ref: 797a9a563b2e90849bc6eb79169a9381896eeb15
parent: 90f7206384d54cee5cee40f3e7c64b7a7c43cb26
author: Simon Howard <fraggle@gmail.com>
date: Sat Apr 26 20:58:59 EDT 2014
music: Add loop point Ogg/Flac metadata support. ZDoom has defined a format for Vorbis metadata comments named LOOP_START and LOOP_END that allow the start and end points to be defined in .ogg and .flac files for looping music. Add support for these (they are used in Brandon Blume's SC-55 recordings).
--- a/src/doom/s_sound.c
+++ b/src/doom/s_sound.c
@@ -518,6 +518,8 @@
sfxinfo_t* sfx;
channel_t* c;
+ I_UpdateSound();
+
for (cnum=0; cnum<snd_channels; cnum++)
{c = &channels[cnum];
--- a/src/heretic/s_sound.c
+++ b/src/heretic/s_sound.c
@@ -452,6 +452,8 @@
int absx;
int absy;
+ I_UpdateSound();
+
listener = GetSoundListener();
if (snd_MaxVolume == 0)
{--- a/src/hexen/s_sound.c
+++ b/src/hexen/s_sound.c
@@ -706,6 +706,8 @@
int absx;
int absy;
+ I_UpdateSound();
+
// If we are looping a CD track, we need to check if it has
// finished playing and needs to restart.
if (cdmusic && ShouldRestartCDTrack())
--- a/src/i_sdlmusic.c
+++ b/src/i_sdlmusic.c
@@ -40,6 +40,7 @@
#include "gusconf.h"
#include "i_sound.h"
#include "i_system.h"
+#include "i_swap.h"
#include "m_argv.h"
#include "m_config.h"
#include "m_misc.h"
@@ -51,6 +52,24 @@
#define MID_HEADER_MAGIC "MThd"
#define MUS_HEADER_MAGIC "MUS\x1a"
+#define FLAC_HEADER "fLaC"
+#define OGG_HEADER "OggS"
+
+// Looping Vorbis metadata tag names. These have been defined by ZDoom
+// for specifying the start and end positions for looping music tracks
+// in .ogg and .flac files.
+// More information is here: http://zdoom.org/wiki/Audio_loop
+#define LOOP_START_TAG "LOOP_START"
+#define LOOP_END_TAG "LOOP_END"
+
+// FLAC metadata headers that we care about.
+#define FLAC_STREAMINFO 0
+#define FLAC_VORBIS_COMMENT 4
+
+// Ogg metadata headers that we care about.
+#define OGG_ID_HEADER 1
+#define OGG_COMMENT_HEADER 3
+
// Structure for music substitution.
// We store a mapping based on SHA1 checksum -> filename of substitute music
// file to play, so that substitution occurs based on content rather than
@@ -67,6 +86,14 @@
char *filename;
} subst_music_t;
+// Structure containing parsed metadata read from a digital music track:
+typedef struct
+{+ boolean valid;
+ unsigned int samplerate_hz;
+ int start_time, end_time;
+} file_metadata_t;
+
static subst_music_t *subst_music = NULL;
static unsigned int subst_music_len = 0;
@@ -94,6 +121,298 @@
static char *temp_timidity_cfg = NULL;
+// If true, we are playing a substitute digital track rather than in-WAD
+// MIDI/MUS track, and file_metadata contains loop metadata.
+static boolean playing_substitute = false;
+static file_metadata_t file_metadata;
+
+// Position (in samples) that we have reached in the current track.
+// This is updated by the TrackPositionCallback function.
+static unsigned int current_track_pos;
+
+// Currently playing music track.
+static Mix_Music *current_track_music = NULL;
+
+// If true, the currently playing track is being played on loop.
+static boolean current_track_loop;
+
+// Given a time string (for LOOP_START/LOOP_END), parse it and return
+// the time (in # samples since start of track) it represents.
+static unsigned int ParseVorbisTime(unsigned int samplerate_hz, char *value)
+{+ char *num_start, *p;
+ unsigned int result = 0;
+ char c;
+
+ if (strchr(value, ':') == NULL)
+ {+ return atoi(value);
+ }
+
+ result = 0;
+ num_start = value;
+
+ for (p = value; *p != '\0'; ++p)
+ {+ if (*p == '.' || *p == ':')
+ {+ c = *p; *p = '\0';
+ result = result * 60 + atoi(num_start);
+ num_start = p + 1;
+ *p = c;
+ }
+
+ if (*p == '.')
