Revert "Prevent double application of min rate in two pass."

This reverts commit 416b7051d7f610ed6d62dff18af7776ec520fd9c.

Reason for revert: it causes visual quality drop as described in b/112953058.

Original change's description:
> Prevent double application of min rate in two pass.
> 
> The initial allocation of bits in the two pass code to each frame
> should be within the min max limits on the command line. However,
> when forming an ARF group the cost of the ARF is shared by frames
> in that group such that the residual bits for a frame could drop below
> the min value. This change prevents the minimum being re-applied
> after the cost of the ARF has been deducted as this may otherwise
> cause low rate sections to overshoot their target.
> 
> Test runs comparing to a baseline run with min and max section pct
> 0-2000% vs one closer to the YT use case (50-150%) suggest that
> this fix not only results in better rate control but also gives a better
> rd outcome.
> 
> For example the HD set vs 0-2000% baseline (opsnr, ssim).
> Old code (50-150):  +0.751, +1.099
> New code(50-150): +0.241, -0.009
> 
> Change-Id: I715da7b130bf53ba8aa609532aa9e18b84f5e2ef

TBR=yaowu@google.com,paulwilkins@google.com,debargha@google.com,builds@webmproject.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: Ic9849e4e0db64e9d92bbb9df9cc923230a15c4df

2 files changed, 11 insertions, 16 deletions

diff --git a/vp9/encoder/vp9_ratectrl.c b/vp9/encoder/vp9_ratectrl.c
index 4e2fc3e3f..70613c9eb 100644
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -47,6 +47,8 @@
 #define MIN_BPB_FACTOR 0.005
 #define MAX_BPB_FACTOR 50
 
+#define FRAME_OVERHEAD_BITS 200
+
 #if CONFIG_VP9_HIGHBITDEPTH
 #define ASSIGN_MINQ_TABLE(bit_depth, name)       \
   do {                                           \
@@ -210,23 +212,18 @@ int vp9_estimate_bits_at_q(FRAME_TYPE frame_type, int q, int mbs,
 int vp9_rc_clamp_pframe_target_size(const VP9_COMP *const cpi, int target) {
   const RATE_CONTROL *rc = &cpi->rc;
   const VP9EncoderConfig *oxcf = &cpi->oxcf;
-
-  if (cpi->oxcf.pass != 2) {
-    const int min_frame_target =
-        VPXMAX(rc->min_frame_bandwidth, rc->avg_frame_bandwidth >> 5);
-    if (target < min_frame_target) target = min_frame_target;
-    if (cpi->refresh_golden_frame && rc->is_src_frame_alt_ref) {
-      // If there is an active ARF at this location use the minimum
-      // bits on this frame even if it is a constructed arf.
-      // The active maximum quantizer insures that an appropriate
-      // number of bits will be spent if needed for constructed ARFs.
-      target = min_frame_target;
-    }
+  const int min_frame_target =
+      VPXMAX(rc->min_frame_bandwidth, rc->avg_frame_bandwidth >> 5);
+  if (target < min_frame_target) target = min_frame_target;
+  if (cpi->refresh_golden_frame && rc->is_src_frame_alt_ref) {
+    // If there is an active ARF at this location use the minimum
+    // bits on this frame even if it is a constructed arf.
+    // The active maximum quantizer insures that an appropriate
+    // number of bits will be spent if needed for constructed ARFs.
+    target = min_frame_target;
   }
-
   // Clip the frame target to the maximum allowed value.
   if (target > rc->max_frame_bandwidth) target = rc->max_frame_bandwidth;
-
   if (oxcf->rc_max_inter_bitrate_pct) {
     const int max_rate =
         rc->avg_frame_bandwidth * oxcf->rc_max_inter_bitrate_pct / 100;
diff --git a/vp9/encoder/vp9_ratectrl.h b/vp9/encoder/vp9_ratectrl.h
index cf37117f9..87b1ec33e 100644
--- a/vp9/encoder/vp9_ratectrl.h
+++ b/vp9/encoder/vp9_ratectrl.h
@@ -32,8 +32,6 @@ extern "C" {
 #define FIXED_GF_INTERVAL 8  // Used in some testing modes only
 #define ONEHALFONLY_RESIZE 0
 
-#define FRAME_OVERHEAD_BITS 200
-
 // Threshold used to define a KF group as static (e.g. a slide show).
 // Essentially this means that no frame in the group has more than 1% of MBs
 // that are not marked as coded with 0,0 motion in the first pass.