Mercurial > SDL_sound_CoreAudio
view decoders/au.c @ 474:c66080364dff
Most decoders now report total sample play time, now. Technically, this
breaks binary compatibility with the 1.0 branch, since it extends the
Sound_Sample struct, but most (all?) programs are just passing pointers
allocated by SDL_sound around, and might be okay.
Source-level compatibility is not broken...yet! :)
--ryan.
-------- Original Message --------
Subject: SDL_sound patch: Finding total length of time of sound file.
Date: Sun, 26 Jan 2003 09:31:17 -0800 (PST)
Hi Ryan,
I am working with Eric Wing and helping him modify
SDL_sound. AS part of our efforts in improving and
enhancing SDL_sound, we like to submit this patch. We
modified the codecs to find the total time of a sound
file. Below is the explanation of the patch. The
patch is appended as an attachment to this email.
* MOTIVATION:
We needed the ability to get the total play time of a
sample (And we noticed that we're not the only ones).
Since SDL_sound blocks direct access to the specific
decoders, there is no way for a user to know this
information short of decoding the whole thing.
Because of this, we believe this will be a useful
addition, even though the accuracy may not be perfect
(subject to each decoder) or the information may not
always be available.
* CONTRIBUTORS:
Wesley Leong (modified the majority of the codecs and
verified the results)
Eric Wing (showed everyone how to do modify codec,
modified mikmod)
Wang Lam (modified a handful of codecs, researched
into specs and int overflow)
Ahilan Anantha (modified a few codecs and helped with
integer math)
* GENERAL ISSUES:
We chose the value to be milliseconds as an Sint32.
Milliseconds because that's what Sound_Seek takes as a
parameter and -1 to allow for instances/codecs where
the value could not be determined. We are
not sure if this is the final convention you want, so
we are willing to work with you on this.
We also expect the total_time field to be set on open
and never again modified by SDL_sound. Users may
access it directly much like the sample buffer and
buffer_size. We thought about recomputing the time
on DecodeAll, but since users may seek or decode small
chunks first, not all the data may be there. So this
is better done by the user. This may be good
information to document.
Currently, all the main codecs are implemented except
for QuickTime.
author | Ryan C. Gordon <icculus@icculus.org> |
---|---|
date | Sat, 08 May 2004 08:19:50 +0000 |
parents | fb519e6028e3 |
children | 3e705c9180e5 |
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/* * SDL_sound -- An abstract sound format decoding API. * Copyright (C) 2001 Ryan C. Gordon. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ /* * Sun/NeXT .au decoder for SDL_sound. * Formats supported: 8 and 16 bit linear PCM, 8 bit µ-law. * Files without valid header are assumed to be 8 bit µ-law, 8kHz, mono. * * Please see the file COPYING in the source's root directory. * * This file written by Mattias Engdegĺrd. (f91-men@nada.kth.se) */ #if HAVE_CONFIG_H # include <config.h> #endif #ifdef SOUND_SUPPORTS_AU #include <stdio.h> #include <stdlib.h> #include <string.h> #include "SDL_sound.h" #define __SDL_SOUND_INTERNAL__ #include "SDL_sound_internal.h" static int AU_init(void); static void AU_quit(void); static int AU_open(Sound_Sample *sample, const char *ext); static void AU_close(Sound_Sample *sample); static Uint32 AU_read(Sound_Sample *sample); static int AU_rewind(Sound_Sample *sample); static int AU_seek(Sound_Sample *sample, Uint32 ms); /* * Sometimes the extension ".snd" is used for these files (mostly on the NeXT), * and the magic number comes from this. However it may clash with other * formats and is somewhat of an anachronism, so only .au is used here. */ static const char *extensions_au[] = { "AU", NULL }; const Sound_DecoderFunctions __Sound_DecoderFunctions_AU = { { extensions_au, "Sun/NeXT audio file format", "Mattias Engdegĺrd <f91-men@nada.kth.se>", "http://www.icculus.org/SDL_sound/" }, AU_init, /* init() method */ AU_quit, /* quit() method */ AU_open, /* open() method */ AU_close, /* close() method */ AU_read, /* read() method */ AU_rewind, /* rewind() method */ AU_seek /* seek() method */ }; /* no init/deinit needed */ static int AU_init(void) { return(1); } /* AU_init */ static void AU_quit(void) { /* no-op. */ } /* AU_quit */ struct au_file_hdr { Uint32 magic; Uint32 hdr_size; Uint32 data_size; Uint32 encoding; Uint32 sample_rate; Uint32 channels; }; #define HDR_SIZE 24 enum { AU_ENC_ULAW_8 = 1, /* 8-bit ISDN µ-law */ AU_ENC_LINEAR_8 = 2, /* 8-bit linear PCM */ AU_ENC_LINEAR_16 = 3, /* 16-bit linear PCM */ /* the rest are unsupported (I have never seen them in the wild) */ AU_ENC_LINEAR_24 = 4, /* 24-bit linear PCM */ AU_ENC_LINEAR_32 = 5, /* 32-bit linear PCM */ AU_ENC_FLOAT = 6, /* 32-bit IEEE floating point */ AU_ENC_DOUBLE = 7, /* 64-bit IEEE floating point */ /* more Sun formats, not supported either */ AU_ENC_ADPCM_G721 = 23, AU_ENC_ADPCM_G722 = 24, AU_ENC_ADPCM_G723_3 = 25, AU_ENC_ADPCM_G723_5 = 26, AU_ENC_ALAW_8 = 27 }; struct audec { Uint32 total; Uint32 remaining; Uint32 start_offset; int encoding; }; /* * Read in the AU header from disk. This makes this process safe * regardless of the processor's byte order or how the au_file_hdr * structure is packed. */ static int read_au_header(SDL_RWops *rw, struct au_file_hdr *hdr) { if (SDL_RWread(rw, &hdr->magic, sizeof (hdr->magic), 1) != 1) return(0); hdr->magic = SDL_SwapBE32(hdr->magic); if (SDL_RWread(rw, &hdr->hdr_size, sizeof (hdr->hdr_size), 1) != 1) return(0); hdr->hdr_size = SDL_SwapBE32(hdr->hdr_size); if (SDL_RWread(rw, &hdr->data_size, sizeof (hdr->data_size), 1) != 1) return(0); hdr->data_size = SDL_SwapBE32(hdr->data_size); if (SDL_RWread(rw, &hdr->encoding, sizeof (hdr->encoding), 1) != 1) return(0); hdr->encoding = SDL_SwapBE32(hdr->encoding); if (SDL_RWread(rw, &hdr->sample_rate, sizeof (hdr->sample_rate), 1) != 1) return(0); hdr->sample_rate = SDL_SwapBE32(hdr->sample_rate); if (SDL_RWread(rw, &hdr->channels, sizeof (hdr->channels), 1) != 1) return(0); hdr->channels = SDL_SwapBE32(hdr->channels); return(1); } /* read_au_header */ #define AU_MAGIC 0x2E736E64 /* ".snd", in ASCII (bigendian number) */ static int AU_open(Sound_Sample *sample, const char *ext) { Sound_SampleInternal *internal = sample->opaque; SDL_RWops *rw = internal->rw; int skip, hsize, i, bytes_per_second; struct au_file_hdr hdr; struct audec *dec; char c; /* read_au_header() will do byte order swapping. */ BAIL_IF_MACRO(!read_au_header(rw, &hdr), "AU: bad header", 0); dec = malloc(sizeof *dec); BAIL_IF_MACRO(dec == NULL, ERR_OUT_OF_MEMORY, 0); internal->decoder_private = dec; if (hdr.magic == AU_MAGIC) { /* valid magic */ dec->encoding = hdr.encoding; switch(dec->encoding) { case AU_ENC_ULAW_8: /* Convert 8-bit µ-law to 16-bit linear on the fly. This is slightly wasteful if the audio driver must convert them back, but µ-law only devices are rare (mostly _old_ Suns) */ sample->actual.format = AUDIO_S16SYS; break; case AU_ENC_LINEAR_8: sample->actual.format = AUDIO_S8; break; case AU_ENC_LINEAR_16: sample->actual.format = AUDIO_S16MSB; break; default: free(dec); BAIL_MACRO("AU: Unsupported .au encoding", 0); } /* switch */ sample->actual.rate = hdr.sample_rate; sample->actual.channels = hdr.channels; dec->remaining = hdr.data_size; hsize = hdr.hdr_size; /* skip remaining part of header (input may be unseekable) */ for (i = HDR_SIZE; i < hsize; i++) { if (SDL_RWread(rw, &c, 1, 1) != 1) { free(dec); BAIL_MACRO(ERR_IO_ERROR, 0); } /* if */ } /* for */ } /* if */ else if (__Sound_strcasecmp(ext, "au") == 0) { /* * A number of files in the wild have the .au extension but no valid * header; these are traditionally assumed to be 8kHz µ-law. Handle * them here only if the extension is recognized. */ SNDDBG(("AU: Invalid header, assuming raw 8kHz µ-law.\n")); /* if seeking fails, we lose 24 samples. big deal */ SDL_RWseek(rw, -HDR_SIZE, SEEK_CUR); dec->encoding = AU_ENC_ULAW_8; dec->remaining = (Uint32)-1; /* no limit */ sample->actual.format = AUDIO_S16SYS; sample->actual.rate = 8000; sample->actual.channels = 1; } /* else if */ else { free(dec); BAIL_MACRO("AU: Not an .AU stream.", 0); } /* else */ bytes_per_second = ( ( dec->encoding == AU_ENC_LINEAR_16 ) ? 