鋒影
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QNX 中播放音頻，用的是libasound 庫。
官方提供的 wave.c 的代碼，用於播放一個wav格式的音頻文件。
但在QNX 6.6 虛擬機裏一直播放不了，原因是虛擬機沒有/dev/snd/ 而且該目錄下也沒什麼設備。繼續看官方的幫助文檔，是要運行/sbin/io-audio加載聲卡驅動才能播放。
The io-audio command can load the following shared objects:
deva-ctrl-4dwave.so
Sound driver for the Trident 4DWave!.
deva-ctrl-audiopci.so
Sound driver for the AudioPCI chip family.
deva-ctrl-cs4281.so
Sound driver for the CS4281.
deva-ctrl-cs46xx.so
Sound driver for the CS46xx family of chips.
deva-ctrl-cyberpro5.so
Sound driver for the CyberPro5XXX.
deva-ctrl-ess1938.so
Sound driver for the ESS1938.
deva-ctrl-geode.so
Sound driver for the National Semiconductor Geode family of chips.
deva-ctrl-i8x0.so
Sound driver for the Intel 8X0.
deva-ctrl-nmg6.so
Sound driver for the Neomagic 6 family of chips.
deva-ctrl-sb.so
Sound driver for Sound Blaster 16 and compatible soundcards.
deva-ctrl-via686.so
Sound driver for the VIA686.
deva-ctrl-vortex.so
Sound driver for the Vortex.
deva-ctrl-ymfds1.so
Sound driver for the Yamaha DS1.
deva-mixer-ac97.so
Mixer DLL for the AC97 codec.
deva-ak4531.so
Mixer DLL for the AK4531 codec.
deva-util-restore.so
Shared object used to restore an audio driver’s state.
在虛擬機內執行：
/sbin/io-audio -d audiopci
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加載驅動後，出現了/dev/snd/ 目錄，而且目錄下有文件
# /sbin/io-audio -d audiopci
# ls /dev/snd/
controlC0 mixerC0D0 pcmC0D0c pcmC0D0p pcmC0D1p pcmPreferredc pcmPreferredp
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這樣就可以用官網那個例子進行播放了，播放命令如下：
# ./playWave -a 0:0 Wave1.wav
Using card 0 device 0
SampleRate = 11025, Channels = 2, SampleBits = 16
Format Signed 16-bit Little Endian
Frag Size 131072
Total Frags 2
Rate 11025
Voices 2
Mixer Pcm Group [PCM]
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將wave.c 中調音量等複雜功能裁剪掉，寫成一個只播放的demo:
#include <errno.h>
#include <fcntl.h>
#include <gulliver.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/termio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/slogcodes.h>
#include <ctype.h>
#include <limits.h>
#include <sys/asoundlib.h>
#define max(a,b) (a>b)?a:b
#define min(a,b) (a<b)?a:b
const char *kRiffId = "RIFF";
const char *kWaveId = "WAVE";
typedef struct
{
char tag[4];
long length;
}
RiffTag;
typedef struct
{
char Riff[4];
long Size;
char Wave[4];
}
RiffHdr;
typedef struct
{
short FormatTag;
short Channels;
long SamplesPerSec;
long AvgBytesPerSec;
short BlockAlign;
short BitsPerSample;
}
WaveHdr;
int err (char *msg)
{
perror (msg);
return -1;
}
int FindTag (FILE * fp, const char *tag)
{
int retVal;
RiffTag tagBfr = { "", 0 };
retVal = 0;
// Keep reading until we find the tag or hit the EOF.
while (fread ((unsigned char *) &tagBfr, sizeof (tagBfr), 1, fp))
{
// If this is our tag, set the length and break.
if (strncmp (tag, tagBfr.tag, sizeof tagBfr.tag) == 0)
{
retVal = ENDIAN_LE32 (tagBfr.length);
break;
}
// Skip ahead the specified number of bytes in the stream
fseek (fp, tagBfr.length, SEEK_CUR);
}
// Return the result of our operation
return (retVal);
}
int CheckHdr (FILE * fp)
{
RiffHdr riffHdr = { "", 0 };
// Read the header and, if successful, play the file
// file or WAVE file.
