Claims
- 1. A method of synchronizing audio and video portions of a media program signal, comprising the steps of:
detecting an audio event in the audio portion of the media program signal; measuring a timing interval from the audio event to a subsequent video synchronization pulse in the video portion of the media program signal; and storing the timing interval in a third portion of the media program signal.
- 2. The method of claim 1, wherein the third portion of the media program signal is a closed-captioning portion of the media program signal.
- 3. The method of claim 1, wherein the audio event comprises a start of sentence, and the step of detecting the audio event comprises the steps of:
determining a silence interval Δtsilence during which an amplitude of the audio portion of the media program signal remains below a silence threshold Tsilence for a minimum silence interval time period min Δtsilence; and identifying the start of sentence as a time after the silence interval Δtsilence and in which the audio portion of the media program signal rises from below the silence threshold Tsilence to above a syllable threshold Tsyllable within a syllable rise time Δtsyllable.
- 4. The method of claim 3, wherein:
min Δtsilence is approximately 20 milliseconds; Tsilence is approximately 26 dB below an AGC threshold; Tsyllable is approximately 6 dB below the AGC threshold; Δtsyllable is less than two milliseconds.
- 5. The method of claim 1, wherein the audio event comprises the steps of:
generating a monaural signal from the audio portion if the audio portion comprises greater than one channel.
- 6. The method of claim 5, wherein the audio event is a start of sentence and step of detecting the audio event further comprises the steps of:
bandpass filtering the audio signal to approximately a vocal bandpass range; and normalizing an audio level of the bandpass filtered audio signal according to an automatic gain control (AGC) threshold.
- 7. The method of claim 6, further comprising the steps of:
rectifying the audio level-normalized and bandpass filtered audio signal; and low pass filtering the rectified, audio level normalized and bandpass filtered audio signal.
- 8. The method of claim 1, wherein the step of storing the timing interval in a third portion of the media program signal comprises the step of:
associating the time interval with one of a plurality of non-printing timing reference characters; storing the non-printing reference characters.
- 9. A method of synchronizing audio and video portions of a media program signal, comprising the steps of:
reading a timing interval in a third portion of the media program signal, the timing interval describing a timing interval from the start of a sentence to a subsequent video synchronization pulse in the video portion of the media; and synchronizing the audio and video portions of the media program according to the timing interval.
- 10. The method of claim 9, wherein third portion of the media program signal is a closed-captioning portion of the media program signal.
- 11. An apparatus for synchronizing audio and video portions of a media program signal, comprising:
means for detecting an audio event in the audio portion of the media program signal; means for measuring a timing interval from the audio event to a subsequent video synchronization pulse in the video portion of the media program signal; and means for storing the timing interval in a third portion of the media program signal.
- 12. The apparatus of claim 11, wherein the third portion of the media program signal is a closed-captioning portion of the media program signal.
- 13. The apparatus of claim 11, wherein the audio event comprises a start of sentence and the means for the audio event comprises:
means for determining a silence interval Δtsilence during which an amplitude of the audio portion fo the media program signal remains below a silence threshold Tsilence for a minimum silence interval time period min Δtsilence; and means for identifying the start of sentence as a time after the silence interval Δtsilence and in which the audio portion of the media program signal rises from below the silence threshold Tsilence to above a syllable threshold Tsyllable within a syllable rise time Δtsyllable.
- 14. The apparatus of claim 13, wherein:
min Δtsilence is approximately 20 milliseconds; Tsilence is approximately 26 dB below an AGC threshold; Tsyllable is approximately 6 dB below the AGC threshold; and Δtsyllable is less than two milliseconds.
- 15. The apparatus of claim 11, wherein the means for detecting the audio event comprises:
means for generating a monaural signal from the audio portion if the audio portion comprises greater than one channel.
- 16. The apparatus of claim 15, wherein the audio event comprises a start of sentence, and the means for detecting the audio event further comprises:
means for bandpass filtering the audio signal to approximately a vocal bandpass range; and means for normalizing an audio level of the bandpass filtered audio signal according to an automatic gain control (AGC) threshold.
- 17. The apparatus of claim 16, further comprising:
means for rectifying the audio level-normalized and bandpass filtered audio signal; and means for low pass filtering the rectified, audio level normalized and bandpass filtered audio signal.
- 18. The apparatus of claim 11, wherein the means for storing the timing interval in a third portion of the media program signal comprises:
means for associating the time interval with one of a plurality of non-printing timing reference characters; means for storing the non-printing reference characters.
- 19. An apparatus of synchronizing audio and video portions of a media program signal, comprising:
means for reading a timing interval in a third portion of the media program signal, the timing interval describing a timing interval from the start of a sentence to a subsequent video synchronization pulse in the video portion of the media; and means for synchronizing the audio and video portions of the media program according to the timing interval.
- 20. The apparatus of claim 19, wherein third portion of the media program signal is a closed-captioning portion of the media program signal.
- 21. An apparatus for synchronizing audio and video portions of a media program signal, comprising:
an audio event detector for detecting an audio event in the audio portion of the media program signal; timer for measuring the timing interval from the audio event to a subsequent video synchronization pulse in the video portion of the media program signal; and a processor for storing the timing interval in a third portion of the media program signal.
- 22. The apparatus of claim 21, wherein the third portion of the media program signal is a closed-captioning portion of the media program signal.
- 23. The apparatus of claim 22, wherein the audio event detector comprises:
a bandpass filter for filtering the audio portion of the media program signal; and an automatic gain control module for normalizing an audio level of the bandpass filtered audio signal according to an automatic gain control (AGC) threshold.
- 24. The apparatus of claim 23, wherein the audio event detector further comprises:
a rectifier for rectifying the audio level-normalized and bandpass filtered audio signal; and a low pass filter for filtering the rectified, audio level normalized and bandpass filtered audio signal.
- 25. The apparatus of claim 24, wherein the audio event detector comprises a voice detector which determines a silence interval Δtsilence during which an amplitude of the normalized audio signal remains below a silence threshold Tsilence for a minimum silence interval time period min Δtsilence and identifies the start of sentence as a time after the silence interval Δtsilence and in which the audio portion of the media program signal rises from below the silence threshold Tsilence to above a syllable threshold Tsyllable within a syllable rise time Δtsyllable.
- 26. The apparatus of claim 25, wherein:
min Δtsilence is approximately 20 milliseconds; Tsilence is approximately 26 dB below an AGC threshold; Tsyllable is approximately 6 dB below the AGC threshold; and Δtsyllable is less than two milliseconds..
- 27. The apparatus of claim 21, wherein the processor associates the time interval with one of a plurality of non-printing timing reference characters and for storing the non-printing reference characters in the memory.
- 28. An apparatus of synchronizing audio and video portions of a media program signal, comprising:
a synchronizing detector for reading a timing interval in a third portion of the media program signal, the timing interval describing a timing interval from the start of a sentence to a subsequent video synchronization pulse in the video portion of the media; and a synchronizer, communicatively coupled to the synchronizing detector synchronizing the audio and video portions of the media program according to the timing interval.
- 29. The apparatus of claim 28, wherein third portion of the media program signal is a closed-captioning portion of the media program signal.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional Patent Application No. 60/409,346 entitled “METHOD AND APPARATUS FOR LIPSYNC MEASUREMENT AND CORRECTION,” by Leon J. Stanger, filed Sep. 9, 2002, which application is hereby incorporated by reference herein.
Provisional Applications (1)
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Number |
Date |
Country |
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60409346 |
Sep 2002 |
US |