Compute PTS of intermediate blocks

If several reads are performed for a single captured audio block (e.g.
if the read size is smaller than the captured block), then the provided
timestamp was the same for all packets.

Recompute the timestamp for each of them.

server/src/main/java/com/genymobile/scrcpy/AudioCapture.java

@@ -34,6 +34,7 @@ public final class AudioCapture {
     private AudioRecord recorder;
 
     private final AudioTimestamp timestamp = new AudioTimestamp();
+    private long previousRecorderTimestamp = -1;
     private long previousPts = 0;
     private long nextPts = 0;
 
@@ -145,8 +146,9 @@ public final class AudioCapture {
         long pts;
 
         int ret = recorder.getTimestamp(timestamp, AudioTimestamp.TIMEBASE_MONOTONIC);
-        if (ret == AudioRecord.SUCCESS) {
+        if (ret == AudioRecord.SUCCESS && timestamp.nanoTime != previousRecorderTimestamp) {
             pts = timestamp.nanoTime / 1000;
+            previousRecorderTimestamp = timestamp.nanoTime;
         } else {
             if (nextPts == 0) {
                 Ln.w("Could not get any audio timestamp");