forked from mia/Aegisub
213 lines
8.1 KiB
C++
213 lines
8.1 KiB
C++
// Copyright (c) 2010, Thomas Goyne <plorkyeran@aegisub.org>
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//
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// Permission to use, copy, modify, and distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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/// @file vfr.h
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/// @brief Framerate handling of all sorts
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/// @ingroup libaegisub video_input
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#pragma once
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#include <string>
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#include <vector>
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#include <cstdint>
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#include <libaegisub/exception.h>
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#include <libaegisub/fs_fwd.h>
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namespace agi {
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/// Framerate handling.
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namespace vfr {
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enum Time {
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/// Use the actual frame times
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/// With 1 FPS video, frame 0 is [0, 999] ms
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EXACT,
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/// Calculate based on the rules for start times of lines
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/// Lines are first visible on the first frame with start time less than
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/// or equal to the start time; thus with 1.0 FPS video, frame 0 is
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/// [-999, 0] ms
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START,
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/// Calculate based on the rules for end times of lines
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/// Lines are last visible on the last frame with start time less than the
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/// end time; thus with 1.0 FPS video, frame 0 is [1, 1000] ms
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END
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};
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DEFINE_BASE_EXCEPTION_NOINNER(Error, Exception)
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/// FPS specified is not a valid frame rate
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DEFINE_SIMPLE_EXCEPTION_NOINNER(BadFPS, Error, "vfr/badfps")
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/// Unknown timecode file format
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DEFINE_SIMPLE_EXCEPTION_NOINNER(UnknownFormat, Error, "vfr/timecodes/unknownformat")
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/// Invalid line encountered in a timecode file
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DEFINE_SIMPLE_EXCEPTION_NOINNER(MalformedLine, Error, "vfr/timecodes/malformed")
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/// Timecode file or vector has too few timecodes to be usable
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DEFINE_SIMPLE_EXCEPTION_NOINNER(TooFewTimecodes, Error, "vfr/timecodes/toofew")
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/// Timecode file or vector has timecodes that are not monotonically increasing
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DEFINE_SIMPLE_EXCEPTION_NOINNER(UnorderedTimecodes, Error, "vfr/timecodes/order")
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/// @class Framerate
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/// @brief Class for managing everything related to converting frames to times
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/// or vice versa
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class Framerate {
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/// Denominator of the FPS
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///
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/// For v1 VFR, the assumed FPS is used, for v2 the average FPS
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int64_t denominator;
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/// Numerator of the FPS
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///
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/// For v1 VFR, the assumed FPS is used, for v2 the average FPS
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int64_t numerator;
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/// Unrounded frame-seconds of the final frame in timecodes. For CFR and v2,
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/// this is simply frame count * denominator, but for v1 it's the
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/// "unrounded" frame count, since override ranges generally don't exactly
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/// cover timebase-unit ranges of time. This is needed to match mkvmerge's
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/// rounding past the end of the final override range.
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int64_t last;
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/// Start time in milliseconds of each frame
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std::vector<int> timecodes;
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/// Does this frame rate need drop frames and have them enabled?
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bool drop;
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/// Set FPS properties from the timecodes vector
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void SetFromTimecodes();
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public:
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/// @brief VFR from timecodes file
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/// @param filename File with v1 or v2 timecodes
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///
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/// Note that loading a v1 timecode file with Assume X and no overrides is
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/// not the same thing as CFR X. When timecodes are loaded from a file,
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/// mkvmerge-style rounding is applied, while setting a constant frame rate
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/// uses truncation.
