Bitstream conversion method, bitstream conversion apparatus, bitstream connecting apparatus, bitstream splitting program, bitstream conversion program, and bitstream connecting program

1. A bitstream conversion method for converting a bitstream of a first format, containing content data, into a bitstream of a second format, comprising:

splitting the bitstream of the first format in time sequential fashion into a plurality of split bitstreams of the first format so as to provide an overlapping portion at each splitting position;

converting the plurality of split bitstreams of the first format in a parallel fashion into a plurality of split bitstreams of the second format; and

connecting the plurality of split bitstreams of the second format to one another,

wherein the bitstream of the first format contains a moving image stream and an audio stream, and

wherein the overlapping portion at each splitting position of the audio stream is made to have a longer time length than the overlapping portion at each splitting position of the moving image stream has.

2. The bitstream conversion method as claimed in claim 1 , wherein the bitstream of the first format contains a moving image stream, the method further comprising:

for each key frame contained in the overlapping portion of the split bitstreams of the second format, generating prescribed auxiliary information that is referred to in order to select a connecting position at which to connect together the split bitstreams of the second format;

when connecting the plurality of split bitstreams of the second format to one another, determining each connecting frame position by selecting a key frame position where the difference between the auxiliary information generated for one stream and the auxiliary information generated for an ensuing stream is the smallest; and

connecting the one stream to the ensuing stream at the connecting frame position.

3. The bitstream conversion method as claimed in claim 2 , wherein the auxiliary information includes at least information indicating picture quality of the key frame and the amount of information that occurs.

4. The bitstream conversion method as claimed in claim 2 , wherein when the connecting frame position that satisfies a predetermined condition is not found, the conversion is redone for the bitstream in the overlapping portion.

5. A bitstream conversion apparatus for converting a bitstream of a first format, containing content data, into a bitstream of a second format, comprising:

a splitting unit which splits the bitstream of the first format in time sequential fashion into a plurality of split bitstreams of the first format;

a plurality of conversion units which convert the plurality of split bitstreams of the first format into a plurality of split bitstreams of the second format; and

a connecting unit which connects the plurality of split bitstreams of the second format to one another,

wherein the splitting unit splits the bitstream of the first format so as to provide an overlapping portion at each splitting position;

wherein the bitstream of the first format contains a moving image stream and an audio stream, and

wherein the splitting unit sets the overlapping portion at each splitting position of the audio stream so as to have a longer time length than the overlapping portion at each splitting position of the moving image stream has.

6. The bitstream conversion apparatus as claimed in claim 5 ,

wherein the bitstream of the first format contains a moving image stream,

wherein each of the conversion units includes an auxiliary information generating unit which, for each key frame contained in the overlapping portion of the split bitstreams of the second format, generates prescribed auxiliary information that is referred to in order to select a connecting position at which to connect together the split bitstreams of the second format, and

wherein the connecting unit includes:

a connecting frame position determining unit which determines a connecting frame position for connecting one stream to an ensuing stream by selecting a key frame position where the difference between the auxiliary information generated for the one stream and the auxiliary information generated for the ensuing stream is the smallest; and

a data connecting unit which connects the one stream to the ensuing stream at the connecting frame position.

7. The bitstream conversion apparatus as claimed in claim 6 , wherein the auxiliary information includes at least information indicating picture quality of each frame and the amount of information that occurs.

8. The bitstream conversion apparatus as claimed in claim 6 , wherein when the connecting frame position that satisfies a predetermined condition is not found, the conversion unit redoes the conversion for the bitstream in the overlapping portion.

9. A non-transitory computer-readable storage medium storing a bitstream splitting program which, when executed by a computer for bitstream splitting process, causes the computer for bitstream splitting process to execute a process comprising:

splitting a bitstream of a first format, containing content data, in time sequential fashion into a plurality of split bitstreams of the first format which are to be converted into a plurality of split bitstreams of the second format in a parallel fashion by a plurality of conversion units, so as to provide an overlapping portion at each splitting position,

wherein the bitstream of the first format contains a moving image stream and an audio stream, and the overlapping portion at each splitting position of the audio stream is made to have a longer time length than the overlapping portion at each splitting position of the moving image stream has.

10. A non-transitory computer-readable storage medium storing a bitstream conversion program for converting the split bitstream of the first format containing at least a moving image stream, provided by the bitstream splitting program stored in the non-transitory computer-readable storage medium of claim 9 , when the bitstream conversion program is executed by a computer for bitstream conversion process, the bitstream conversion program causing the computer for bitstream conversion process to execute a process comprising:

converting the split bitstream of the first format into the split bitstream of the second format, and

generating, for each key frame contained in the overlapping portion of the split bitstream of the second format, prescribed auxiliary information that is referred to in order to select a connecting position at which to connect together the split bitstreams of the second format.

11. The non-transitory computer-readable storage medium as claimed in claim 10 , wherein the auxiliary information includes at least information indicating picture quality of the key frame and the amount of information that occurs.

12. A non-transitory computer-readable storage medium storing a bitstream connecting program for connecting the plurality of split bitstreams of the second format to one another, provided by the bitstream conversion program stored in the non-transitory computer-readable storage medium of claim 10 , when the bitstream connecting program is executed by a computer for bitstream connecting process, the bitstream connecting program causing the computer for bitstream connecting process to execute a process comprising:

determining a connecting position for connecting one stream to an ensuing stream by selecting a key frame position where the difference between the auxiliary information generated for the one stream and the auxiliary information generated for the ensuing stream is the smallest; and

connecting the one stream to the ensuing stream at the thus determined connecting position.

13. The non-transitory computer-readable storage medium storing the bitstream conversion program providing split bitstream of the second format to the bitstream connecting program stored in the non-transitory computer-readable storage medium of claim 12 , the bitstream conversion program causing the computer for bitstream conversion process to execute the process further comprising:

reconverting the bitstream in the overlapping portion when the computer for bitstream connecting process on which the bitstream connecting program is run is unable to find the connecting frame position that satisfies a predetermined condition.

14. The bitstream conversion method as claimed in claim 3 , wherein when the connecting frame position that satisfies a predetermined condition is not found, the conversion is redone for the bitstream in the overlapping portion.

15. The bitstream conversion apparatus as claimed in claim 7 , wherein when the connecting frame position that satisfies a predetermined condition is not found, the conversion unit redoes the conversion for the bitstream in the overlapping portion.