Revert "Improved 1-pass CBR rate control"

This reverts commit b5ea2fbc. Further
testing showed noticable keyframe popping in some cases, reverting this
for now to give time for a proper fix.

Conflicts:

	vp8/encoder/onyx_if.c
	vp8/encoder/ratectrl.c

Change-Id: I159f53d1bf0e24c035754ab3ded8ccfd58fd04af

vp8/common/onyxd.h

@@ -18,7 +18,6 @@
 extern "C"
 {
 #endif
-#include "vpx/vpx_codec.h"
 #include "type_aliases.h"
 #include "vpx_scale/yv12config.h"
 #include "ppflags.h"

vp8/encoder/firstpass.c

@@ -357,58 +357,33 @@ static int frame_max_bits(VP8_COMP *cpi)
     int max_bits;
 
     // For CBR we need to also consider buffer fullness.
+    // If we are running below the optimal level then we need to gradually tighten up on max_bits.
     if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
     {
-        max_bits = 2 * cpi->av_per_frame_bandwidth;
-        max_bits -= cpi->buffered_av_per_frame_bandwidth;
-        max_bits *= ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0);
-    }
-    // VBR
-    else
-    {
-        // For VBR base this on the bits and frames left plus the two_pass_vbrmax_section rate passed in by the user
-        max_bits = (int)(((double)cpi->twopass.bits_left / (cpi->twopass.total_stats->count - (double)cpi->common.current_video_frame)) * ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
-    }
-
-    // Trap case where we are out of bits
-    if (max_bits < 0)
-        max_bits = 0;
+        double buffer_fullness_ratio = (double)cpi->buffer_level / DOUBLE_DIVIDE_CHECK((double)cpi->oxcf.optimal_buffer_level);
 
-    return max_bits;
-}
+        // For CBR base this on the target average bits per frame plus the maximum sedction rate passed in by the user
+        max_bits = (int)(cpi->av_per_frame_bandwidth * ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
 
+        // If our buffer is below the optimum level
+        if (buffer_fullness_ratio < 1.0)
+        {
+            // The lower of max_bits / 4 or cpi->av_per_frame_bandwidth / 4.
+            int min_max_bits = ((cpi->av_per_frame_bandwidth >> 2) < (max_bits >> 2)) ? cpi->av_per_frame_bandwidth >> 2 : max_bits >> 2;
 
-static int gf_group_max_bits(VP8_COMP *cpi)
-{
-    // Max allocation for a golden frame group
-    int max_bits;
+            max_bits = (int)(max_bits * buffer_fullness_ratio);
 
-    // For CBR we need to also consider buffer fullness.
-    if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
-    {
-        max_bits = cpi->av_per_frame_bandwidth * cpi->baseline_gf_interval;
-        if (max_bits > cpi->oxcf.optimal_buffer_level)
-        {
-            max_bits -= cpi->oxcf.optimal_buffer_level;
-            max_bits += cpi->buffer_level;
+            if (max_bits < min_max_bits)
+                max_bits = min_max_bits;       // Lowest value we will set ... which should allow the buffer to refil.
         }
-        else
-        {
-            max_bits -= (cpi->buffered_av_per_frame_bandwidth
-                         - cpi->av_per_frame_bandwidth)
-                        * cpi->baseline_gf_interval;
-        }
-
-        max_bits *= ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0);
     }
+    // VBR
     else
     {
         // For VBR base this on the bits and frames left plus the two_pass_vbrmax_section rate passed in by the user
         max_bits = (int)(((double)cpi->twopass.bits_left / (cpi->twopass.total_stats->count - (double)cpi->common.current_video_frame)) * ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
-        max_bits *=  cpi->baseline_gf_interval;
     }
 
-
     // Trap case where we are out of bits
     if (max_bits < 0)
         max_bits = 0;
@@ -1626,7 +1601,7 @@ static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
     double abs_mv_in_out_accumulator = 0.0;
     double mod_err_per_mb_accumulator = 0.0;
 
-    int max_group_bits;
+    int max_bits = frame_max_bits(cpi);     // Max for a single frame
 
     unsigned int allow_alt_ref =
                     cpi->oxcf.play_alternate && cpi->oxcf.lag_in_frames;
@@ -1988,9 +1963,8 @@ static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
 
