Implement level's bitrate limit checking during encoding

src/cfg.c

@@ -1252,7 +1252,8 @@ void kvz_config_process_lp_gop(kvz_config *cfg)
   cfg->gop[gop.g - 1].qp_factor = 0.578;  // from HM
 }
 
-static int validate_hevc_level(const kvz_config *const cfg);
+// forward declaration
+static int validate_hevc_level(kvz_config *const cfg);
 
 /**
  * \brief Check that configuration is sensible.
@@ -1460,7 +1461,7 @@ int kvz_config_validate(const kvz_config *const cfg)
   return !error;
 }
 
-static int validate_hevc_level(const kvz_config *const cfg) {
+static int validate_hevc_level(kvz_config *const cfg) {
   static const struct { uint32_t lsr; uint32_t lps; uint32_t main_bitrate; } LEVEL_CONSTRAINTS[13] = {
     { 552'960, 36'864, 128 }, // 1
 
@@ -1559,17 +1560,15 @@ static int validate_hevc_level(const kvz_config *const cfg) {
   // max luma picture size
   uint32_t max_lps = LEVEL_CONSTRAINTS[lvl_idx].lps;
 
-  // max bitrate
-  uint32_t max_bitrate;
   if (cfg->high_tier) {
-    max_bitrate = HIGH_TIER_BITRATES[lvl_idx - 5] * 1000;
+    cfg->max_bitrate = HIGH_TIER_BITRATES[lvl_idx - 5] * 1000;
   } else {
-    max_bitrate = LEVEL_CONSTRAINTS[lvl_idx].main_bitrate * 1000;
+    cfg->max_bitrate = LEVEL_CONSTRAINTS[lvl_idx].main_bitrate * 1000;
   }
 
-  if (cfg->target_bitrate > max_bitrate) {
+  if (cfg->target_bitrate > cfg->max_bitrate) {
     fprintf(stderr, "%s: target bitrate exceeds %i, which is the maximum %s tier level %g bitrate\n",
-      level_err_prefix, max_bitrate, cfg->high_tier?"high":"main", lvl);
+      level_err_prefix, cfg->max_bitrate, cfg->high_tier?"high":"main", lvl);
     level_error = 1;
   }
 
@@ -1614,7 +1613,7 @@ static int validate_hevc_level(const kvz_config *const cfg) {
   }
 
   if (cfg->force_level) {
-    // we just wanted to print warnings, and to check the level parameter's validity
+    // we wanted to print warnings, not get errors
     return 0;
   } else {
     return level_error;

src/cfg.h

@@ -30,7 +30,6 @@
 
 #include "kvazaar.h"
 
-
 /* Function definitions */
 kvz_config *kvz_config_alloc(void);
 int kvz_config_init(kvz_config *cfg);

src/encmain.c

@@ -431,6 +431,12 @@ int main(int argc, char *argv[])
     uint32_t frames_done = 0;
     double psnr_sum[3] = { 0.0, 0.0, 0.0 };
 
+    // how many bits have been written this second? used for checking if framerate exceeds level's limits
+    uint64_t bits_this_second = 0;
+    // the amount of frames have been encoded in this second of video. can be non-integer value if framerate is non-integer value
+    float frames_this_second = 0;
+    float framerate = ((float)encoder->cfg.framerate_num) / ((float)encoder->cfg.framerate_denom);
+
     uint8_t padding_x = get_padding(opts->config->width);
     uint8_t padding_y = get_padding(opts->config->height);
 
@@ -527,6 +533,18 @@ int main(int argc, char *argv[])
         fflush(output);
 
         bitstream_length += len_out;
+        
+        // the level's bitrate check
+        bits_this_second += len_out;
+        frames_this_second += 1.0f;
+
+        if (frames_this_second >= framerate) {
+          if (bits_this_second > encoder->cfg.max_bitrate) {
+            fprintf(stderr, "Level warning: This second's bitrate (%llu) reached the maximum bitrate (%u) of %s tier level %g.",
+              bits_this_second, encoder->cfg.max_bitrate, encoder->cfg.high_tier?"high":"main", ((float)encoder->cfg.level) / 10.0f);
+          }
+          frames_this_second -= framerate;
+        }
 
         // Compute and print stats.
 

src/kvazaar.h

@@ -358,6 +358,8 @@ typedef struct kvz_config
   uint8_t force_level;
   /** \brief Whether we use the high tier bitrates. Requires the level to be 4 or higher. */
   uint8_t high_tier;
+  /** \brief The maximum allowed bitrate for this level and tier. */
+  uint32_t max_bitrate;
 } kvz_config;
 
 /**