Mercurial > SDL_sound_CoreAudio
view README @ 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 | 41412aa092d1 |
| children | 50bb9a6cebfe |
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SDL_sound. An abstract soundfile decoder. SDL_sound is a library that handles the decoding of several popular sound file formats, such as .WAV and .MP3. It is meant to make the programmer's sound playback tasks simpler. The programmer gives SDL_sound a filename, or feeds it data directly from one of many sources, and then reads the decoded waveform data back at her leisure. If resource constraints are a concern, SDL_sound can process sound data in programmer-specified blocks. Alternately, SDL_sound can decode a whole sound file and hand back a single pointer to the whole waveform. SDL_sound can also handle sample rate, audio format, and channel conversion on-the-fly and behind-the-scenes, if the programmer desires. Please check the website for the most up-to-date information about SDL_sound: http://icculus.org/SDL_sound/ SDL_sound _REQUIRES_ Simple Directmedia Layer (SDL) to function, and cannot be built without it. You can get SDL from http://www.libsdl.org/. SDL_sound has only been tried with the SDL 1.2 series, but may work on older versions. Reports of success or failure are welcome. Some optional external libraries that SDL_sound can use and where to find them: SMPEG (used to decode MP3s): http://icculus.org/smpeg/ libvorbisfile (used to decode OGGs): http://www.xiph.org/ogg/vorbis/ libFLAC (used to decode FLACs): http://flac.sourceforge.net/ libModPlug (used to decode MODs, etc): http://modplug-xmms.sourceforge.net/ libMikMod (used to decode MODs, etc, too): http://www.mikmod.org/ Experimental QuickTime support for the Mac is included, but has not been integrated with the build system, and probably doesn't work with QuickTime for Windows. These external libraries are OPTIONAL. SDL_sound will build and function without them, but various sound file formats are not supported unless these libraries are available. Unless explicitly disabled during initial build configuration, SDL_sound always supports these file formats internally: - Microsoft .WAV files (uncompressed and MS-ADPCM encoded). - Creative Labs .VOC files - Shorten (.SHN) files - Audio Interchange format (AIFF) files - Sun Audio (.AU) files - MIDI files - MP3 files (internal decoder, different than the one SMPEG uses) - Raw waveform data Building/Installing: Please read the INSTALL document. Reporting bugs/commenting: There is a mailing list available. To subscribe, send a blank email to sdlsound-subscribe@icculus.org. This is the best way to get in touch with SDL_sound developers. --ryan. (icculus@clutteredmind.org)