the modulated data demodulated by the demodulator, and an audibility corrector for effecting audibility correction on failing digital audio information contained in a frame that failed to be decoded, when the audio decoder fails to decode the digital audio information.

Claims

1. A digital audio reproducing apparatus, comprising:

receiving means for receiving modulated data containing coded digital audio information, said digital audio information being separated from an audio signal and a picture signal, said modulated data sent in a unit of a frame;

demodulating means for demodulating the modulated data received by the receiving means;

audio decoding means for decoding in a unit of a frame digital audio information contained in the modulated data demodulated by the demodulating means; and

audibility correcting means for carrying out audibility correction by using at least one digital audio information out of;

first digital audio information that has been sent before failing digital audio information accommodated in a frame failed to be decoded and has been successfully decoded by the audio decoding means, and

second digital audio formation that has been sent after the failing digital audio information and has been successfully decoded by the audio decoding means

said one digital audio information being obtained by calculating a predetermined data multiplied with a weighting, when the audio decoding means fails to decode the digital audio information,

wherein the audibility correcting means is arranged to carry out the audibility correction by using both of the first digital audio information and the second digital audio information.

2. A digital audio reproducing apparatus according to claim 1, wherein the audibility correcting means further comprises a first smoothing processing means for smoothing the boundary between corrected data that has been subjected to the audibility correction by using the first digital audio information or the second digital audio information and non-corrected data that has not been subjected to the audibility correction.

3. A digital audio reproducing apparatus according to claim 1, wherein the audibility correcting means is arranged to effect an averaging processing with an inclined weight distribution on the first digital audio information and the second digital audio information to create correction data, whereby the audibility correction is carried out.

4. A digital audio reproducing apparatus, comprising:

receiving means for receiving modulated data containing coded digital audio information, said digital audio information being separated from an audio signal and a picture signal, said modulated data sent in a unit of a frame;

demodulating means for demodulating the modulated data received by the receiving means;

audio decoding means for decoding in a unit of a frame digital audio information contained in the modulated data demodulated by the demodulating means;

audibility correcting means for deleting failing digital audio information accommodated in a frame that failed to be decoded, and inserting a normally decoded audio data which is/are placed at a first and/or a second position close to the failing digital audio information, to carry out audibility correction of thus obtained connecting portion, when the audio decoding means fails to decode the digital audio information; and

time adjusting data inserting means for inserting time adjusting data useful for correcting a time lag caused when the audibility correcting means deletes the failing digital audio information,

wherein the audibility correcting means is arranged such that when the audibility correcting means deletes the failing digital audio information and places pieces of the digital audio information neighboring the failing digital audio information close to each other thereby to carry out the audibility correction, the audibility correcting means selects a position at which the pieces of the digital audio information neighboring the failing digital audio information have the audio signal levels and the audio signal slopes most coincident to each other, said position having a high correlation of a part of the audio signal of a frame before the deleted frame and a part of the audio signal having a high correlation of a frame following the deleted frame.

5. A digital audio reproducing apparatus according to claim 4 wherein the audibility correcting means further comprises second smoothing processing means for smoothing the boundary that is caused when the audibility correcting means deletes the failing digital audio information and places the pieces of the digital audio information neighboring the failing digital audio information close to each other.

6. A digital audio reproducing apparatus, comprising:

receiving means for receiving modulated data containing coded digital audio information, said digital audio information being separated from an audio signal and a picture signal, said modulated data sent in a unit of a frame;

demodulating means for demodulating the modulated data received by the receiving means;

audio decoding means for decoding in a unit of a frame digital audio information contained in the modulated data demodulated by the demodulating means;

audibility correcting means for deleting failing digital audio information accommodated in a frame that failed to be decoded, and inserting a normally decoded audio data which is/are placed at a first and/or a second position close to the failing digital audio information, to carry out audibility correction of thus obtained connecting portion, when the audio decoding means fails to decode the digital audio information; and

time adjusting data inserting means for inserting time adjusting data useful for correcting a time lag caused when the audibility correcting means deletes the failing digital audio information,

wherein the time adjusting data inserting means is arranged to insert 0-level data, whose level is 0, or minute level data, whose level is minute into the digital audio data at a position with a relatively low audio signal level.

7. A digital audio reproducing apparatus comprising:

receiving means for receiving modulated data containing coded digital audio information, said digital audio information being separated from an audio signal and a picture signal, sent in a unit of frame, demodulating means for demodulating the modulated data received by the receiving means;

audio decoding means for decoding digital audio information contained in the modulated data demodulated by the demodulating means;

audibility correcting means for carrying out audibility correction in such a manner that, when the audio decoding means fails to decode the digital audio information, the audibility correcting means deletes failing digital audio information accommodated in a frame failed to be decoded, transforms first digital audio information having a time dimension that has been sent before the failing digital audio information and has been successfully decoded by the audio decoding means and second digital audio information having the time dimension that has been sent after the failing digital audio information and has been successfully decoded by the audio decoding means, into a frequency domain, creates intermediate frequency domain digital audio information from the first digital audio information and the second digital audio information having the frequency dimension after the transform, applies inverse transform on the intermediate frequency domain digital audio information to obtain intermediate digital audio information having the time dimension and weights and places the intermediate digital audio information at the position where the failing digital audio information is deleted or a vicinity thereof, whereby the audibility correction is achieved, and

said audibility correcting means is arranged to multiply the intermediate digital audio information with a first window function to obtain first digital audio information and multiply digital audio information, the digital audio information being inserted at the position where the failing digital audio information is deleted or a vicinity thereof, with a second window function, to obtain a second digital audio information and place the first digital audio information and the second digital audio information at the position where the failing digital audio information is deleted or a vicinity thereof.