CVBR command line option.

Added command line control of Corpus VBR.

The new corpus vbr mode is a variant of standard
VBR (end-usage=0) where the complexity distribution
mid point is passed in rather than calculated for a specific
clip or chunk.

The new variant is enabled by setting a new command line
parameter --corpus-complexity to a zero value. Omitting
this parameter or setting it to 0 will cause the codec to use
standard vbr mode.

The correct value for a given corpus needs to be derived
experimentally using a training set such that the average
rate for the corpus is close to the target value.

For example our using our low res test set with upper and lower
vbr limits of 50%-150% and a corpus complexity value of 650
gives a similar average data rate across the set to using standard
vbr. However, with the corpus mode easier clips will be allocated
fewer bits and harder clips more bits rather than having the same
rate target for all.

Change-Id: I03f0fc8c6fb0ee32dc03720fea6a3f1949118589

1 files changed, 11 insertions, 2 deletions

diff --git a/vpxenc.c b/vpxenc.c
index 845336a69..74c636ab7 100644
--- a/vpxenc.c
+++ b/vpxenc.c
@@ -321,8 +321,11 @@ static const arg_def_t minsection_pct =
     ARG_DEF(NULL, "minsection-pct", 1, "GOP min bitrate (% of target)");
 static const arg_def_t maxsection_pct =
     ARG_DEF(NULL, "maxsection-pct", 1, "GOP max bitrate (% of target)");
-static const arg_def_t *rc_twopass_args[] = { &bias_pct, &minsection_pct,
-                                              &maxsection_pct, NULL };
+static const arg_def_t corpus_complexity =
+    ARG_DEF(NULL, "corpus-complexity", 1, "corpus vbr complexity midpoint");
+static const arg_def_t *rc_twopass_args[] = {
+  &bias_pct, &minsection_pct, &maxsection_pct, &corpus_complexity, NULL
+};
 
 static const arg_def_t kf_min_dist =
     ARG_DEF(NULL, "kf-min-dist", 1, "Minimum keyframe interval (frames)");
@@ -1235,6 +1238,11 @@ static int parse_stream_params(struct VpxEncoderConfig *global,
 
       if (global->passes < 2)
         warn("option %s ignored in one-pass mode.\n", arg.name);
+    } else if (arg_match(&arg, &corpus_complexity, argi)) {
+      config->cfg.rc_2pass_vbr_corpus_complexity = arg_parse_uint(&arg);
+
+      if (global->passes < 2)
+        warn("option %s ignored in one-pass mode.\n", arg.name);
     } else if (arg_match(&arg, &kf_min_dist, argi)) {
       config->cfg.kf_min_dist = arg_parse_uint(&arg);
     } else if (arg_match(&arg, &kf_max_dist, argi)) {
@@ -1431,6 +1439,7 @@ static void show_stream_config(struct stream_state *stream,
   SHOW(rc_2pass_vbr_bias_pct);
   SHOW(rc_2pass_vbr_minsection_pct);
   SHOW(rc_2pass_vbr_maxsection_pct);
+  SHOW(rc_2pass_vbr_corpus_complexity);
   SHOW(kf_mode);
   SHOW(kf_min_dist);
   SHOW(kf_max_dist);