diff --git a/swash/processing/layers.py b/swash/processing/layers.py
index 7b7fac1..f1090ee 100644
--- a/swash/processing/layers.py
+++ b/swash/processing/layers.py
@@ -55,7 +55,7 @@ vk = np.sqrt((velk[n] ** 2).sum(axis=1))
 
 lines = ax.plot(x, zk[n].T, c="#0066cc")
 quiv = []
-for i in range(10):
+for i in range(len(lines)-1):
     quiv.append(
         ax.quiver(
             x[::50],
@@ -87,4 +87,4 @@ ani = animation.FuncAnimation(
     fig, animate, frames=wl[:, 0].size, interval=20, blit=True
 )
 
-ani.save(out.joinpath("layers.mp4", codec="h265"))
+ani.save(out.joinpath("layers.mp4"))