Don't force render first frame when joining.

We currently force render the first frame in all cases. However, when joining
video to an ongoing playback, there is no defined first frame and we should
rather drop frames if we are late until we caught up with the audio playback.

PiperOrigin-RevId: 268698093

library/core/src/main/java/com/google/android/exoplayer2/video/MediaCodecVideoRenderer.java

@@ -800,10 +800,14 @@ public class MediaCodecVideoRenderer extends MediaCodecRenderer {
     }
 
     long elapsedRealtimeNowUs = SystemClock.elapsedRealtime() * 1000;
+    long elapsedSinceLastRenderUs = elapsedRealtimeNowUs - lastRenderTimeUs;
     boolean isStarted = getState() == STATE_STARTED;
-    if (!renderedFirstFrame
-        || (isStarted
-            && shouldForceRenderOutputBuffer(earlyUs, elapsedRealtimeNowUs - lastRenderTimeUs))) {
+    // Don't force output until we joined and always render first frame if not joining.
+    boolean forceRenderOutputBuffer =
+        joiningDeadlineMs == C.TIME_UNSET
+            && (!renderedFirstFrame
+                || (isStarted && shouldForceRenderOutputBuffer(earlyUs, elapsedSinceLastRenderUs)));
+    if (forceRenderOutputBuffer) {
       long releaseTimeNs = System.nanoTime();
       notifyFrameMetadataListener(presentationTimeUs, releaseTimeNs, format);
       if (Util.SDK_INT >= 21) {
@@ -988,6 +992,7 @@ public class MediaCodecVideoRenderer extends MediaCodecRenderer {
    * @return Returns whether to force rendering an output buffer.
    */
   protected boolean shouldForceRenderOutputBuffer(long earlyUs, long elapsedSinceLastRenderUs) {
+    // Force render late buffers every 100ms to avoid frozen video effect.
     return isBufferLate(earlyUs) && elapsedSinceLastRenderUs > 100000;
   }