Actual time of “nativeGetTimestamp” in “SurfaceTexture”

问题

I'm writing a video processing app and need to know the actual time of each frame.

The app works fine at first when I used elapsedRealtime To compute the time offset:

long timeOffset = java.lang.System.currentTimeMillis() - android.os.SystemClock.elapsedRealtime();
long actualTime = timestamp + timeOffset;

But when I used another device, I found some device will use uptimeMillis for the SurfaceTexture.timestamp, so the code sould be:

long timeOffset = java.lang.System.currentTimeMillis() - android.os.SystemClock.uptimeMillis();
long actualTime = timestamp + timeOffset;

So my question is, is there any way to know which time source are the device use for SurfaceTexture?

Although I may compute the closest time source at start of app, but I think it may cause another accident that I can't know yet.

Is there any way to know that?

回答1:

MediaCodec doesn't invent the timestamps. The buffers that MediaCodec return only contain the same values for presentationTimeUs as you pass in the presentationTimeUs parameter to queueInputBuffer, or when using Surface input, is set on the input surface using eglPresentationTimeANDROID.

So you need to check with whichever piece of code that actually produces the timestamps to know what time reference they use.

来源：https://stackoverflow.com/questions/52511236/actual-time-of-nativegettimestamp-in-surfacetexture