Topic: Using BASS_SAMPLE_3D on Linux with a 7.1 card - No Side Channel Audio?

[superhac]

Hi!

Let me start with some background on my setup: 

• Linux (ubuntu 24.04)
  
• Using the info structs my sound card is name=ICUSBAUDIO7D: USB Audio, enabled=1, speakers=8
• A mono wav file.  1 channel.

I first started by modifying the speakers.c example like this:

Code: [Select]

#include <string.h>
#include <regex.h>
#include "bass.h"
#include <stdio.h>
#include <unistd.h>

int BASS_DEVICE_ID = 8;
char* MONO_WAV = "new.wav";


void playChannel(unsigned int speaker)
{
        HSTREAM rets = BASS_StreamCreateFile(FALSE, MONO_WAV, 0, 0, speaker | BASS_SAMPLE_FLOAT | BASS_SAMPLE_MONO);
        BASS_ChannelPlay(rets, TRUE);
        while(BASS_ChannelIsActive(rets) == BASS_ACTIVE_PLAYING) {
                sleep(.5);
        }
        BASS_ChannelFree(rets);
}

const char * getChannelName(unsigned int channel)
{
            switch (channel)
                        {
                                case 0: return "BASS_SPEAKER_FRONTLEFT";
                                case 1: return "BASS_SPEAKER_FRONTRIGHT";
                                case 2: return "BASS_SPEAKER_REARLEFT";
                                case 3: return "BASS_SPEAKER_REARRIGHT";
                                case 4: return "BASS_SPEAKER_CENTER";
                                case 5: return "BASS_SPEAKER_LFE";
                                case 6: return "BASS_SPEAKER_SIDELEFT";
                                case 7: return "BASS_SPEAKER_SIDERIGHT";
                        }

}


int main(int argc, char* argv[])
{
        // 5.1 Setup
        unsigned int sixChan[6] = {BASS_SPEAKER_FRONTLEFT, BASS_SPEAKER_FRONTRIGHT, BASS_SPEAKER_REARLEFT, BASS_SPEAKER_REARRIGHT,
                                   BASS_SPEAKER_CENTER, BASS_SPEAKER_LFE};
        // 7.1 Setup
        unsigned int eightChan[8] = {BASS_SPEAKER_FRONTLEFT, BASS_SPEAKER_FRONTRIGHT, BASS_SPEAKER_REARLEFT, BASS_SPEAKER_REARRIGHT, BASS_SPEAKER_CENTER,
                                     BASS_SPEAKER_LFE, BASS_SPEAKER_SIDELEFT, BASS_SPEAKER_SIDERIGHT};

        printf("Loading: %s\n", MONO_WAV);

        // check the correct BASS was loaded
        if (HIWORD(BASS_GetVersion()) != BASSVERSION) {
                printf("An incorrect version of BASS was loaded");
                return 0;
        }

        // initialize default device
        if (!BASS_Init(BASS_DEVICE_ID, 44100, 0, NULL, NULL)) {
                printf("Can't initialize device");
                return 0;
        }

        BASS_INFO info;
        BASS_GetInfo(&info);
        printf("BASS version: %d\n", BASS_GetVersion());
        printf("Speakers Detected: %d\n", info.speakers);

        if (info.speakers == 6) {
                for(int i=0; i < sizeof(sixChan) / sizeof(sixChan[0]);i++)
                {
                         printf(" Playing Channel: %s \n" , getChannelName(i));
                         playChannel(sixChan[i]);
                }
        }
        else if (info.speakers == 8) {
                for(int i=0; i < sizeof(eightChan) / sizeof(eightChan[0]);i++)
                {
                         printf(" Playing Channel: %s \n" , getChannelName(i));
                         playChannel(eightChan[i]);
                }
        }

        BASS_Free();
        return 0;
}
This works great and all speakers will play my mono wav as shown:

Code: [Select]

Loading: new.wav
BASS version: 33820928
Speakers Detected: 8
 Playing Channel: BASS_SPEAKER_FRONTLEFT
 Playing Channel: BASS_SPEAKER_FRONTRIGHT
 Playing Channel: BASS_SPEAKER_REARLEFT
 Playing Channel: BASS_SPEAKER_REARRIGHT
 Playing Channel: BASS_SPEAKER_CENTER
 Playing Channel: BASS_SPEAKER_LFE
 Playing Channel: BASS_SPEAKER_SIDELEFT
 Playing Channel: BASS_SPEAKER_SIDERIGHT
Now my next step was moving over to the 3dtest.c example.  It detects that I have more then 2 speakers and asks "Multiple speakers were detected. Would you like to use them?"  I choose yes.  I then load my WAV file, press play and set some x and y values for movement.  I get audio out of all the speakers except for the SIDE LEFT and SIDE RIGHT speakers.

Does the BASS 3D audio not support the side speakers?   

Thanks!

[Ian @ un4seen]

BASS does indeed currently only use up to 6 speakers for 3D output (5 really as LFE isn't used). If you happen to want to try generating 3D output on more speakers yourself, that is possible with BASS_StreamCreate (the "chans" parameter goes higher than 6).

[superhac]

Hi Ian.  Thanks for the reply.  I went in and adjusted the 3dtest.c example using this call and I get error 21 (BASS_ERROR_NO3D) when setting up the stream via:

Code: [Select]

newchan = BASS_StreamCreate(44100, 8, BASS_SAMPLE_3D , MyStreamProc, 0)
My callback:

Code: [Select]

DWORD CALLBACK MyStreamProc(HSTREAM handle, void *buffer, DWORD length, void *user)
{
    DWORD c = fread(buffer, 1, length, file); // read the file into the buffer
    if (feof(file)) c |= BASS_STREAMPROC_END; // end of the file/stream
    return c;
}
I'm using the same mono WAV file. 

Am I doing it right?

Thanks.

[Ian @ un4seen]

Unfortunately, it won't be quite that simple. What I meant was that, rather than enabling BASS's 3D processing with the BASS_SAMPLE_3D flag, it would be possible to implement custom 3D processing (eg. calculate the level of the sound for each speaker) and output that via a custom stream. It could perhaps be simplified a bit by using the BASSmix add-on's matrix mixing feature. For example, you could create an 8 channel/speaker mixer (with BASS_Mixer_StreamCreate) and plug the sound into that (with BASS_Mixer_StreamAddChannel), and then use a matrix (with BASS_Mixer_ChannelSetMatrix) to set the level of the sound on each of the speakers. Note you would still need to do the level calculations yourself then, but not the sample data processing.

[superhac]

Ok.  After I re-read your message and continued to play around, it clicked that what you were stating was I need to manually do all the positional audio processing vs using the 3Dsound bass provides.   I get it now.

Thanks for you quick help and response on this!