Decoding speed is too slow from p4 (AUD-5826)

[1tre]

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Issue or Suggestion Description

For my own project, using p4 to decode 1280x720 frames takes about 600 to 900ms of processing time per frame, with an FPS of around 1. However, the readme file states that the FPS for decoding 1280x720 frames is around 4. I wonder where the problem lies.

[houhaiyan]

@1tre Please use the latest branch. The latest branch decoding can achieve an average of 10fps at 720P.