Get all frames from video using MediaMetadataRetriever

user_7954210 0
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I'm trying to get all frames from a video using MediaMetadataRetriever and getFrameAt() method. Using FFMPEG, I've got the following information :

  1. Video frame counts : 234 frames

  2. Video duration in milliseconds : 90000

    int counter = 0;
long mVideoDuration = 9000;
for (long i = 0; i < mVideoDuration * 1000; i += 1000) {
    Bitmap thumbnail = mMediaMetadataRetriever.getFrameAtTime(i);
}

The above code does not work, it's loop for almost 8944 times, and this is too much, I don't want to get all these frames, I just want to get the 234 frames.

getFrameAtIndex() WORKS VERY WELL, but due to API level compatibility, I would like to make it work with getFrameAt() method

mediametadataretriever android java
1 Answers

To get the frames with getFrameeAtTime() youd have to know the time of every frame in the video. You could roughly calculate that if u already know the frame count by getting the frametime (duration/frames), taking the math.ceil() method on that and taking that as your incrementor. however, youd have to check if the last frame gets read since u can't always get the exact frame time, bc they tend to have alot of decimal places wich can lead to wrong representation as float. A 60fps video for example would have a frame time of 16+1/3 ms. Wich has infinite deecimal places. In addition this method wouldn't even work at all if you have a video with too high fps since in that case the round up done by math.ceil() can lead to a big enough margin to skip frames. To be precise this method only works if:

(math.ceil(frameTime)-frameTime)⋅frameCount<frameTime

I hope, by now u got that it's a pretty bad idea and u should probably use another way to get the individual frames. But still, heres an implementation:

int lastTime;
long mVideoDuration = 9000;
mVideoDuration*=1000;
int frameTime=math.ceil(mVideoDuration/frameCount)
for(int i =0, i<=mVideoDuration, i+=frameTime){
    Bitmap thumbnail = mMediaMetadataRetriever.getFrameAtTime(i);
    lastTime=i;
}
if (lastTime<mVideoDuration){
   mMediaMetadataRetriever.getFrameAtTime(mVideoDuration);
}

Of couse this is already assuming that,

(math.ceil(frameTime)-frameTime)⋅frameCount<frameTime

is given. And i can't guarantee that the declaframeTime will result the correct value since i dont know exactly how decimal dividing is handleed internally and its entirely possible that is causes problems due to floating point overflow

user_183112430
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