ReactOS  0.4.14-dev-390-g34947ad
gapless.h
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1 /*
2  sampleadjust: gapless sample offset math
3 
4  copyright 1995-2012 by the mpg123 project - free software under the terms of the LGPL 2.1
5  see COPYING and AUTHORS files in distribution or http://mpg123.org
6 
7  This is no stand-alone header, precisely to be able to fool it into using fake handle types for testing the math.
8 */
9 
10 #include "debug.h"
11 
12 #ifdef GAPLESS
13 /* From internal sample number to external. */
15 {
16  off_t s;
17  if(mh->p.flags & MPG123_GAPLESS)
18  {
19  /* It's a bit tricky to do this computation for the padding samples.
20  They are not there on the outside. */
21  if(x > mh->end_os)
22  {
23  if(x < mh->fullend_os)
24  s = mh->end_os - mh->begin_os;
25  else
26  s = x - (mh->fullend_os - mh->end_os + mh->begin_os);
27  }
28  else
29  s = x - mh->begin_os;
30  }
31  else
32  s = x;
33 
34  return s;
35 }
36 
37 /* from external samples to internal */
39 {
40  off_t s;
41  if(mh->p.flags & MPG123_GAPLESS)
42  {
43  s = x + mh->begin_os;
44  /* There is a hole; we don't create sample positions in there.
45  Jump from the end of the gapless track directly to after the padding. */
46  if(s >= mh->end_os)
47  s += mh->fullend_os - mh->end_os;
48  }
49  else s = x;
50 
51  return s;
52 }
53 
54 /*
55  Take the buffer after a frame decode (strictly: it is the data from frame fr->num!) and cut samples out.
56  fr->buffer.fill may then be smaller than before...
57 */
59 {
60  /* When we have no accurate position, gapless code does not make sense. */
61  if(!(fr->state_flags & FRAME_ACCURATE)) return;
62 
63  /* Get a grip on dirty streams that start with a gapless header.
64  Simply accept all data from frames that are too much,
65  they are supposedly attached to the stream after the fact. */
66  if(fr->gapless_frames > 0 && fr->num >= fr->gapless_frames) return;
67 
68  /* Important: We first cut samples from the end, then cut from beginning (including left-shift of the buffer).
69  This order works also for the case where firstframe == lastframe. */
70 
71  /* The last interesting (planned) frame: Only use some leading samples.
72  Note a difference from the below: The last frame and offset are unchanges by seeks.
73  The lastoff keeps being valid. */
74  if(fr->lastframe > -1 && fr->num >= fr->lastframe)
75  {
76  /* There can be more than one frame of padding at the end, so we ignore the whole frame if we are beyond lastframe. */
77  off_t byteoff = (fr->num == fr->lastframe) ? samples_to_bytes(fr, fr->lastoff) : 0;
78  if((off_t)fr->buffer.fill > byteoff)
79  {
80  fr->buffer.fill = byteoff;
81  }
82  if(VERBOSE3) fprintf(stderr, "\nNote: Cut frame %"OFF_P" buffer on end of stream to %"OFF_P" samples, fill now %"SIZE_P" bytes.\n", (off_p)fr->num, (off_p)(fr->num == fr->lastframe ? fr->lastoff : 0), (size_p)fr->buffer.fill);
83  }
84 
85  /* The first interesting frame: Skip some leading samples. */
86  if(fr->firstoff && fr->num == fr->firstframe)
87  {
88  off_t byteoff = samples_to_bytes(fr, fr->firstoff);
89  if((off_t)fr->buffer.fill > byteoff)
90  {
91  fr->buffer.fill -= byteoff;
92  /* buffer.p != buffer.data only for own buffer */
93  debug6("cutting %li samples/%li bytes on begin, own_buffer=%i at %p=%p, buf[1]=%i",
94  (long)fr->firstoff, (long)byteoff, fr->own_buffer, (void*)fr->buffer.p, (void*)fr->buffer.data, ((short*)fr->buffer.p)[2]);
95  if(fr->own_buffer) fr->buffer.p = fr->buffer.data + byteoff;
96  else memmove(fr->buffer.data, fr->buffer.data + byteoff, fr->buffer.fill);
97  debug3("done cutting, buffer at %p =? %p, buf[1]=%i",
98  (void*)fr->buffer.p, (void*)fr->buffer.data, ((short*)fr->buffer.p)[2]);
99  }
100  else fr->buffer.fill = 0;
101 
102  if(VERBOSE3) fprintf(stderr, "\nNote: Cut frame %"OFF_P" buffer on beginning of stream by %"OFF_P" samples, fill now %"SIZE_P" bytes.\n", (off_p)fr->num, (off_p)fr->firstoff, (size_p)fr->buffer.fill);
103  /* We can only reach this frame again by seeking. And on seeking, firstoff will be recomputed.
104  So it is safe to null it here (and it makes the if() decision abort earlier). */
105  fr->firstoff = 0;
106  }
107 }
108 
109 #define SAMPLE_ADJUST(mh,x) sample_adjust(mh,x)
110 #define SAMPLE_UNADJUST(mh,x) sample_unadjust(mh,x)
111 #define FRAME_BUFFERCHECK(mh) frame_buffercheck(mh)
112 
113 #else /* no gapless code included */
114 
115 #define SAMPLE_ADJUST(mh,x) (x)
116 #define SAMPLE_UNADJUST(mh,x) (x)
117 #define FRAME_BUFFERCHECK(mh)
118 
119 #endif
#define memmove(s1, s2, n)
Definition: mkisofs.h:881
struct mpg123_pars_struct p
Definition: frame.h:287
__kernel_off_t off_t
Definition: linux.h:201
struct outbuffer buffer
Definition: frame.h:265
GLint GLint GLint GLint GLint x
Definition: gl.h:1548
#define debug6(s, a, b, c, d, e, f)
Definition: debug.h:57
#define debug3(s, a, b, c)
Definition: debug.h:54
_Check_return_opt_ _CRTIMP int __cdecl fprintf(_Inout_ FILE *_File, _In_z_ _Printf_format_string_ const char *_Format,...)
#define VERBOSE3
off_t gapless_frames
Definition: frame.h:275
unsigned long size_p
Definition: compat.h:138
#define samples_to_bytes
Definition: intsym.h:217
static off_t sample_unadjust(mpg123_handle *mh, off_t x)
Definition: gapless.h:38
GLdouble s
Definition: gl.h:2039
#define SIZE_P
Definition: compat.h:137
long off_p
Definition: compat.h:130
FILE * stderr
static off_t sample_adjust(mpg123_handle *mh, off_t x)
Definition: gapless.h:14
#define OFF_P
Definition: compat.h:129
static void frame_buffercheck(mpg123_handle *fr)
Definition: gapless.h:58