shithub: libvpx

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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

--- a/vp8/encoder/onyx_if.c

+++ b/vp8/encoder/onyx_if.c

@@ -3771,6 +3771,11 @@

         {

             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++;

@@ -4613,6 +4618,10 @@

         cpi->bits_off_target -= cpi->projected_frame_size;

     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;

--- a/vp8/encoder/ratectrl.c

+++ b/vp8/encoder/ratectrl.c

@@ -1028,6 +1028,11 @@

         {

             // 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