[SDL] smpeg and SDL_Mixer

[Robert Diel]

I tried this method and it definitely works better, but it's a bit slow,
and has a really really weird echo.  It sounds like it's being played by
smpeg and then shadowed by the mixer.  Any ideas?  I directly stole the
code from the README.SDL_Mixer in the SMPEG directory.  I am running
SMPEG 0.4.4, if this helps at all. 

Here's the code:
     
     .... SDL INIT STUFF...
   
     /* Open the audio device */
     if(Mix_OpenAudio(44100, MIX_DEFAULT_FORMAT, 2, 1024)==-1){
              fprintf(stderr,
		        "Warning: Couldn't set 11025 Hz 8-bit audio\n- Reason:
%s\n",	SDL_GetError());
		use_audio=0;
     }
    
    SMPEG *mpeg;
    SMPEG_Info info;
    int volume = 100;

    SDL_Delay(1000);
    /* Create the MPEG stream */
    mpeg = SMPEG_new("letsroll.mpg", &info, use_audio);
    if ( SMPEG_error(mpeg) ) {
	fprintf(stderr, "%s: %s\n", "letsroll.mpg",         
SMPEG_error(mpeg));
	SMPEG_delete(mpeg);
    }
    SMPEG_enablevideo(mpeg, use_video);
    SMPEG_enableaudio(mpeg, 0);
	if ( use_audio ) {
                SDL_AudioSpec audiofmt;
                Uint16 format;
                int freq, channels;

                /* Tell SMPEG what the audio format is */
                Mix_QuerySpec(&freq, &format, &channels);
                audiofmt.format = format;
                audiofmt.freq = freq;
                audiofmt.channels = channels;
                SMPEG_actualSpec(mpeg, &audiofmt);

                /* Hook in the MPEG music mixer */
                Mix_HookMusic(myMusicPlayer , mpeg);
                SMPEG_enableaudio(mpeg, 1);
	}
    SMPEG_setvolume(mpeg, volume);
    SMPEG_play(mpeg);
}

//...Linking Directly to SMPEG_playAudio didn't work so well... 
void myMusicPlayer(void *udata, Uint8 *stream, int len)
{
	SMPEG_playAudio((SMPEG*)udata,stream,len);
}


Any suggestions would be helpful.


Robert

On Mon, 2002-12-16 at 21:30, Loren Osborn wrote:
> This is a common problem.  Basically, the problem is that SMPEG syncs
> the video with the audio, which means that SMPEG needs to know how fast
> the audio is consumed.  Otherwise, SMPEG tries to sync with the audio
> cursor, which it can't see... so you get something in the 1 frame per
> second range...
> 
> The solution is two fold:
> 
> 1) When you load the MPEG movie, you need to make sure the sdl_audio
> flag is ZERO!!!...  When this value is non-zero, SMPEG tries to play the
> audio *DIRECTLY* through SDL... If you're using SDL_mixer, you need to
> play through SDL_mixer instead...
> 
> 2) You need to cross hook the SMPEG output to the SDL_mixer input...
> 
> Check out smpeg/README.SDL_mixer for details..
> 
> -Loren
> 
> On Mon, 2002-12-16 at 17:13, Robert Diel wrote:
> > Hello all,
> >     I have been trying to use smpeg and SDL_Mixer together and have had
> > very little luck.  I was wondering if anyone has any tips.  If I open
> > the mixer any audio output from my smpeg goes very slowly.  If I do not
> > open the mixer and just use smpeg the audio plays fine.  Am I doing
> > something incorrectly.  plaympeg says the audio is "Audio MPEG-1 Layer 2
> > 224kbit/s 44100Hz stereo".  I set my MIX_OpenAudio to:
> > 
> > 
> > if(Mix_OpenAudio(441000, MIX_DEFAULT_FORMAT, 2, 1024)
> > 
> > and it goes really slowly.  Now, does MIX just take up that much extra
> > processing, or doesn't it play well with mixer, or do I have a setting
> > wrong?
> > 
> > My guess, is that both smpeg and Mix are trying to service the same
> > resource, the sound buffer, and at double the processing, we have double
> > the cost.  I am hoping this assumption is wrong and that I just have a
> > Mixer setting wrong, and that I don't have to design my own.
> > 
> > Robert
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > _______________________________________________
> > SDL mailing list
> > SDL at libsdl.org
> > http://www.libsdl.org/mailman/listinfo/sdl
> 
> 
> 
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