     // Clip cpi->twopass.gf_group_bits based on user supplied data rate
     // variability limit (cpi->oxcf.two_pass_vbrmax_section)
-    max_group_bits = gf_group_max_bits(cpi);
-    if (cpi->twopass.gf_group_bits > max_group_bits)
-        cpi->twopass.gf_group_bits = max_group_bits;
+    if (cpi->twopass.gf_group_bits > max_bits * cpi->baseline_gf_interval)
+        cpi->twopass.gf_group_bits = max_bits * cpi->baseline_gf_interval;
 
     // Reset the file position
     reset_fpf_position(cpi, start_pos);
@@ -2090,6 +2064,13 @@ static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
             }
         }
 
+        // Apply an additional limit for CBR
+        if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+        {
+            if (cpi->twopass.gf_bits > (cpi->buffer_level >> 1))
+                cpi->twopass.gf_bits = cpi->buffer_level >> 1;
+        }
+
         // Dont allow a negative value for gf_bits
         if (gf_bits < 0)
             gf_bits = 0;

vp8/encoder/onyx_if.c

@@ -1460,7 +1460,6 @@ static void init_config(VP8_PTR ptr, VP8_CONFIG *oxcf)
     cpi->rolling_actual_bits          = cpi->av_per_frame_bandwidth;
     cpi->long_rolling_target_bits     = cpi->av_per_frame_bandwidth;
     cpi->long_rolling_actual_bits     = cpi->av_per_frame_bandwidth;
-    cpi->buffered_av_per_frame_bandwidth = cpi->av_per_frame_bandwidth;
 
     cpi->total_actual_bits            = 0;
     cpi->total_target_vs_actual       = 0;
@@ -1556,7 +1555,7 @@ void vp8_change_config(VP8_PTR ptr, VP8_CONFIG *oxcf)
         break;
     }
 
-    if (cpi->pass == 0 && cpi->oxcf.end_usage != USAGE_STREAM_FROM_SERVER)
+    if (cpi->pass == 0)
         cpi->auto_worst_q = 1;
 
     cpi->oxcf.worst_allowed_q = q_trans[oxcf->worst_allowed_q];
@@ -3198,116 +3197,6 @@ void loopfilter_frame(VP8_COMP *cpi, VP8_COMMON *cm)
 
