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manually fix up comments in libs/timecode/src/time.cc that got edited by f2s

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This commit is contained in:
Paul Davis 2017-09-18 13:19:12 -04:00
parent 30b087ab3d
commit 7a477fb9d6
1 changed files with 20 additions and 20 deletions
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libs/timecode/src/time.cc
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@ -274,7 +274,7 @@ decrement_subframes (Time& timecode, uint32_t subframes_per_frame)
} }
/** Go to next whole second (samples == 0 or samples == 2) */ /** Go to next whole second (frames == 0 or frames == 2) */
Wrap Wrap
increment_seconds (Time& timecode, uint32_t subframes_per_frame) increment_seconds (Time& timecode, uint32_t subframes_per_frame)
{ {
@ -286,13 +286,13 @@ increment_seconds (Time& timecode, uint32_t subframes_per_frame)
if (timecode.negative) { if (timecode.negative) {
// Wrap second if on second boundary // Wrap second if on second boundary
wrap = increment (timecode, subframes_per_frame); wrap = increment (timecode, subframes_per_frame);
// Go to lowest absolute sample value // Go to lowest absolute frame value
seconds_floor (timecode); seconds_floor (timecode);
if (Timecode_IS_ZERO (timecode)) { if (Timecode_IS_ZERO (timecode)) {
timecode.negative = false; timecode.negative = false;
} }
} else { } else {
// Go to highest possible sample in this second // Go to highest possible frame in this second
switch ((int)ceil (timecode.rate)) { switch ((int)ceil (timecode.rate)) {
case 24: case 24:
timecode.frames = 23; timecode.frames = 23;
@ -308,7 +308,7 @@ increment_seconds (Time& timecode, uint32_t subframes_per_frame)
break; break;
} }
// Increment by one sample // Increment by one frame
wrap = increment (timecode, subframes_per_frame); wrap = increment (timecode, subframes_per_frame);
} }
@ -316,7 +316,7 @@ increment_seconds (Time& timecode, uint32_t subframes_per_frame)
} }
/** Go to lowest (absolute) sample value in this second /** Go to lowest (absolute) frame value in this second
* Doesn't care about positive/negative */ * Doesn't care about positive/negative */
void void
seconds_floor (Time& timecode) seconds_floor (Time& timecode)
@ -324,7 +324,7 @@ seconds_floor (Time& timecode)
// Clear subframes // Clear subframes
frames_floot (timecode); frames_floot (timecode);
// Go to lowest possible sample in this second // Go to lowest possible frame in this second
switch ((int)ceil (timecode.rate)) { switch ((int)ceil (timecode.rate)) {
case 24: case 24:
case 25: case 25:
@ -348,7 +348,7 @@ seconds_floor (Time& timecode)
} }
/** Go to next whole minute (seconds == 0, samples == 0 or samples == 2) */ /** Go to next whole minute (seconds == 0, frames == 0 or frames == 2) */
Wrap Wrap
increment_minutes (Time& timecode, uint32_t subframes_per_frame) increment_minutes (Time& timecode, uint32_t subframes_per_frame)
{ {
@ -379,7 +379,7 @@ minutes_floor (Time& timecode)
{ {
// Go to lowest possible second // Go to lowest possible second
timecode.seconds = 0; timecode.seconds = 0;
// Go to lowest possible sample // Go to lowest possible frame
seconds_floor (timecode); seconds_floor (timecode);
if (Timecode_IS_ZERO (timecode)) { if (Timecode_IS_ZERO (timecode)) {
@ -388,7 +388,7 @@ minutes_floor (Time& timecode)
} }
/** Go to next whole hour (minute = 0, second = 0, sample = 0) */ /** Go to next whole hour (minute = 0, second = 0, frame = 0) */
Wrap Wrap
increment_hours (Time& timecode, uint32_t subframes_per_frame) increment_hours (Time& timecode, uint32_t subframes_per_frame)
{ {
@ -656,21 +656,21 @@ timecode_to_sample(
const double samples_per_timecode_frame = (double) sample_sample_rate / (double) timecode.rate; const double samples_per_timecode_frame = (double) sample_sample_rate / (double) timecode.rate;
if (timecode.drop) { if (timecode.drop) {
// The drop sample format was created to better approximate the 30000/1001 = 29.97002997002997.... // The drop frame format was created to better approximate the 30000/1001 = 29.97002997002997....
// framerate of NTSC color TV. The used frame rate of drop sample is 29.97, which drifts by about // framerate of NTSC color TV. The used frame rate of drop fra,e is 29.97, which drifts by about
// 0.108 sample per hour, or about 1.3 samples per 12 hours. This is not perfect, but a lot better // 0.108 frame per hour, or about 1.3 frames per 12 hours. This is not perfect, but a lot better
// than using 30 non drop, which will drift with about 1.8 sample per minute. // than using 30 non drop, which will drift with about 1.8 frame per minute.
// Using 29.97, drop sample real time can be accurate only every 10th minute (10 minutes of 29.97 fps // Using 29.97, drop frame real time can be accurate only every 10th minute (10 minutes of 29.97 fps
// is exactly 17982 samples). One minute is 1798.2 samples, but we count 30 samples per second // is exactly 17982 samples). One minute is 1798.2 samples, but we count 30 frames per second
// (30 * 60 = 1800). This means that at the first minute boundary (at the end of 0:0:59:29) we // (30 * 60 = 1800). This means that at the first minute boundary (at the end of 0:0:59:29) we
// are 1.8 samples too late relative to real time. By dropping 2 samples (jumping to 0:1:0:2) we are // are 1.8 framess too late relative to real time. By dropping 2 frames (jumping to 0:1:0:2) we are
// approx. 0.2 samples too early. This adds up with 0.2 too early for each minute until we are 1.8 // approx. 0.2 frames too early. This adds up with 0.2 too early for each minute until we are 1.8
// samples too early at 0:9:0:2 (9 * 0.2 = 1.8). The 10th minute brings us 1.8 samples later again // samples too early at 0:9:0:2 (9 * 0.2 = 1.8). The 10th minute brings us 1.8 frames later again
// (at end of 0:9:59:29), which sums up to 0 (we are back to zero at 0:10:0:0 :-). // (at end of 0:9:59:29), which sums up to 0 (we are back to zero at 0:10:0:0 :-).
// //
// In table form: // In table form:
// //
// Timecode value samples offset subframes offset seconds (rounded) 44100 sample (rounded) // Timecode value frames offset subframes offset seconds (rounded) 44100 sample (rounded)
// 0:00:00:00 0.0 0 0.000 0 (accurate) // 0:00:00:00 0.0 0 0.000 0 (accurate)
// 0:00:59:29 1.8 144 60.027 2647177 // 0:00:59:29 1.8 144 60.027 2647177
// 0:01:00:02 -0.2 -16 60.060 2648648 // 0:01:00:02 -0.2 -16 60.060 2648648
@ -712,7 +712,7 @@ timecode_to_sample(
/* /*
Non drop is easy.. just note the use of Non drop is easy.. just note the use of
rint(timecode.rate) * samples_per_timecode_frame rint(timecode.rate) * samples_per_timecode_frame
(samples per Timecode second), which is larger than (frames per Timecode second), which is larger than
sample_rate() in the non-integer Timecode rate case. sample_rate() in the non-integer Timecode rate case.
*/ */