Remove an extra frame copy that wasn't needed. Only update the stored frame if the previous frame had been displayed. Don't render the same frame again if there's no new frame to update.

jni/nv_avc_dec/nv_avc_dec.c

@@ -12,12 +12,10 @@ AVCodec* decoder;
 AVCodecContext* decoder_ctx;
 AVFrame* yuv_frame;
 AVFrame* rgb_frame;
-AVFrame* rnd_frame;
 AVFrame* dec_frame;
 pthread_mutex_t mutex;
 char* rgb_frame_buf;
 struct SwsContext* scaler_ctx;
-int picture_new;
 
 #define RENDER_PIX_FMT AV_PIX_FMT_RGBA
 #define BYTES_PER_PIXEL 4
@@ -161,43 +159,31 @@ void nv_avc_destroy(void) {
 		av_free(rgb_frame_buf);
 		rgb_frame_buf = NULL;
 	}
-	if (rnd_frame) {
-		av_frame_free(&rnd_frame);
-		rnd_frame = NULL;
-	}
 	pthread_mutex_destroy(&mutex);
 }
 
 void nv_avc_redraw(JNIEnv *env, jobject surface) {
 	ANativeWindow* window;
 	ANativeWindow_Buffer buffer;
+	AVFrame *our_yuv_frame;
 	int err;
 
-	// Free the old decoded frame
-	if (rnd_frame) {
-		av_frame_free(&rnd_frame);
-	}
-
 	pthread_mutex_lock(&mutex);
 
 	// Check if there's a new frame
-	if (picture_new) {
+	if (yuv_frame) {
-		// Clone the decoder's last frame
+		// We now own the decoder's frame and are
-		rnd_frame = av_frame_clone(yuv_frame);
+		// responsible for freeing it when we're done
+		our_yuv_frame = yuv_frame;
+		yuv_frame = NULL;
 
 		// The remaining processing can be done without the mutex
 		pthread_mutex_unlock(&mutex);
 
-		if (rnd_frame == NULL) {
-			__android_log_write(ANDROID_LOG_ERROR, "NVAVCDEC",
-					"Cloning failed");
-			return;
-		}
-
 		// Convert the YUV image to RGB
 		err = sws_scale(scaler_ctx,
-			rnd_frame->data,
+			our_yuv_frame->data,
-			rnd_frame->linesize,
+			our_yuv_frame->linesize,
 			0,
 			decoder_ctx->height,
 			rgb_frame->data,
@@ -205,14 +191,14 @@ void nv_avc_redraw(JNIEnv *env, jobject surface) {
 		if (err != decoder_ctx->height) {
 			__android_log_write(ANDROID_LOG_ERROR, "NVAVCDEC",
 					"Scaling failed");
-			return;
+			goto free_frame_and_return;
 		}
 
 		window = ANativeWindow_fromSurface(env, surface);
 		if (window == NULL) {
 			__android_log_write(ANDROID_LOG_ERROR, "NVAVCDEC",
 					"Failed to get window from surface");
-			return;
+			goto free_frame_and_return;
 		}
 
 		// Lock down a render buffer
@@ -236,10 +222,12 @@ void nv_avc_redraw(JNIEnv *env, jobject surface) {
 		}
 
 		ANativeWindow_release(window);
+		
+	free_frame_and_return:
+		av_frame_free(&our_yuv_frame);
 	}
 	else {
 		pthread_mutex_unlock(&mutex);
-		rnd_frame = NULL;
 	}
 }
 
@@ -272,25 +260,18 @@ int nv_avc_decode(unsigned char* indata, int inlen) {
 		}
 
 		if (got_pic) {
-			// Update the frame if it's not being read
+			pthread_mutex_lock(&mutex);
-			if (pthread_mutex_trylock(&mutex) == 0) {
-				// Free the old frame
-				if (yuv_frame) {
-					av_frame_free(&yuv_frame);
-				}
 
+			// Only clone this frame if the last frame was taken.
+			// This saves on extra copies for frames that don't get
+			// rendered.
+			if (yuv_frame == NULL) {
 				// Clone a new frame
 				yuv_frame = av_frame_clone(dec_frame);
-				if (yuv_frame) {
-					picture_new = 1;
-				}
-				else {
-					picture_new = 0;
 			}
 
 			pthread_mutex_unlock(&mutex);
 		}
-		}
 
 		pkt.size -= err;
 		pkt.data += err;