Mercurial > sdl-ios-xcode
view src/audio/SDL_audiocvt.c @ 773:da0a2ad35bf4
Date: Sun, 4 Jan 2004 23:48:19 +0100
From: Max Horn
Subject: Re: Again Audio CD patch
Am 04.01.2004 um 22:38 schrieb Sam Lantinga:
>
> Okay, I fixed the buffering problems by simply using a 4 second buffer
> instead of a 1 second buffer. However, using your code I can't play an
> entire CD - the playback stops after the first song.
>
Found the problem: FSReadFork returns eofErr when the file is finished.
However, we check its return value for errors, and if anything but
noErr occurs, the reader thread aborts its current iteration. That is
bad, because it aborts before it can ever set the flag which tells that
the file is over (also, any remaining data which FSRead did return is
lost - so you'd not hear about to 4 seconds from the end of the file.
Furthermore, the computed data size was 8 bytes to high (I forgot to
account for the fact that the size of an (A)IFF chunk always contains
the chunk header & size fields, too). This is enough to make it work.
However, the end condition is rather fragile, so I tuned some other
things to be pessimistic (check for <= 0 instead of == 0, when eofErr
is encountered enforce mReadFilePosition == mFileLength). You never
know...
The attached patch fixes the issue for me.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 05 Jan 2004 00:57:51 +0000 |
parents | b8d311d90021 |
children | 41a59de7f2ed |
line wrap: on
line source
/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2004 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 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 Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this library; if not, write to the Free Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Sam Lantinga slouken@libsdl.org */ #ifdef SAVE_RCSID static char rcsid = "@(#) $Id$"; #endif /* Functions for audio drivers to perform runtime conversion of audio format */ #include <stdio.h> #include "SDL_error.h" #include "SDL_audio.h" /* Effectively mix right and left channels into a single channel */ void SDL_ConvertMono(SDL_AudioCVT *cvt, Uint16 format) { int i; Sint32 sample; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting to mono\n"); #endif switch (format&0x8018) { case AUDIO_U8: { Uint8 *src, *dst; src = cvt->buf; dst = cvt->buf; for ( i=cvt->len_cvt/2; i; --i ) { sample = src[0] + src[1]; if ( sample > 255 ) { *dst = 255; } else { *dst = sample; } src += 2; dst += 1; } } break; case AUDIO_S8: { Sint8 *src, *dst; src = (Sint8 *)cvt->buf; dst = (Sint8 *)cvt->buf; for ( i=cvt->len_cvt/2; i; --i ) { sample = src[0] + src[1]; if ( sample > 127 ) { *dst = 127; } else if ( sample < -128 ) { *dst = -128; } else { *dst = sample; } src += 2; dst += 1; } } break; case AUDIO_U16: { Uint8 *src, *dst; src = cvt->buf; dst = cvt->buf; if ( (format & 0x1000) == 0x1000 ) { for ( i=cvt->len_cvt/4; i; --i ) { sample = (Uint16)((src[0]<<8)|src[1])+ (Uint16)((src[2]<<8)|src[3]); if ( sample > 65535 ) { dst[0] = 0xFF; dst[1] = 0xFF; } else { dst[1] = (sample&0xFF); sample >>= 8; dst[0] = (sample&0xFF); } src += 4; dst += 2; } } else { for ( i=cvt->len_cvt/4; i; --i ) { sample = (Uint16)((src[1]<<8)|src[0])+ (Uint16)((src[3]<<8)|src[2]); if ( sample > 65535 ) { dst[0] = 0xFF; dst[1] = 0xFF; } else { dst[0] = (sample&0xFF); sample >>= 8; dst[1] = (sample&0xFF); } src += 4; dst += 2; } } } break; case AUDIO_S16: { Uint8 *src, *dst; src = cvt->buf; dst = cvt->buf; if ( (format & 0x1000) == 0x1000 ) { for ( i=cvt->len_cvt/4; i; --i ) { sample = (Sint16)((src[0]<<8)|src[1])+ (Sint16)((src[2]<<8)|src[3]); if ( sample > 32767 ) { dst[0] = 0x7F; dst[1] = 0xFF; } else if ( sample < -32768 ) { dst[0] = 0x80; dst[1] = 0x00; } else { dst[1] = (sample&0xFF); sample >>= 8; dst[0] = (sample&0xFF); } src += 4; dst += 2; } } else { for ( i=cvt->len_cvt/4; i; --i ) { sample = (Sint16)((src[1]<<8)|src[0])+ (Sint16)((src[3]<<8)|src[2]); if ( sample > 32767 ) { dst[1] = 0x7F; dst[0] = 0xFF; } else if ( sample < -32768 ) { dst[1] = 0x80; dst[0] = 0x00; } else { dst[0] = (sample&0xFF); sample >>= 8; dst[1] = (sample&0xFF); } src += 4; dst += 2; } } } break; } cvt->len_cvt /= 2; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Duplicate a mono channel to both stereo channels */ void SDL_ConvertStereo(SDL_AudioCVT *cvt, Uint16 format) { int i; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting to stereo\n"); #endif if ( (format & 0xFF) == 16 ) { Uint16 *src, *dst; src = (Uint16 *)(cvt->buf+cvt->len_cvt); dst = (Uint16 *)(cvt->buf+cvt->len_cvt*2); for ( i=cvt->len_cvt/2; i; --i ) { dst -= 2; src -= 1; dst[0] = src[0]; dst[1] = src[0]; } } else { Uint8 *src, *dst; src = cvt->buf+cvt->len_cvt; dst = cvt->buf+cvt->len_cvt*2; for ( i=cvt->len_cvt; i; --i ) { dst -= 2; src -= 1; dst[0] = src[0]; dst[1] = src[0]; } } cvt->len_cvt *= 2; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Convert 8-bit to 16-bit - LSB */ void SDL_Convert16LSB(SDL_AudioCVT *cvt, Uint16 format) { int i; Uint8 *src, *dst; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting to 16-bit LSB\n"); #endif src = cvt->buf+cvt->len_cvt; dst = cvt->buf+cvt->len_cvt*2; for ( i=cvt->len_cvt; i; --i ) { src -= 1; dst -= 2; dst[1] = *src; dst[0] = 0; } format = ((format & ~0x0008) | AUDIO_U16LSB); cvt->len_cvt *= 2; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Convert 8-bit to 16-bit - MSB */ void SDL_Convert16MSB(SDL_AudioCVT *cvt, Uint16 format) { int i; Uint8 *src, *dst; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting to 16-bit MSB\n"); #endif src = cvt->buf+cvt->len_cvt; dst = cvt->buf+cvt->len_cvt*2; for ( i=cvt->len_cvt; i; --i ) { src -= 1; dst -= 2; dst[0] = *src; dst[1] = 0; } format = ((format & ~0x0008) | AUDIO_U16MSB); cvt->len_cvt *= 2; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Convert 16-bit to 8-bit */ void SDL_Convert8(SDL_AudioCVT *cvt, Uint16 format) { int i; Uint8 *src, *dst; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting to 8-bit\n"); #endif src = cvt->buf; dst = cvt->buf; if ( (format & 0x1000) != 0x1000 ) { /* Little endian */ ++src; } for ( i=cvt->len_cvt/2; i; --i ) { *dst = *src; src += 2; dst += 1; } format = ((format & ~0x9010) | AUDIO_U8); cvt->len_cvt /= 2; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Toggle signed/unsigned */ void SDL_ConvertSign(SDL_AudioCVT *cvt, Uint16 format) { int i; Uint8 *data; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting audio signedness\n"); #endif data = cvt->buf; if ( (format & 0xFF) == 16 ) { if ( (format & 0x1000) != 0x1000 ) { /* Little endian */ ++data; } for ( i=cvt->len_cvt/2; i; --i ) { *data ^= 0x80; data += 2; } } else { for ( i=cvt->len_cvt; i; --i ) { *data++ ^= 0x80; } } format = (format ^ 0x8000); if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Toggle endianness */ void SDL_ConvertEndian(SDL_AudioCVT *cvt, Uint16 format) { int i; Uint8 *data, tmp; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting audio endianness\n"); #endif data = cvt->buf; for ( i=cvt->len_cvt/2; i; --i ) { tmp = data[0]; data[0] = data[1]; data[1] = tmp; data += 2; } format = (format ^ 0x1000); if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Convert rate up by multiple of 2 */ void SDL_RateMUL2(SDL_AudioCVT *cvt, Uint16 format) { int i; Uint8 *src, *dst; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting audio rate * 2\n"); #endif src = cvt->buf+cvt->len_cvt; dst = cvt->buf+cvt->len_cvt*2; switch (format & 0xFF) { case 8: for ( i=cvt->len_cvt; i; --i ) { src -= 1; dst -= 2; dst[0] = src[0]; dst[1] = src[0]; } break; case 16: for ( i=cvt->len_cvt/2; i; --i ) { src -= 2; dst -= 4; dst[0] = src[0]; dst[1] = src[1]; dst[2] = src[0]; dst[3] = src[1]; } break; } cvt->len_cvt *= 2; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Convert rate down by multiple of 2 */ void SDL_RateDIV2(SDL_AudioCVT *cvt, Uint16 format) { int i; Uint8 *src, *dst; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting audio rate / 2\n"); #endif src = cvt->buf; dst = cvt->buf; switch (format & 0xFF) { case 8: for ( i=cvt->len_cvt/2; i; --i ) { dst[0] = src[0]; src += 2; dst += 1; } break; case 16: for ( i=cvt->len_cvt/4; i; --i ) { dst[0] = src[0]; dst[1] = src[1]; src += 4; dst += 2; } break; } cvt->len_cvt /= 2; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } /* Very slow rate conversion routine */ void SDL_RateSLOW(SDL_AudioCVT *cvt, Uint16 format) { double ipos; int i, clen; #ifdef DEBUG_CONVERT fprintf(stderr, "Converting audio rate * %4.4f\n", 1.0/cvt->rate_incr); #endif clen = (int)((double)cvt->len_cvt / cvt->rate_incr); if ( cvt->rate_incr > 1.0 ) { switch (format & 0xFF) { case 8: { Uint8 *output; output = cvt->buf; ipos = 0.0; for ( i=clen; i; --i ) { *output = cvt->buf[(int)ipos]; ipos += cvt->rate_incr; output += 1; } } break; case 16: { Uint16 *output; clen &= ~1; output = (Uint16 *)cvt->buf; ipos = 0.0; for ( i=clen/2; i; --i ) { *output=((Uint16 *)cvt->buf)[(int)ipos]; ipos += cvt->rate_incr; output += 1; } } break; } } else { switch (format & 0xFF) { case 8: { Uint8 *output; output = cvt->buf+clen; ipos = (double)cvt->len_cvt; for ( i=clen; i; --i ) { ipos -= cvt->rate_incr; output -= 1; *output = cvt->buf[(int)ipos]; } } break; case 16: { Uint16 *output; clen &= ~1; output = (Uint16 *)(cvt->buf+clen); ipos = (double)cvt->len_cvt/2; for ( i=clen/2; i; --i ) { ipos -= cvt->rate_incr; output -= 1; *output=((Uint16 *)cvt->buf)[(int)ipos]; } } break; } } cvt->len_cvt = clen; if ( cvt->filters[++cvt->filter_index] ) { cvt->filters[cvt->filter_index](cvt, format); } } int SDL_ConvertAudio(SDL_AudioCVT *cvt) { /* Make sure there's data to convert */ if ( cvt->buf == NULL ) { SDL_SetError("No buffer allocated for conversion"); return(-1); } /* Return okay if no conversion is necessary */ cvt->len_cvt = cvt->len; if ( cvt->filters[0] == NULL ) { return(0); } /* Set up the conversion and go! */ cvt->filter_index = 0; cvt->filters[0](cvt, cvt->src_format); return(0); } /* Creates a set of audio filters to convert from one format to another. Returns -1 if the format conversion