Legal/Patents/Summaries

This page contains synopses of patents filed for by Mozilla. Ownership of the four patents listed here has been transferred to xiph.org, with a defensive-use-only provision.

1120.06NPR (U.S. Application No. 13/235,190)

• Filing Date: September 16, 2011
• Status: PUBLISHED

This application is directed to a system and method for implementing an adaptive time-frequency resolution in audio and video coding systems. The method includes dividing the spectrum of the input signal into a into plurality of bands. For each of the plurality of bands, the method involves determining a characteristic of the content (e.g., tonal or transient content). The time-frequency resolution value to one or more of the plurality of bands is then modified to increase either a time resolution of the band or a frequency resolution of the band, depending on the characteristic of the content. The method further includes determining a cost associated with modifying the time-frequency resolution value of the one or more of the plurality of bands based on an entropy measure of the bands and then altering the modified time-frequency resolution values in a manner that accounts for the coding cost.

1120.08NPR (U.S. Application No. 13/414,368)

• Filing Date:March 7, 2012
• Status: NOT PUBLISHED

This application is directed to a multi-block coding scheme for an audio signal to prevent partial collapse conditions from causing pre-echo compression artifacts. An embodiment of an audio codec described in the application includes a segmentation component that partitions the audio signal into a plurality of tiles, wherein each tile comprises data from a particular segment of time and a particular set of frequencies of the audio signal. The codec may also include a band energy component for determining an energy value for each tile corresponding to a signal component in a respective tile. The codec may further include: 1) an encoder flag tracking component for marking a tile as not collapsed or collapsed based on the energy value in that tile; and 2) a decoder flag tracking component that fills all tiles marked as collapsed with pseudorandom noise at an estimated energy level. At least some of the tiles may experience a change of time-frequency (TF) resolution of each respective tile. If the TF resolution is changed to increase the number of tiles, each resulting tile may be marked with the identical flag state of the original tile. If the TF resolution is changed to decrease the number of tiles, the resulting tile may be marked as not collapsed if any original tile from which the resulting tile is formed is marked as not collapsed, otherwise it is marked as collapsed.

1120.09NPR (U.S. Application No. 13/414,490)

• Filing Date: March 7, 2012
• Status: NOT PUBLISHED

This application is directed to a system and method for bit allocation and band partitioning for gain-shape vector quantization in an audio codec. The method uses an implicit, dynamic scheme to allow an encoder and decoder to recreate a series of bit allocation decisions for gain and shape without transmitting additional side information for each decision, based on the number of bits that are left remaining and available in a given packet. For implementation in practical codecs, the band comprising the allocation of bits for the shape is recursively split into equal partitions until the number of bits allocated to each partition is less than the maximum codebook size.

1120.10NPR (U.S. Application No. 13/414,418)

• Filing Date: March 7, 2012
• Status: NOT PUBLISHED

This application is directed to an audio coding scheme implemented in a codec that eliminates birdie artifacts generated by transform coding methods. A frequency coefficient spreading method invertibly rotates a spectrum of coefficient values based on a defined rotation angle. The rotated spectrum is then quantized, and the rotation operation is then reversed so that a previously sparse spectrum (i.e., one with few non-zero values) becomes one that has many non-zero values. The method further includes arranging the coefficients for a particular partition into a linear array and computing a gain factor for the partition. The method then derives a rotation angle of between 0 and p/4 for successive pairs of coefficients of the linear array based on the gain factor. One or more rotation operations are then applied to successive pairs of coefficients in the linear array using a specific rotation angle and a stride length for each rotation operation.