Method and apparatus for transcoding digital video signals

A machine-readable medium whose contents cause a system to transcode a digital video signal, by performing the steps of:

• receiving a first set of bits encoded in a first encoding format;
• decoding said first set of bits to discrete cosine transform (DCT) coefficients;
• transforming said DCT coefficients into an intermediate exchange format;
• and
• encoding said transformed DCT coefficient using a second encoding format;
• wherein
• said intermediate exchange format comprises a data structure having a first DCT mode and first color format, and wherein said transforming comprises
• determining whether said DCT coefficients were created with said DCT mode and said first color format;
• and
• transforming said DCT coefficients to match said DCT mode and said first color format accordance with said determination.

An apparatus transcoding a first set of bits encoded using a first format into a second set of bits encoded using a second format, comprising;

• a decoder, said decoder having a first input capable of receiving the first set of bits and of encoding them into discrete cosine transform (DCT) coefficients, with said decoder having a first output;
• a transcoder having a second input coupled to said first output, said transcoder capable of receiving said DCT coefficients and of transforming them into an intermediate exchange format, said transcoder having a second input;
• and
• an encoder having a third input coupled to said second output, said encoder capable of receiving said transformed DCT coefficients and of encoding them using the second encoding format;
• wherein
• said intermediate exchange format comprises a data structure having a first DCT mode and first color format, and wherein said transforming comprises
• determining whether said DCT coefficients were created with said DCT mode and said first color format;
• and
• transforming said DCT coefficients to match said DCT mode and said first color format in accordance with said determination.

A transcoding system, comprises:

• a first encoder;
• a decoder operably coupled to said first encoder;
• a transcoder operably coupled to said decoder, said transcoder capable of receiving DCT coefficients from said decoder and of transforming them into an intermediate exchange format;
• a second encoder operably coupled to said transcoder
• said intermediate exchange format comprises a data structure having a first DCT mode and first color format, and wherein said transforming comprises
• determining where said DCT coefficients were created with said DCT mode and said first color format;
• and
• transforming said DCT coefficients to match said DCT mode and said first color format in accordance with said determination.