decoder/vorbis: faster tag scanning with ov_test_callback()

using ov_test_callback with function CALLBACKS_STREAMONLY will cause scanning to stop after the comment field. ov_open (and ov_test) default to CALLBACKS_DEFAULT which scans the file structure causing a huge slowdown. The speed improvement is huge: It scanned my files around 10x faster This procedure has been recommended by monthy (main vorbis developer) and was said to be safe for scanning files.

decoder/vorbis: faster tag scanning with ov_test_callback()
408f7237 · Rasmus Steinke · Max Kellermann · 9d42f4e0 · 408f7237 · 408f7237
Commit 408f7237 authored Aug 24, 2009 by Rasmus Steinke Committed by Max Kellermann Aug 24, 2009
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NEWS NEWS +2 -0

vorbis_plugin.c src/decoder/vorbis_plugin.c +1 -1

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--- a/NEWS
+++ b/NEWS
 ver 0.15.3 (2009/??/??)
+* decoders:
+  - vorbis: faster tag scanning with ov_test_callback()
 * output:
  - fix stuttering due to uninitialized variable
 * update: don't re-read unchanged container files

--- a/src/decoder/vorbis_plugin.c
+++ b/src/decoder/vorbis_plugin.c
@@ -383,7 +383,7 @@ vorbis_tag_dup(const char *file)
 		return NULL;
 	}

-	if (ov_open(fp, &vf, NULL, 0) < 0) {
+	if (ov_test_callbacks(fp, &vf, NULL, 0, OV_CALLBACKS_STREAMONLY) < 0) {
 		fclose(fp);
 		return NULL;
 	}