Transmission apparatus, transmission method, reception apparatus, and reception method
A processing load on a reception side when subtitle graphics data is superimposed on video data is alleviated. A video stream including video data is generated. A subtitle stream including bitmap data is generated, the bitmap data being obtained by converting subtitle graphics data. A container having a predetermined format containing the video stream and the subtitle stream is transmitted. The subtitle stream includes a bitmap conversion table containing conversion information of a color gamut and/or a luminance. On the reception side, subtitle graphics data having characteristics matched with those of target video data of a superimposition destination can be easily obtained by just converting the bitmap data to the subtitle graphics data by using the bitmap conversion table.
1. A transmission apparatus, comprising:
processing circuitry configured to:
generate a video stream that includes video data; and
generate a subtitle stream that includes bitmap data and color conversion information, the bitmap data being obtained by converting subtitle graphics data, the color conversion information including a color identifier identifying a particular color entry, and the color conversion information further including a color table in association with a color gamut or luminance setting for the particular color entry; and
transmission circuitry configured to:
transmit a container that includes the video stream and the subtitle stream.
2. The transmission apparatus according to claim 1 , wherein
the color conversion information includes multiple color tables in association with respective color gamut or luminance settings for the particular color entry.
3. The transmission apparatus according to claim 2 , wherein
each one of the color gamut or luminance settings includes characteristic information of the subtitle graphics data and target video data.
4. The transmission apparatus according to claim 1 , wherein
the subtitle stream further includes characteristic information of the subtitle graphics data before being converted to the bitmap data.
5. A transmission method, comprising:
generating, by processing circuitry of a transmission apparatus, a video stream that includes video data;
generating, by the processing circuitry, a subtitle stream that includes bitmap data and color conversion information, the bitmap data being obtained by converting subtitle graphics data, the color conversion information including a color identifier identifying a particular color entry, and the color conversion information further including a color table in association with a color gamut or luminance setting for the particular color entry; and
transmitting, by transmission circuitry of the transmission apparatus, a container that includes the video stream and the subtitle stream.
6. The transmission method according to claim 5 , wherein
the color conversion information includes multiple color tables in association with respective color gamut or luminance settings for the particular color entry.
7. A reception apparatus, comprising:
reception circuitry configured to:
receive a container that includes a video stream and a subtitle stream, the video stream including video data, the subtitle stream including bitmap data and color conversion information, the bitmap data being obtained by converting original subtitle graphics data, the color conversion information including a color identifier identifying a particular color entry, and the color conversion information further including a color table in association with a color gamut or luminance setting for the particular color entry; and
processing circuitry configured to:
decode the video stream to obtain target video data;
decode the subtitle stream to obtain the bitmap data and the color conversion information;
convert the bitmap data to reconstructed subtitle graphics data by using the color conversion information; and
superimpose the reconstructed subtitle graphics data on the target video data.
8. The reception apparatus according to claim 7 , wherein
the color conversion information includes multiple color tables in association with respective color gamut or luminance settings for the particular color entry, and
the processing circuitry is configured to apply one of the color tables when a corresponding one of the color gamut or luminance settings associated with the one of the color tables matches characteristics of the target video data.
9. The reception apparatus according to claim 7 , wherein
the subtitle stream further includes characteristic information of the original subtitle graphics data before being converted to the bitmap data, and
the processing circuitry is configured to determine a characteristic of the original subtitle graphics data on the basis of the characteristic information.
10. The reception apparatus according to claim 8 , wherein
the processing circuitry is configured to, when none of the color gamut or luminance settings matches the characteristics of the target video data, convert the bitmap data to the reconstructed subtitle graphics data without using the color tables.
11. A reception method, comprising:
receiving, by reception circuitry of a reception apparatus, a container that includes a video stream and a subtitle stream, the video stream including video data, the subtitle stream including bitmap data and color conversion information, the bitmap data being obtained by converting original subtitle graphics data, the color conversion information including a color identifier identifying a particular color entry, and the color conversion information further including a color table in association with a color gamut or luminance setting for the particular color entry;
decoding the video stream to obtain target video data;
decoding the subtitle stream to obtain the bitmap data and the color conversion information;
converting, by processing circuitry of the reception apparatus, the bitmap data to reconstructed subtitle graphics data by using the color conversion information; and
superimposing the reconstructed subtitle graphics data on the target video data.
12. The reception method according to claim 11 , wherein
the color conversion information includes multiple color tables in association with respective color gamut or luminance settings for the particular color entry, and
the method further comprises applying one of the color tables when a corresponding one of the color gamut or luminance settings associated with the one of the color tables matches characteristics of the target video data.