The execution time of the start() method of FFmpegFrameGrabber is too long, which may be because the FFmpeg library needs to perform some initialization operations, such as opening video files, reading video stream information, and initializing decoders. These operations take a certain amount of time. In some cases, it may be necessary to optimize the execution efficiency of these operations to improve the responsiveness and performance of the program.
Here are some possible optimization suggestions:
Adjust video codec parameters
When the FFmpegFrameGrabber object is initialized, the name of the video decoder or the parameters of the video decoder can be set through the setVideoCodecName() method to speed up the initialization process of the video decoder. For example, parameters such as the number of threads of the video decoder and the output pixel format of the decoder can be set to improve the performance of the decoder.
Adjust video frame rate and resolution
If the video frame rate and resolution are too high, it will increase the load on the decoder, resulting in slower execution efficiency. You can reduce the video frame rate and resolution through the setFrameRate() method and the setImageWidth() and setImageHeight() methods to improve the response speed and performance of the program.
Use hardware decoder
On devices that support hardware decoders, you can use the FFmpegFrameGrabber.setOption() method to set the hardware decoder as the preferred decoder to speed up the initialization process of the video decoder. For example, you can set "-vcodec h264_cuvid" or "-vcodec hevc_cuvid" to use NVIDIA's hardware codec.
Specify the buffer size of the decoder
If the video file is large, the decoder may run out of buffers, slowing down the initialization process. The buffer size of the decoder can be set through the FFmpegFrameGrabber.setOption() method to speed up the initialization process. For example, you can set "-probesize 32" or "-max_probe_packets 32" to increase the buffer size of the decoder.
cache video stream data
Before calling the FFmpegFrameGrabber.start() method, you can use the FFmpegFrameGrabber.setOption() method to set the size and cache time of the buffer area to cache video stream data to improve the execution efficiency of the initialization process. For example, you can set "-rtbufsize 200M" or "-stimeout 2000000" to increase the buffer size and buffer time.
It should be noted that different optimization methods are suitable for different application scenarios and environments. In practical applications, it is necessary to select the most suitable optimization method according to the specific situation.