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Framerate(fs::path const& filename);
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/// @brief CFR constructor
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/// @param fps Frames per second or 0 for unloaded
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Framerate(double fps = 0.);
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/// @brief CFR constructor with rational timebase
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/// @param numerator Timebase numerator
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/// @param denominator Timebase denominator
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/// @param drop Enable drop frames if the FPS requires it
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Framerate(int64_t numerator, int64_t denominator, bool drop=true);
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/// @brief VFR from frame times
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/// @param timecodes Vector of frame start times in milliseconds
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Framerate(std::vector<int> const& timecodes);
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/// Helper function for the std::swap specialization
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void swap(Framerate &right) throw();
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/// @brief Get the frame visible at a given time
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/// @param ms Time in milliseconds
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/// @param type Time mode
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///
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/// When type is EXACT, the frame returned is the frame visible at the given
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/// time; when it is START or END it is the frame on which a line with that
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/// start/end time would first/last be visible
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int FrameAtTime(int ms, Time type = EXACT) const;
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/// @brief Get the time at a given frame
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/// @param frame Frame number
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/// @param type Time mode
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///
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/// When type is EXACT, the frame's exact start time is returned; START and
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/// END give a time somewhere within the range that will result in the line
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/// starting/ending on that frame
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///
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/// With v2 timecodes, frames outside the defined range are not an error
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/// and are guaranteed to be monotonically increasing/decreasing values
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/// which when passed to FrameAtTime will return the original frame; they
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/// are not guaranteed to be sensible or useful for any other purpose
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///
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/// v1 timecodes and CFR do not have a defined range, and will give sensible
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/// results for all frame numbers
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int TimeAtFrame(int frame, Time type = EXACT) const;
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/// @brief Get the components of the SMPTE timecode for the given time
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/// @param[out] h Hours component
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/// @param[out] m Minutes component
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/// @param[out] s Seconds component
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/// @param[out] f Frames component
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///
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/// For NTSC (30000/1001), this generates proper SMPTE timecodes with drop
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/// frames handled. For multiples of NTSC, this multiplies the number of
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/// dropped frames. For other non-integral frame rates, it drops frames in
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/// an undefined manner which results in no more than half a second error
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/// from wall clock time.
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///
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/// For integral frame rates, no frame dropping occurs.
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void SmpteAtTime(int ms, int *h, int *m, int *s, int *f) const;
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/// @brief Get the components of the SMPTE timecode for the given frame
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/// @param[out] h Hours component
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/// @param[out] m Minutes component
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/// @param[out] s Seconds component
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/// @param[out] f Frames component
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///
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/// For NTSC (30000/1001), this generates proper SMPTE timecodes with drop
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/// frames handled. For multiples of NTSC, this multiplies the number of
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/// dropped frames. For other non-integral frame rates, it drops frames in
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/// an undefined manner which results in no more than half a second error
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/// from wall clock time.
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///
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/// For integral frame rates, no frame dropping occurs.
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void SmpteAtFrame(int frame, int *h, int *m, int *s, int *f) const;
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/// @brief Get the frame indicated by the SMPTE timecode components
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/// @param h Hours component
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/// @param m Minutes component
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/// @param s Seconds component
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/// @param f Frames component
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/// @return Frame number
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/// @see SmpteAtFrame
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int FrameAtSmpte(int h, int m, int s, int f) const;
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/// @brief Get the time indicated by the SMPTE timecode components
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/// @param h Hours component
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/// @param m Minutes component
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/// @param s Seconds component
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/// @param f Frames component
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/// @return Time in milliseconds
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/// @see SmpteAtTime
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int TimeAtSmpte(int h, int m, int s, int f) const;
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/// @brief Save the current time codes to a file as v2 timecodes
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/// @param file File name
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/// @param length Minimum number of frames to output
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///
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/// The length parameter is only particularly useful for v1 timecodes (and
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/// CFR, but saving CFR timecodes is a bit silly). Extra timecodes generated
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/// to hit length with v2 timecodes will monotonically increase but may not
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/// be otherwise sensible.
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void Save(fs::path const& file, int length = -1) const;
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/// Is this frame rate possibly variable?
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bool IsVFR() const {return timecodes.size() > 1; }
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/// Does this represent a valid frame rate?
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bool IsLoaded() const { return numerator > 0; }
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/// Get average FPS of this frame rate
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double FPS() const { return double(numerator) / denominator; }
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/// Does this frame rate need drop frames for SMPTE timeish frame numbers?
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bool NeedsDropFrames() const { return drop; }
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};
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} // namespace vfr
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} // namespace agi
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