+ {+ return result * samplerate_hz
+ + (unsigned int) (atof(p) * samplerate_hz);
+ }
+ }
+
+ return (result * 60 + atoi(num_start)) * samplerate_hz;
+}
+
+// Given a vorbis comment string (eg. "LOOP_START=12345"), set fields
+// in the metadata structure as appropriate.
+static void ParseVorbisComment(file_metadata_t *metadata, char *comment)
+{+ char *eq, *key, *value;
+
+ eq = strchr(comment, '=');
+
+ if (eq == NULL)
+ {+ return;
+ }
+
+ key = comment;
+ *eq = '\0';
+ value = eq + 1;
+
+ if (!strcmp(key, LOOP_START_TAG))
+ {+ metadata->start_time = ParseVorbisTime(metadata->samplerate_hz, value);
+ }
+ else if (!strcmp(key, LOOP_END_TAG))
+ {+ metadata->end_time = ParseVorbisTime(metadata->samplerate_hz, value);
+ }
+}
+
+// Parse a vorbis comments structure, reading from the given file.
+static void ParseVorbisComments(file_metadata_t *metadata, FILE *fs)
+{+ uint32_t buf;
+ unsigned int num_comments, i, comment_len;
+ char *comment;
+
+ // We must have read the sample rate already from an earlier header.
+ if (metadata->samplerate_hz == 0)
+ {+ return;
+ }
+
+ // Skip the starting part we don't care about.
+ if (fread(&buf, 4, 1, fs) < 1)
+ {+ return;
+ }
+ if (fseek(fs, LONG(buf), SEEK_CUR) != 0)
+ {+ return;
+ }
+
+ // Read count field for number of comments.
+ if (fread(&buf, 4, 1, fs) < 1)
+ {+ return;
+ }
+ num_comments = LONG(buf);
+
+ // Read each individual comment.
+ for (i = 0; i < num_comments; ++i)
+ {+ // Read length of comment.
+ if (fread(&buf, 4, 1, fs) < 1)
+ {+ return;
+ }
+
+ comment_len = LONG(buf);
+
+ // Read actual comment data into string buffer.
+ comment = calloc(1, comment_len + 1);
+ if (comment == NULL
+ || fread(comment, 1, comment_len, fs) < comment_len)
+ {+ free(comment);
+ break;
+ }
+
+ // Parse comment string.
+ ParseVorbisComment(metadata, comment);
+ free(comment);
+ }
+}
+
+static void ParseFlacStreaminfo(file_metadata_t *metadata, FILE *fs)
+{+ byte buf[34];
+
+ // Read block data.
+ if (fread(buf, sizeof(buf), 1, fs) < 1)
+ {+ return;
+ }
+
+ // We only care about sample rate and song length.
+ metadata->samplerate_hz = (buf[10] << 12) | (buf[11] << 4)
+ | (buf[12] >> 4);
+ // Song length is actually a 36 bit field, but 32 bits should be
+ // enough for everybody.
+ //metadata->song_length = (buf[14] << 24) | (buf[15] << 16)
+ // | (buf[16] << 8) | buf[17];
+}
+
+static void ParseFlacFile(file_metadata_t *metadata, FILE *fs)
+{+ byte header[4];
+ unsigned int block_type;
+ size_t block_len;
+ boolean last_block;
+
+ for (;;)
+ {+ // Read METADATA_BLOCK_HEADER:
+ if (fread(header, 4, 1, fs) < 1)
+ {+ return;
+ }
+
+ block_type = header[0] & ~0x80;
+ last_block = (header[0] & 0x80) != 0;
+ block_len = (header[1] << 16) | (header[2] << 8) | header[3];
+
+ long pos = ftell(fs);
+ if (pos < 0)
+ {+ return;
+ }
+
+ if (block_type == FLAC_STREAMINFO)
+ {+ ParseFlacStreaminfo(metadata, fs);
+ }
+ else if (block_type == FLAC_VORBIS_COMMENT)
+ {+ ParseVorbisComments(metadata, fs);
+ }
+
+ if (last_block)
+ {+ break;
+ }
+
+ // Seek to start of next block.
