From d444fa7db996a3ee20c1364559e9518c07548ba8 Mon Sep 17 00:00:00 2001
From: Wohlstand <admin@wohlnet.ru>
Date: Fri, 18 Feb 2022 22:55:50 +0300
Subject: [PATCH] stb_vorbis: report the sample-accurate offset

Added the `stb_vorbis_get_playback_sample_offset()` call that reports the sample-accurate position which is required for several operations such as loop range processing.
---
 stb_vorbis.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/stb_vorbis.c b/stb_vorbis.c
index 3e5c2504c0..3b332b4f5c 100644
--- a/stb_vorbis.c
+++ b/stb_vorbis.c
@@ -21,6 +21,7 @@
 //
 // Feature contributors:
 //    Dougall Johnson (sample-exact seeking)
+//    Vitaly Novichkov (sample-accurate tell)
 //
 // Bugfix/warning contributors:
 //    Terje Mathisen     Niklas Frykholm     Andy Hill
@@ -165,6 +166,12 @@ extern void stb_vorbis_close(stb_vorbis *f);
 // NOT WORKING YET after a seek with PULLDATA API
 extern int stb_vorbis_get_sample_offset(stb_vorbis *f);
 
+//  this function returns the count of returned samples from the beginning of the
+//  file. Functions "stb_vorbis_get_samples_*", "stb_vorbis_seek_*()" will
+//  affect the returned value. Use this call to get the accurate sample position
+//  during playback.
+extern int stb_vorbis_get_playback_sample_offset(stb_vorbis *f);
+
 // returns the current seek point within the file, or offset from the beginning
 // of the memory buffer. In pushdata mode it returns 0.
 extern unsigned int stb_vorbis_get_file_offset(stb_vorbis *f);
@@ -863,6 +870,9 @@ struct stb_vorbis
    uint32 current_loc; // sample location of next frame to decode
    int    current_loc_valid;
 
+   int32  current_playback_loc; // sample location of played samples
+   int    current_playback_loc_valid;
+
   // per-blocksize precomputed data
 
    // twiddle factors
@@ -3512,6 +3522,8 @@ static int vorbis_pump_first_frame(stb_vorbis *f)
    res = vorbis_decode_packet(f, &len, &left, &right);
    if (res)
       vorbis_finish_frame(f, len, left, right);
+   f->current_playback_loc = 0;
+   f->current_playback_loc_valid = TRUE;
    return res;
 }
 
@@ -4302,6 +4314,14 @@ int stb_vorbis_get_sample_offset(stb_vorbis *f)
       return -1;
 }
 
+int stb_vorbis_get_playback_sample_offset(stb_vorbis *f)
+{
+   if (f->current_playback_loc_valid)
+      return f->current_playback_loc;
+   else
+      return -1;
+}
+
 stb_vorbis_info stb_vorbis_get_info(stb_vorbis *f)
 {
    stb_vorbis_info d;
@@ -4913,13 +4933,16 @@ int stb_vorbis_seek_frame(stb_vorbis *f, unsigned int sample_number)
    }
    // the next frame should start with the sample
    if (f->current_loc != sample_number) return error(f, VORBIS_seek_failed);
+   f->current_playback_loc = sample_number;
    return 1;
 }
 
 int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number)
 {
-   if (!stb_vorbis_seek_frame(f, sample_number))
+   if (!stb_vorbis_seek_frame(f, sample_number)) {
+      f->current_playback_loc_valid = FALSE;
       return 0;
+   }
 
    if (sample_number != f->current_loc) {
       int n;
@@ -4930,6 +4953,9 @@ int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number)
       f->channel_buffer_start += (sample_number - frame_start);
    }
 
+   f->current_playback_loc_valid = TRUE;
+   f->current_playback_loc = sample_number;
+
    return 1;
 }
 
@@ -5322,6 +5348,7 @@ int stb_vorbis_get_samples_short_interleaved(stb_vorbis *f, int channels, short
       if (n == len) break;
       if (!stb_vorbis_get_frame_float(f, NULL, &outputs)) break;
    }
+   f->current_playback_loc += n;
    return n;
 }
 
@@ -5339,6 +5366,7 @@ int stb_vorbis_get_samples_short(stb_vorbis *f, int channels, short **buffer, in
       if (n == len) break;
       if (!stb_vorbis_get_frame_float(f, NULL, &outputs)) break;
    }
+   f->current_playback_loc += n;
    return n;
 }
 
@@ -5447,6 +5475,7 @@ int stb_vorbis_get_samples_float_interleaved(stb_vorbis *f, int channels, float
       if (!stb_vorbis_get_frame_float(f, NULL, &outputs))
          break;
    }
+   f->current_playback_loc += n;
    return n;
 }
 
@@ -5473,6 +5502,7 @@ int stb_vorbis_get_samples_float(stb_vorbis *f, int channels, float **buffer, in
       if (!stb_vorbis_get_frame_float(f, NULL, &outputs))
          break;
    }
+   f->current_playback_loc += n;
    return n;
 }
 #endif // STB_VORBIS_NO_PULLDATA_API