 }
 
-
-static void update_buffer_level(VP8_COMP *cpi)
-{
-    int64_t tmp;
-
-    /* Update the buffered average bitrate.
-     *
-     * The buffered average bitrate tracks the bitrate over the buffer
-     * window. Here we simulate taking a frame of average size out
-     * of the buffer, and putting in the new frame just encoded.
-     * It is calculated accordingly:
-     *
-     * A = Average Bits Per Frame In The Buffer
-     * P = New Frame Size
-     * N = Number of bits in the buffer
-     *
-     * We recalculate the average as so:
-     *      (N-A)*A + A*P    A * (N - A + P)
-     * A' = ------------- =  ---------------
-     *            N                 N
-     *
-     * This is modeled after a the standard algorithm for a moving
-     * average with fixed weighting (eg A' = ((N-1)*A + 1*P) / N). This makes
-     * the step response nonlinear but consistent with expected behavior --
-     * when A is large, the model adapts more quickly, since there are
-     * fewer frames in the buffer and conversely when A is small there
-     * will be more frames in the buffer so the average will adapt
-     * slowly.
-     *
-     * TODO(jkoleszar): This may give poor step response in some situations,
-     * for example motion following a long static section. It might be
-     * worth experimenting more with weighting by av_per_frame_bandwidth
-     * rather than buffered_av_per_frame_bandwidth or using a more accurate
-     * algorithm to get faster response. Current testing showed worse results
-     * with that setting though.
-     *
-     */
-
-    /* Guard against buffered_av_per_frame_bandwidth falling to 0. Should
-     * never happen, but without this check, it would be irrecoverable.
-     */
-    if(cpi->buffered_av_per_frame_bandwidth == 0)
-        cpi->buffered_av_per_frame_bandwidth = 1;
-
-    tmp = cpi->oxcf.maximum_buffer_size
-                - cpi->buffered_av_per_frame_bandwidth
-                + cpi->projected_frame_size;
-    tmp *= cpi->buffered_av_per_frame_bandwidth;
-    cpi->buffered_av_per_frame_bandwidth = tmp
-                                           / cpi->oxcf.maximum_buffer_size;
-
-    if(cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
-    {
-        /* In CBR mode, buffer level is synthesized from the buffered
-         * average per-frame bandwidth to get the response characteristics
-         * of that model, rather than using the unbounded (wrt buffer size)
-         * bits_off_target. ie, the long term average bitrate doesn't
-         * matter in CBR mode. If the clip is consistently undershooting
-         * because it is very static, for example, you don't want to blow
-         * your short term bitrate budget trying to the the long term spend
-         * up to the target when you hit a motion section.
-         *
-         * Instead, the ratio of buffered_av_per_frame_bandwidth to the
-         * target av_per_frame_bandwidth is taken, scaled by
-         * maximum_buffer_size and centered around optimal_buffer_level,
-         * which presents the expected behavior of buffer_level for the other
-         * parts of the rate control code which handle the targeting.
-         *
-         * Note that this only happens after the starting_buffer_level
-         * has passed, to give the model a chance to stabilize.
-         */
-        if(cpi->total_actual_bits > cpi->oxcf.starting_buffer_level)
-        {
-            tmp = (int64_t)cpi->buffered_av_per_frame_bandwidth
-                  * cpi->oxcf.maximum_buffer_size
-                  / cpi->av_per_frame_bandwidth;
-            cpi->buffer_level = cpi->oxcf.maximum_buffer_size
-                                - tmp
-                                + cpi->oxcf.optimal_buffer_level;
-        }
-        else
-            cpi->buffer_level = cpi->oxcf.optimal_buffer_level;
-
-        /* Accumulate recent overshoot error.
-         *
-         * If this frame is larger than the target, then accumulate
-         * that error to apply as a damping factor later. Only care about
-         * recent overshoot, so this value decays by (N-P)/N
-         */
-        if(cpi->total_actual_bits > cpi->oxcf.starting_buffer_level)
-        {
-            int64_t decayed_overshoot;
-
-            decayed_overshoot = cpi->accumulated_overshoot;
-            decayed_overshoot *= (cpi->oxcf.maximum_buffer_size
-                                  - cpi->projected_frame_size);
-            decayed_overshoot /= cpi->oxcf.maximum_buffer_size;
-            cpi->accumulated_overshoot = decayed_overshoot;
-
-            cpi->accumulated_overshoot +=
-                (cpi->projected_frame_size > cpi->av_per_frame_bandwidth)
-                ? cpi->projected_frame_size - cpi->av_per_frame_bandwidth
-                : 0;
-        }
-    }
-    else
-        cpi->buffer_level = cpi->bits_off_target;
-}
-
-
 static void encode_frame_to_data_rate
 (
     VP8_COMP *cpi,
@@ -3553,8 +3442,7 @@ static void encode_frame_to_data_rate
     // For CBR if the buffer reaches its maximum level then we can no longer
     // save up bits for later frames so we might as well use them up
     // on the current frame.
-    if (cpi->pass == 2
-        && (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) &&
+    if ((cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) &&
         (cpi->buffer_level >= cpi->oxcf.optimal_buffer_level) && cpi->buffered_mode)
     {
         int Adjustment = cpi->active_worst_quality / 4;       // Max adjustment is 1/4
@@ -3645,10 +3533,6 @@ static void encode_frame_to_data_rate
         }
         else
         {
-            if(cpi->pass != 2)
-                Q = cpi->auto_worst_q?
-                    cpi->active_worst_quality:cpi->avg_frame_qindex;
-
             cpi->active_best_quality = inter_minq[Q];
 
             // For the constant/constrained quality mode we dont want
@@ -3950,17 +3834,15 @@ static void encode_frame_to_data_rate
             (cpi->active_worst_quality < cpi->worst_quality)      &&
             (cpi->projected_frame_size > frame_over_shoot_limit))
         {
-            /* step down active_worst_quality such that the corresponding
-             * active_best_quality will be equal to the current
-             * active_worst_quality + 1. Once the limit on active_best_quality
-             * is reached, active_worst_quality will equal worst_quality.
-             */
-            int i;
+            int over_size_percent = ((cpi->projected_frame_size - frame_over_shoot_limit) * 100) / frame_over_shoot_limit;
 