is not supported, or 1 if the audio filter is set up. */ int SDL_BuildAudioCVT(SDL_AudioCVT *cvt, Uint16 src_format, Uint8 src_channels, int src_rate, Uint16 dst_format, Uint8 dst_channels, int dst_rate) { /* Start off with no conversion necessary */ cvt->needed = 0; cvt->filter_index = 0; cvt->filters[0] = NULL; cvt->len_mult = 1; cvt->len_ratio = 1.0; /* First filter: Endian conversion from src to dst */ if ( (src_format & 0x1000) != (dst_format & 0x1000) && ((src_format & 0xff) != 8) ) { cvt->filters[cvt->filter_index++] = SDL_ConvertEndian; } /* Second filter: Sign conversion -- signed/unsigned */ if ( (src_format & 0x8000) != (dst_format & 0x8000) ) { cvt->filters[cvt->filter_index++] = SDL_ConvertSign; } /* Next filter: Convert 16 bit <--> 8 bit PCM */ if ( (src_format & 0xFF) != (dst_format & 0xFF) ) { switch (dst_format&0x10FF) { case AUDIO_U8: cvt->filters[cvt->filter_index++] = SDL_Convert8; cvt->len_ratio /= 2; break; case AUDIO_U16LSB: cvt->filters[cvt->filter_index++] = SDL_Convert16LSB; cvt->len_mult *= 2; cvt->len_ratio *= 2; break; case AUDIO_U16MSB: cvt->filters[cvt->filter_index++] = SDL_Convert16MSB; cvt->len_mult *= 2; cvt->len_ratio *= 2; break; } } /* Last filter: Mono/Stereo conversion */ if ( src_channels != dst_channels ) { while ( (src_channels*2) <= dst_channels ) { cvt->filters[cvt->filter_index++] = SDL_ConvertStereo; cvt->len_mult *= 2; src_channels *= 2; cvt->len_ratio *= 2; } /* This assumes that 4 channel audio is in the format: Left {front/back} + Right {front/back} so converting to L/R stereo works properly. */ while ( ((src_channels%2) == 0) && ((src_channels/2) >= dst_channels) ) { cvt->filters[cvt->filter_index++] = SDL_ConvertMono; src_channels /= 2; cvt->len_ratio /= 2; } if ( src_channels != dst_channels ) { /* Uh oh.. */; } } /* Do rate conversion */ cvt->rate_incr = 0.0; if ( (src_rate/100) != (dst_rate/100) ) { Uint32 hi_rate, lo_rate; int len_mult; double len_ratio; void (*rate_cvt)(SDL_AudioCVT *cvt, Uint16 format); if ( src_rate > dst_rate ) { hi_rate = src_rate; lo_rate = dst_rate; rate_cvt = SDL_RateDIV2; len_mult = 1; len_ratio = 0.5; } else { hi_rate = dst_rate; lo_rate = src_rate; rate_cvt = SDL_RateMUL2; len_mult = 2; len_ratio = 2.0; } /* If hi_rate = lo_rate*2^x then conversion is easy */ while ( ((lo_rate*2)/100) <= (hi_rate/100) ) { cvt->filters[cvt->filter_index++] = rate_cvt; cvt->len_mult *= len_mult; lo_rate *= 2; cvt->len_ratio *= len_ratio; } /* We may need a slow conversion here to finish up */ if ( (lo_rate/100) != (hi_rate/100) ) { #if 1 /* The problem with this is that if the input buffer is say 1K, and the conversion rate is say 1.1, then the output buffer is 1.1K, which may not be an acceptable buffer size for the audio driver (not a power of 2) */ /* For now, punt and hope the rate distortion isn't great. */ #else if ( src_rate < dst_rate ) { cvt->rate_incr = (double)lo_rate/hi_rate; cvt->len_mult *= 2; cvt->len_ratio /= cvt->rate_incr; } else { cvt->rate_incr = (double)hi_rate/lo_rate; cvt->len_ratio *= cvt->rate_incr; } cvt->filters[cvt->filter_index++] = SDL_RateSLOW; #endif } } /* Set up the filter information */ if ( cvt->filter_index != 0 ) { cvt->needed = 1; cvt->src_format = src_format; cvt->dst_format = dst_format; cvt->len = 0; cvt->buf = NULL; cvt->filters[cvt->filter_index] = NULL; } return(cvt->needed); }