+ if (fseek(fs, pos + block_len, SEEK_SET) != 0)
+ {+ return;
+ }
+ }
+}
+
+static void ParseOggIdHeader(file_metadata_t *metadata, FILE *fs)
+{+ byte buf[21];
+
+ if (fread(buf, sizeof(buf), 1, fs) < 1)
+ {+ return;
+ }
+
+ metadata->samplerate_hz = (buf[8] << 24) | (buf[7] << 16)
+ | (buf[6] << 8) | buf[5];
+}
+
+static void ParseOggFile(file_metadata_t *metadata, FILE *fs)
+{+ byte buf[7];
+ unsigned int offset;
+
+ // Scan through the start of the file looking for headers. They
+ // begin '[byte]vorbis' where the byte value indicates header type.
+ memset(buf, 0, sizeof(buf));
+
+ for (offset = 0; offset < 100 * 1024; ++offset)
+ {+ // buf[] is used as a sliding window. Each iteration, we
+ // move the buffer one byte to the left and read an extra
+ // byte onto the end.
+ memmove(buf, buf + 1, sizeof(buf) - 1);
+
+ if (fread(&buf[6], 1, 1, fs) < 1)
+ {+ return;
+ }
+
+ if (!memcmp(buf + 1, "vorbis", 6))
+ {+ switch (buf[0])
+ {+ case OGG_ID_HEADER:
+ ParseOggIdHeader(metadata, fs);
+ break;
+ case OGG_COMMENT_HEADER:
+ ParseVorbisComments(metadata, fs);
+ break;
+ default:
+ break;
+ }
+ }
+ }
+}
+
+static void ReadLoopPoints(char *filename, file_metadata_t *metadata)
+{+ FILE *fs;
+ char header[4];
+
+ metadata->valid = false;
+ metadata->samplerate_hz = 0;
+ metadata->start_time = 0;
+ metadata->end_time = -1;
+
+ fs = fopen(filename, "r");
+
+ if (fs == NULL)
+ {+ return;
+ }
+
+ // Check for a recognized file format; use the first four bytes
+ // of the file.
+
+ if (fread(header, 4, 1, fs) < 1)
+ {+ fclose(fs);
+ return;
+ }
+
+ if (memcmp(header, FLAC_HEADER, 4) == 0)
+ {+ ParseFlacFile(metadata, fs);
+ }
+ else if (memcmp(header, OGG_HEADER, 4) == 0)
+ {+ ParseOggFile(metadata, fs);
+ }
+
+ fclose(fs);
+
+ // Only valid if at the very least we read the sample rate.
+ metadata->valid = metadata->samplerate_hz > 0;
+}
+
// Given a MUS lump, look up a substitute MUS file to play instead
// (or NULL to just use normal MIDI playback).
@@ -532,8 +851,14 @@
return Mix_QuerySpec(&freq, &format, &channels) != 0;
}
-// Initialize music subsystem
+// Callback function that is invoked to track current track position.
+void TrackPositionCallback(int chan, void *stream, int len, void *udata)
+{+ // Position is doubled up twice: for 16-bit samples and for stereo.
+ current_track_pos += len / 4;
+}
+// Initialize music subsystem
static boolean I_SDL_InitMusic(void)
{int i;
@@ -614,6 +939,9 @@
Mix_SetMusicCMD(snd_musiccmd);
}
+ // Register an effect function to track the music position.
+ Mix_RegisterEffect(MIX_CHANNEL_POST, TrackPositionCallback, NULL, NULL);
+
// If we're in GENMIDI mode, try to load sound packs.
if (snd_musicdevice == SNDDEVICE_GENMIDI)
{@@ -658,7 +986,6 @@
static void I_SDL_PlaySong(void *handle, boolean looping)
{- Mix_Music *music = (Mix_Music *) handle;
int loops;
if (!music_initialized)
@@ -671,6 +998,9 @@
return;
}
+ current_track_music = (Mix_Music *) handle;
+ current_track_loop = looping;
+
if (looping)
{loops = -1;
@@ -680,7 +1010,17 @@
loops = 1;
}
- Mix_PlayMusic(music, loops);
+ // Don't loop when playing substitute music, as we do it
+ // ourselves instead.