-            for(i=cpi->active_worst_quality; i<cpi->worst_quality; i++)
-                if(inter_minq[i] >= cpi->active_worst_quality + 1)
-                    break;
-            cpi->active_worst_quality = i;
+            // If so is there any scope for relaxing it
+            while ((cpi->active_worst_quality < cpi->worst_quality) && (over_size_percent > 0))
+            {
+                cpi->active_worst_quality++;
+                top_index = cpi->active_worst_quality;
+                over_size_percent = (int)(over_size_percent * 0.96);        // Assume 1 qstep = about 4% on frame size.
+            }
 
             // If we have updated the active max Q do not call vp8_update_rate_correction_factors() this loop.
             active_worst_qchanged = TRUE;
@@ -4348,9 +4230,10 @@ static void encode_frame_to_data_rate
 
     // Update the buffer level variable.
     // Non-viewable frames are a special case and are treated as pure overhead.
-    if ( cm->show_frame )
-        cpi->bits_off_target += cpi->av_per_frame_bandwidth;
-    cpi->bits_off_target -= cpi->projected_frame_size;
+    if ( !cm->show_frame )
+        cpi->bits_off_target -= cpi->projected_frame_size;
+    else
+        cpi->bits_off_target += cpi->av_per_frame_bandwidth - cpi->projected_frame_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;
@@ -4364,7 +4247,7 @@ static void encode_frame_to_data_rate
     // Debug stats
     cpi->total_target_vs_actual += (cpi->this_frame_target - cpi->projected_frame_size);
 
-    update_buffer_level(cpi);
+    cpi->buffer_level = cpi->bits_off_target;
 
     // Update bits left to the kf and gf groups to account for overshoot or undershoot on these frames
     if (cm->frame_type == KEY_FRAME)

vp8/encoder/onyx_int.h

@@ -348,10 +348,6 @@ typedef struct VP8_COMP
     int per_frame_bandwidth;          // Current section per frame bandwidth target
     int av_per_frame_bandwidth;        // Average frame size target for clip
     int min_frame_bandwidth;          // Minimum allocation that should be used for any frame
-    int buffered_av_per_frame_bandwidth; // Average bitrate over the last buffer
-    int buffered_av_per_frame_bandwidth_rem; // Average bitrate remainder
-    int accumulated_overshoot;           // Accumulated # of bits spent > target
-
     int inter_frame_target;
     double output_frame_rate;
     int64_t last_time_stamp_seen;

vp8/encoder/ratectrl.c

@@ -608,7 +608,7 @@ static void calc_pframe_target_size(VP8_COMP *cpi)
     int min_frame_target;
     int Adjustment;
 
-    min_frame_target = 1;
+    min_frame_target = 0;
 
     if (cpi->pass == 2)
     {
@@ -617,11 +617,9 @@ static void calc_pframe_target_size(VP8_COMP *cpi)
         if (min_frame_target < (cpi->av_per_frame_bandwidth >> 5))
             min_frame_target = cpi->av_per_frame_bandwidth >> 5;
     }
-    else
-    {
-        if (min_frame_target < cpi->per_frame_bandwidth / 4)
-            min_frame_target = cpi->per_frame_bandwidth / 4;
-    }
+    else if (min_frame_target < cpi->per_frame_bandwidth / 4)
+        min_frame_target = cpi->per_frame_bandwidth / 4;
+
 
     // Special alt reference frame case
     if (cpi->common.refresh_alt_ref_frame)
@@ -1114,33 +1112,6 @@ static void calc_pframe_target_size(VP8_COMP *cpi)
 
         }
     }
-
-    if (cpi->pass==0
-        && cpi->common.refresh_golden_frame
-        && cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) {
-        int64_t adjust;
-
-        /*
-        frames_in_buffer = cpi->oxcf.maximum_buffer_size
-                           / cpi->av_per_frame_bandwidth;
-        gf_in_buffer = frames_in_buffer /
-                       cpi->frames_till_gf_update_due;
-        overshoot_per_gf = cpi->accumulated_overshoot / gf_in_buffer;
-
-        */
-
-        adjust = cpi->accumulated_overshoot;
-        adjust *= cpi->frames_till_gf_update_due + 1;
-        adjust *= cpi->av_per_frame_bandwidth;
-        adjust /= cpi->oxcf.maximum_buffer_size;
-
-        if (adjust > (cpi->this_frame_target - min_frame_target))
-            adjust = (cpi->this_frame_target - min_frame_target);
-        else if (adjust < 0)
-            adjust = 0;
-
-        cpi->this_frame_target -= adjust;
-    }
 }