Method and apparatus for providing scalable pre-compressed digital video with reduced quantization based artifacts

A method of providing a scalable digital video sequence, the method comprising:

• providing a first bitstream having interframe coding at a first coarseness of quantization and a first bit rate, the first bitstream being coded from an input video signal;
• providing a second bitstream having interframe coding at a second coarseness of quantization and a second bit rate which is different than the first bit rate, the second bitstream being coded from an input signal comprising said video signal and a reconstructed frame of said video signal reconstructed from the first bitstream such that the reconstructed frame has a quantization error corresponding to the first predetermined coarseness of quantization;
• providing, as an output, a portion of the first bitstream;
• and
• switching said output from the first bitstream to the second bitstream in a temporally contiguous manner relative to the video sequence, such that video images coded in the output portion of the second bitstream continue where video images coded in the output portion of the first bitstream left off, and decoding of said output results in a continuous video sequence.

A digital motion video coding apparatus for coding a digital video sequence at a plurality of different bit rates from an input video signal, the video sequence comprising multiple bitstreams each having a plurality of data organized in a plurality of temporally sequential spatial frames, the apparatus comprising:

• a first interframe coder which interframe codes the video signal with a first predetermined coarseness of quantization to generate a first interframe coded bitstream having a first bit rate;
• means for reconstructing a frame of the video signal from the first interframe coded bitstream to generate a reconstructed frame having a quantization error corresponding to the first predetermined coarseness of quantization;
• a second interframe coder which interframe codes the video signal with a second predetermined coarseness of quantization to generate a second interframe coded bitstream having a second bit rate which is different than the first bit rate, such that each of the first and second bitstreams is an independently viewable version of the video signal at a different coarseness of quantization;
• and
• means for inputting the reconstructed frame to the second interframe coder with the input video signal such that the second interframe coded bitstream includes an interframe coded version of the reconstructed frame.

A video-on-demand server for providing digital motion video at a plurality of different bit rates comprising:

• means for providing a first bitstream having interframe coding at a first coarseness of quantization and a first bit rate, the first bitstream being coded from an input video signal;
• means for providing a second bitstream having interframe coding at a second coarseness of quantization and a second bit rate which is different than the first bit rate, the second bitstream being coded from said input video signal and from a reconstructed frame of said video signal reconstructed from the first bitstream such that the reconstructed frame has a quantization error corresponding to the first coarseness of quantization;
• means for providing, as an output, a portion of the first bitstream;
• and
• means for switching said output from the first bitstream to the second bitstream in a temporally contiguous manner relative to the video sequence, such that video images coded in the output portion of the second bitstream continue where video images coded in the output portion of the first bitstream left off, and decoding of said output results in a continuous video sequence.

A server for providing digital motion video at a plurality of different bit rates comprising:

• a source of a first bitstream interframe coded from an input video signal for interframe decoding at a first bit rate, the first bitstream comprising video data that, when decoded, corresponds to a first predetermined video sequence;
• a source of a second bitstream interframe coded from said input video signal for interframe decoding at a second bit rate different than the first bit rate, the second bitstream comprising video data that, when decoded, provides a continuation of said predetermined video sequence;
• and
• a source of transition data that, when decoded by an interframe decoder that was used to decode the first bitstream immediately prior thereto, compensates for visual discrepancies between a decoded version of the first bitstream and a decoded version of the second bitstream, such that decoding of the second bitstream with said decoder immediately after decoding the transition data provides a continuation of the predetermined video sequence without visual artifacts that would otherwise be present due to the difference in the bit rates of the first and second bitstreams.

A digital motion video coding apparatus for coding a video sequence at a plurality of different bit rates from an input video signal, the video sequence comprising multiple bitstreams each having a plurality of data organized in a plurality of temporally sequential spatial frames, the apparatus comprising:

• a first interframe coder that interframe codes the video signal to a first bitstream that is to be decoded at a first bit rate;
• a second interframe coder that interframe codes the video signal to a second bitstream that is to be decoded at a second bit rate different than the first bit rate;
• and
• a switch frame coder that interframe codes transition data that, when decoded by an interframe decoder that was used to decode the first bitstream immediately prior thereto, compensates for visual discrepancies between a decoded version of the first bitstream and a decoded version of the second bitstream, such that decoding of the second bitstream with said decoder immediately after decoding the transition data provides a continuation of the video sequence without visual artifacts that would otherwise be present due to the difference in the bit rates of the first and second bitstreams.