+ if (playing_substitute && file_metadata.valid)
+ {+ loops = 1;
+ SDL_LockAudio();
+ current_track_pos = 0; // start of track
+ SDL_UnlockAudio();
+ }
+
+ Mix_PlayMusic(current_track_music, loops);
}
static void I_SDL_PauseSong(void)
@@ -715,6 +1055,8 @@
}
Mix_HaltMusic();
+ playing_substitute = false;
+ current_track_music = NULL;
}
static void I_SDL_UnRegisterSong(void *handle)
@@ -777,6 +1119,8 @@
return NULL;
}
+ playing_substitute = false;
+
// See if we're substituting this MUS for a high-quality replacement.
filename = GetSubstituteMusicFile(data, len);
@@ -793,6 +1137,10 @@
}
else
{+ // Read loop point metadata from the file so that we know where
+ // to loop the music.
+ playing_substitute = true;
+ ReadLoopPoints(filename, &file_metadata);
return music;
}
}
@@ -852,6 +1200,72 @@
return Mix_PlayingMusic();
}
+// Get position in substitute music track, in seconds since start of track.
+static double GetMusicPosition(void)
+{+ unsigned int music_pos;
+ int freq;
+
+ Mix_QuerySpec(&freq, NULL, NULL);
+
+ SDL_LockAudio();
+ music_pos = current_track_pos;
+ SDL_UnlockAudio();
+
+ return (double) music_pos / freq;
+}
+
+static void RestartCurrentTrack(void)
+{+ double start = (double) file_metadata.start_time
+ / file_metadata.samplerate_hz;
+
+ // If the track is playing on loop then reset to the start point.
+ // Otherwise we need to stop the track.
+ if (current_track_loop)
+ {+ // If the track finished we need to restart it.
+ if (current_track_music != NULL)
+ {+ Mix_PlayMusic(current_track_music, 1);
+ }
+
+ Mix_SetMusicPosition(start);
+ SDL_LockAudio();
+ current_track_pos = file_metadata.start_time;
+ SDL_UnlockAudio();
+ }
+ else
+ {+ Mix_HaltMusic();
+ current_track_music = NULL;
+ playing_substitute = false;
+ }
+}
+
+// Poll music position; if we have passed the loop point end position
+// then we need to go back.
+static void I_SDL_PollMusic(void)
+{+ if (playing_substitute && file_metadata.valid)
+ {+ double end = (double) file_metadata.end_time
+ / file_metadata.samplerate_hz;
+
+ // If we have reached the loop end point then we have to take action.
+ if (file_metadata.end_time >= 0 && GetMusicPosition() >= end)
+ {+ RestartCurrentTrack();
+ }
+
+ // Have we reached the actual end of track (not loop end)?
+ if (!Mix_PlayingMusic() && current_track_loop)
+ {+ RestartCurrentTrack();
+ }
+ }
+}
+
static snddevice_t music_sdl_devices[] =
{SNDDEVICE_PAS,
@@ -876,6 +1290,6 @@
I_SDL_PlaySong,
I_SDL_StopSong,
I_SDL_MusicIsPlaying,
+ I_SDL_PollMusic,
};
-
--- a/src/i_sound.c
+++ b/src/i_sound.c
@@ -278,6 +278,11 @@
{sound_module->Update();
}
+
+ if (music_module != NULL)
+ {+ music_module->Poll();
+ }
}
static void CheckVolumeSeparation(int *vol, int *sep)
--- a/src/i_sound.h
+++ b/src/i_sound.h
@@ -216,6 +216,10 @@
// Query if music is playing.
boolean (*MusicIsPlaying)(void);
+
+ // Invoked periodically to poll.
+
+ void (*Poll)(void);
} music_module_t;
void I_InitMusic(void);
--- a/src/i_swap.h
+++ b/src/i_swap.h
@@ -39,7 +39,7 @@
// of the macros in the original source and some code relies on it.
#define SHORT(x) ((signed short) SDL_SwapLE16(x))
-#define LONG(x) ((signed long) SDL_SwapLE32(x))
+#define LONG(x) ((signed int) SDL_SwapLE32(x))
// Defines for checking the endianness of the system.