Clip buffer level to the maximum buffer size in CBR

The buffer level was able to increase indefinitely rather than
being clipped to the maximum buffer size specified by the user.

This change checks the buffrer level and prevents it from
going beyond the upper limit of the buffer.

Change-Id: Ifff55f79d3c018e4d3d77e554b11ada543cc1654

diff --git a/vp8/encoder/onyx_if.c b/vp8/encoder/onyx_if.c
index e5212ac..84202da 100644 (file)
--- a/vp8/encoder/onyx_if.c
+++ b/vp8/encoder/onyx_if.c
@@ -3771,6 +3771,11 @@ static void encode_frame_to_data_rate
         {
             cpi->decimation_count --;
             cpi->bits_off_target += cpi->av_per_frame_bandwidth;
+
+            // Clip the buffer level at the maximum buffer size
+            if (cpi->bits_off_target > cpi->oxcf.maximum_buffer_size)
+                cpi->bits_off_target = cpi->oxcf.maximum_buffer_size;
+
             cm->current_video_frame++;
             cpi->frames_since_key++;
 
@@ -4614,6 +4619,10 @@ static void encode_frame_to_data_rate
     else
         cpi->bits_off_target += cpi->av_per_frame_bandwidth - cpi->projected_frame_size;
 
+    // Clip the buffer level at the maximum buffer size
+    if (cpi->bits_off_target > cpi->oxcf.maximum_buffer_size)
+        cpi->bits_off_target = cpi->oxcf.maximum_buffer_size;
+
     // Rolling monitors of whether we are over or underspending used to help regulate min and Max Q in two pass.
     cpi->rolling_target_bits = ((cpi->rolling_target_bits * 3) + cpi->this_frame_target + 2) / 4;
     cpi->rolling_actual_bits = ((cpi->rolling_actual_bits * 3) + cpi->projected_frame_size + 2) / 4;

diff --git a/vp8/encoder/ratectrl.c b/vp8/encoder/ratectrl.c
index c893b8d..63d0893 100644 (file)
--- a/vp8/encoder/ratectrl.c
+++ b/vp8/encoder/ratectrl.c
@@ -1028,6 +1028,11 @@ static void calc_pframe_target_size(VP8_COMP *cpi)
         {
             // Update the buffer level variable.
             cpi->bits_off_target += cpi->av_per_frame_bandwidth;
+
+            // Clip the buffer level at the maximum buffer size
+            if (cpi->bits_off_target > cpi->oxcf.maximum_buffer_size)
+                cpi->bits_off_target = cpi->oxcf.maximum_buffer_size;
+
             cpi->buffer_level = cpi->bits_off_target;
         }
         else