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using:b-frames [2010/04/15 18:27] j.m |
using:b-frames [2010/04/16 19:47] j.m |
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Video frames can be divided among 3 types: | Video frames can be divided among 3 types: | ||
- | - [[I-frames|I-Frame]]: Intra frame, also called keyframe. They have no reference frame and can be decoded on their own. They can be thought of as a JPEG image. | + | - **[[I-frames|I-Frame]]:** Intra frame, also called keyframe. They have no reference frame and can be decoded on their own. They can be thought of as a JPEG image. |
- | - P-Frame: Predicted frame. They are deduced from the previous frame (I or P) and cannot be built if the decoder has not decoded the previous frames. | + | - **P-Frame:** Predicted frame. They are deduced from the previous frame (I or P) and cannot be built if the decoder has not decoded the previous frames. |
- | - B-Frame: They are decoded from the previous and next I-P frames. | + | - **B-Frame:** They are decoded from the previous and next I-P frames. |
B-frames are interesting for two facts. First, they have a slightly better prediction. And second and more important, they do not impact the quality of following frames, so they can be encoded with lower quality without degrading the whole sequence. | B-frames are interesting for two facts. First, they have a slightly better prediction. And second and more important, they do not impact the quality of following frames, so they can be encoded with lower quality without degrading the whole sequence. |