2 : 1 ) * sample->actual.rate * sample->actual.channels ; sample->total_time = ((dec->remaining == -1) ? (-1) : ( ( dec->remaining / bytes_per_second ) * 1000 ) + ( ( dec->remaining % bytes_per_second ) * 1000 / bytes_per_second ) ); sample->flags = SOUND_SAMPLEFLAG_CANSEEK; dec->total = dec->remaining; dec->start_offset = SDL_RWtell(rw); SNDDBG(("AU: Accepting data stream.\n")); return(1); } /* AU_open */ static void AU_close(Sound_Sample *sample) { Sound_SampleInternal *internal = sample->opaque; free(internal->decoder_private); } /* AU_close */ /* table to convert from µ-law encoding to signed 16-bit samples, generated by a throwaway perl script */ static Sint16 ulaw_to_linear[256] = { -32124,-31100,-30076,-29052,-28028,-27004,-25980,-24956, -23932,-22908,-21884,-20860,-19836,-18812,-17788,-16764, -15996,-15484,-14972,-14460,-13948,-13436,-12924,-12412, -11900,-11388,-10876,-10364, -9852, -9340, -8828, -8316, -7932, -7676, -7420, -7164, -6908, -6652, -6396, -6140, -5884, -5628, -5372, -5116, -4860, -4604, -4348, -4092, -3900, -3772, -3644, -3516, -3388, -3260, -3132, -3004, -2876, -2748, -2620, -2492, -2364, -2236, -2108, -1980, -1884, -1820, -1756, -1692, -1628, -1564, -1500, -1436, -1372, -1308, -1244, -1180, -1116, -1052, -988, -924, -876, -844, -812, -780, -748, -716, -684, -652, -620, -588, -556, -524, -492, -460, -428, -396, -372, -356, -340, -324, -308, -292, -276, -260, -244, -228, -212, -196, -180, -164, -148, -132, -120, -112, -104, -96, -88, -80, -72, -64, -56, -48, -40, -32, -24, -16, -8, 0, 32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956, 23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764, 15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412, 11900, 11388, 10876, 10364, 9852, 9340, 8828, 8316, 7932, 7676, 7420, 7164, 6908, 6652, 6396, 6140, 5884, 5628, 5372, 5116, 4860, 4604, 4348, 4092, 3900, 3772, 3644, 3516, 3388, 3260, 3132, 3004, 2876, 2748, 2620, 2492, 2364, 2236, 2108, 1980, 1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436, 1372, 1308, 1244, 1180, 1116, 1052, 988, 924, 876, 844, 812, 780, 748, 716, 684, 652, 620, 588, 556, 524, 492, 460, 428, 396, 372, 356, 340, 324, 308, 292, 276, 260, 244, 228, 212, 196, 180, 164, 148, 132, 120, 112, 104, 96, 88, 80, 72, 64, 56, 48, 40, 32, 24, 16, 8, 0 }; static Uint32 AU_read(Sound_Sample *sample) { int ret; Sound_SampleInternal *internal = sample->opaque; struct audec *dec = internal->decoder_private; int maxlen; Uint8 *buf; maxlen = internal->buffer_size; buf = internal->buffer; if (dec->encoding == AU_ENC_ULAW_8) { /* We read µ-law samples into the second half of the buffer, so we can expand them to 16-bit samples afterwards */ maxlen >>= 1; buf += maxlen; } /* if */ if (maxlen > dec->remaining) maxlen = dec->remaining; ret = SDL_RWread(internal->rw, buf, 1, maxlen); if (ret == 0) sample->flags |= SOUND_SAMPLEFLAG_EOF; else if (ret == -1) sample->flags |= SOUND_SAMPLEFLAG_ERROR; else { dec->remaining -= ret; if (ret < maxlen) sample->flags |= SOUND_SAMPLEFLAG_EAGAIN; if (dec->encoding == AU_ENC_ULAW_8) { int i; Sint16 *dst = internal->buffer; for (i = 0; i < ret; i++) dst[i] = ulaw_to_linear[buf[i]]; ret <<= 1; /* return twice as much as read */ } /* if */ } /* else */ return(ret); } /* AU_read */ static int AU_rewind(Sound_Sample *sample) { Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; struct audec *dec = (struct audec *) internal->decoder_private; int rc = SDL_RWseek(internal->rw, dec->start_offset, SEEK_SET); BAIL_IF_MACRO(rc != dec->start_offset, ERR_IO_ERROR, 0); dec->remaining = dec->total; return(1); } /* AU_rewind */ static int AU_seek(Sound_Sample *sample, Uint32 ms) { Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; struct audec *dec = (struct audec *) internal->decoder_private; int offset = __Sound_convertMsToBytePos(&sample->actual, ms); int rc; int pos; if (dec->encoding == AU_ENC_ULAW_8) offset >>= 1; /* halve the byte offset for compression. */ pos = (int) (dec->start_offset + offset); rc = SDL_RWseek(internal->rw, pos, SEEK_SET); BAIL_IF_MACRO(rc != pos, ERR_IO_ERROR, 0); dec->remaining = dec->total - offset; return(1); } /* AU_seek */ #endif /* SOUND_SUPPORTS_AU */