A method of providing digital motion video at a plurality of different bit rates, the method comprising:

• decoding, at a first bit rate, a first bitstream that was interframe coded from an input video signal, the first bitstream comprising video data that, when decoded, corresponds to a first predetermined video sequence;
• decoding, at a second bit rate different than the first bit rate, a second bitstream that was interframe coded from said input video signal, the second bitstream comprising video data that, when decoded, provides a continuation of said predetermined video sequence;
• and
• decoding, after decoding the first bitstream and before decoding the second bitstream, transition data that compensates for visual discrepancies between a decoded version of the first bitstream and a decoded version of the second bitstream, such that decoding of the second bitstream immediately after decoding the transition data provides a continuation of the predetermined video sequence without visual artifacts that would otherwise be present due to the difference in the bit rates of the first and second bitstreams.

A method of providing a scalable digital video sequence, the method comprising:

• providing a first bitstream interframe coded from an input video signal at a first bit rate;
• providing a second bitstream interframe coded from said input video signal at a second bit rate different than the first bit rate;
• providing a switch frame comprising the difference between a frame of data of the first bitstream and a frame of data of the second bitstream;
• delivering, as a video output, a portion of the first bitstream;
• switching the video output from the first bitstream to the switch frame in a temporarily contiguous manner relative to the video sequence;
• and
• switching the video output from the switch frame to the second bitstream in a temporarily contiguous manner such that video images represented by the video output represent a continuing video sequence from the first bitstream to the switch frame to the second bitstream.

A method of coding a video sequence at a plurality of different bit rates from an input video signal, the video sequence comprising multiple bitstreams each having a plurality of data organized in a plurality of temporally sequential spatial frames, the apparatus comprising:

• interframe coding the video signal to a first bitstream that is to be decoded at a first bit rate;
• interframe coding the video signal to a second bitstream that is to be decoded at a second bit rate different than the first bit rate;
• and
• interframe coding transition data that, when decoded by an interframe decoder that was used to decode the first bitstream immediately prior thereto, compensates for visual discrepancies between a decoded version of the first bitstream and a decoded version of the second bitstream, such that decoding of the second bitstream with said decoder immediately after decoding the transition data provides a continuation of the video sequence without visual artifacts that would otherwise be present due to the difference in the bit rates of the first and second bitstreams.

A computer program product for use with a digital computer system for facilitating the construction of a video signal, the computer program product comprising a computer readable medium having encoded thereon:

• a first coding module that causes the digital computer system to interframe code an input video signal with a first predetermined coarseness of quantization to generate a first interframe coded bitstream having a first bit rate;
• a reconstruction module that causes the digital computer system to reconstruct a frame of the input video signal from the first interframe coded bitstream to generate a reconstructed frame having a quantization error corresponding to the first predetermined coarseness of quantization;
• the a second coding module that causes the digital computer system to input the video signal to a second or additional interframe coder, which interframe codes the input video signal with a second predetermined coarseness of quantization to generate a second or additional interframe coded bitstream having a second average bit rate which is different than the first bit rate, such that each of the first and second bitstreams is an independently viewable version of the video signal at a different coarseness of quantization;
• and
• a frame insert module that causes the digital computer system to input the reconstructed frame to the second interframe coder with the input video signal such that the second or additional interframe coded bitstream includes a coded frame based on the reconstructed frame.

A computer program product for use with a digital computer system for facilitating the coding of a video sequence at a plurality of different bit rates from an input video signal, the video sequence comprising multiple bitstreams each having a plurality of data organized in a plurality of temporally sequential spatial frames, the computer program product comprising a computer readable medium having encoded thereon:

• a first interframe coding module that causes the digital computer system to interframe code the video signal to a first bitstream that is to be decoded at a first bit rate;
• a second interframe coding module that causes the digital computer system to interframe code the video signal to a second bitstream that is to be decoded at a second bit rate different than the first bit rate;
• and
• a switch frame coding module that causes the digital computer system to interframe code transition data that, when decoded by an interframe decoder that was used to decode the first bitstream immediately prior thereto, compensates for visual discrepancies between a decoded version of the first bitstream and a decoded version of the second bitstream, such that decoding of the second bitstream with said decoder immediately after decoding the transition data provides a continuation of the video sequence without visual artifacts that would otherwise be present due to the difference in the bit rates of the first and second bitstreams.