whisper : improve beam search candidate diversity

whisper.cpp

@@ -4759,6 +4759,19 @@ static void whisper_process_logits(
 #endif
 }
 
+static bool whisper_sequence_tokens_equal(const whisper_sequence & a, const whisper_sequence & b) {
+ if (a.tokens.size() != b.tokens.size()) {
+ return false;
+ }
+ // sequences are more likely to diverge at the end
+ for (int i = a.tokens.size() - 1; i >= 0; i--) {
+ if (a.tokens[i].id != b.tokens[i].id) {
+ return false;
+ }
+ }
+ return true;
+}
+
 static whisper_token_data whisper_sample_token(
  whisper_context & ctx,
  const whisper_decoder & decoder,
@@ -5378,7 +5391,7 @@ int whisper_full_with_state(
 
  auto & cur = beam_candidates[cur_c++];
 
- while (beam_candidates.size() > cur_c && beam_candidates[cur_c].sequence.sum_logprobs_all == cur.sequence.sum_logprobs_all && i > 0) {
+ while (beam_candidates.size() > cur_c && whisper_sequence_tokens_equal(beam_candidates[cur_c].sequence, cur.sequence) && i > 0) {
  ++cur_c;
  }