if (fread ((unsigned char *) &riffHdr, sizeof (RiffHdr), 1, fp) == 0)
return 0;
if (strncmp (riffHdr.Riff, kRiffId, strlen (kRiffId)) ||
strncmp (riffHdr.Wave, kWaveId, strlen (kWaveId)))
return -1;
return 0;
}
int dev_raw (int fd)
{
struct termios termios_p;
if (tcgetattr (fd, &termios_p))
return (-1);
termios_p.c_cc[VMIN] = 1;
termios_p.c_cc[VTIME] = 0;
termios_p.c_lflag &= ~(ECHO | ICANON | ISIG | ECHOE | ECHOK | ECHONL);
termios_p.c_oflag &= ~(OPOST);
return (tcsetattr (fd, TCSANOW, &termios_p));
}
int dev_unraw (int fd)
{
struct termios termios_p;
if (tcgetattr (fd, &termios_p))
return (-1);
termios_p.c_lflag |= (ECHO | ICANON | ISIG | ECHOE | ECHOK | ECHONL);
termios_p.c_oflag |= (OPOST);
return (tcsetattr (fd, TCSAFLUSH, &termios_p));
}
//*****************************************************************************
// ./playWave Wave1.wav
//*****************************************************************************
int main (int argc, char **argv)
{
snd_pcm_t *pcm_handle;
FILE *file1;
WaveHdr wavHdr1;
int mSamples;
int mSampleRate;
int mSampleChannels;
int mSampleBits;
char *mSampleBfr1;
int verbose = 0;
int rtn;
snd_pcm_channel_info_t pi;
snd_mixer_t *mixer_handle;
snd_mixer_group_t group;
snd_pcm_channel_params_t pp;
snd_pcm_channel_setup_t setup;
int bsize, n, N = 0;
fd_set rfds, wfds;
int num_frags = -1;
char name[_POSIX_PATH_MAX] ="pcmC0D0p";
int card = -1;
int dev = 0;
//兩種方式打開音頻設備; 首選 打開設備 /dev/snd/pcmC0D0p , 設備名根據實際情況變化;
if (name[0] != '\0')
printf ("Using device /dev/snd/%s\n", name);
else
printf ("Using card %d device %d \n", card, dev);
setvbuf (stdin, NULL, _IONBF, 0);
if (name[0] != '\0')
{
snd_pcm_info_t info;
if ((rtn = snd_pcm_open_name (&pcm_handle, name, SND_PCM_OPEN_PLAYBACK)) < 0)
{
return err ((char *)"open_name");
}
rtn = snd_pcm_info (pcm_handle, &info);
card = info.card;
}
else
{
if (card == -1)
{
if ((rtn = snd_pcm_open_preferred (&pcm_handle, &card, &dev, SND_PCM_OPEN_PLAYBACK)) < 0)
return err ((char *)"device open");
}
else
{
if ((rtn = snd_pcm_open (&pcm_handle, card, dev, SND_PCM_OPEN_PLAYBACK)) < 0)
return err ((char *)"device open");
}
}
if (argc < 2)
return err ((char *)"no file specified");
if ((file1 = fopen (argv[1], "r")) == 0)
return err ((char *)"file open #1");
if (CheckHdr (file1) == -1)
return err ((char *)"CheckHdr #1");
mSamples = FindTag (file1, "fmt ");
fread (&wavHdr1, sizeof (wavHdr1), 1, file1);
fseek (file1, (mSamples - sizeof (WaveHdr)), SEEK_CUR);
mSampleRate = ENDIAN_LE32 (wavHdr1.SamplesPerSec);
mSampleChannels = ENDIAN_LE16 (wavHdr1.Channels);
mSampleBits = ENDIAN_LE16 (wavHdr1.BitsPerSample);
printf ("SampleRate = %d, Channels = %d, SampleBits = %d\n", mSampleRate, mSampleChannels,
mSampleBits);
/* disabling mmap is not actually required in this example but it is included to
* demonstrate how it is used when it is required.
*/
if ((rtn = snd_pcm_plugin_set_disable (pcm_handle, PLUGIN_DISABLE_MMAP)) < 0)
{
fprintf (stderr, "snd_pcm_plugin_set_disable failed: %s\n", snd_strerror (rtn));
return -1;
}
memset (&pi, 0, sizeof (pi));
pi.channel = SND_PCM_CHANNEL_PLAYBACK;
if ((rtn = snd_pcm_plugin_info (pcm_handle, &pi)) < 0)
{
fprintf (stderr, "snd_pcm_plugin_info failed: %s\n", snd_strerror (rtn));
return -1;
}
memset (&pp, 0, sizeof (pp));
pp.mode = SND_PCM_MODE_BLOCK;
pp.channel = SND_PCM_CHANNEL_PLAYBACK;
pp.start_mode = SND_PCM_START_FULL;
pp.stop_mode = SND_PCM_STOP_STOP;
pp.buf.block.frag_size = pi.max_fragment_size;
pp.buf.block.frags_max = num_frags;
pp.buf.block.frags_min = 1;
pp.format.interleave = 1;
pp.format.rate = mSampleRate;
pp.format.voices = mSampleChannels;
if (ENDIAN_LE16 (wavHdr1.FormatTag) == 6)
pp.format.format = SND_PCM_SFMT_A_LAW;
else if (ENDIAN_LE16 (wavHdr1.FormatTag) == 7)
pp.format.format = SND_PCM_SFMT_MU_LAW;
else if (mSampleBits == 8)
pp.format.format = SND_PCM_SFMT_U8;
else if (mSampleBits == 24)
pp.format.format = SND_PCM_SFMT_S24;
else
pp.format.format = SND_PCM_SFMT_S16_LE;
strcpy (pp.sw_mixer_subchn_name, "Wave playback channel");
if ((rtn = snd_pcm_plugin_params (pcm_handle, &pp)) < 0)
{
fprintf (stderr, "snd_pcm_plugin_params failed: %s\n", snd_strerror (rtn));
return -1;
}
if ((rtn = snd_pcm_plugin_prepare (pcm_handle, SND_PCM_CHANNEL_PLAYBACK)) < 0)
fprintf (stderr, "snd_pcm_plugin_prepare failed: %s\n", snd_strerror (rtn));
memset (&setup, 0, sizeof (setup));
memset (&group, 0, sizeof (group));
setup.channel = SND_PCM_CHANNEL_PLAYBACK;
setup.mixer_gid = &group.gid;
if ((rtn = snd_pcm_plugin_setup (pcm_handle, &setup)) < 0)
{
fprintf (stderr, "snd_pcm_plugin_setup failed: %s\n", snd_strerror (rtn));
return -1;
}
printf ("Format %s \n", snd_pcm_get_format_name (setup.format.format));
printf ("Frag Size %d \n", setup.buf.block.frag_size);
printf ("Total Frags %d \n", setup.buf.block.frags);
printf ("Rate %d \n", setup.format.rate);
printf ("Voices %d \n", setup.format.voices);
bsize = setup.buf.block.frag_size;
if (group.gid.name[0] == 0)
{
printf ("Mixer Pcm Group [%s] Not Set \n", group.gid.name);
exit (-1);
}
printf ("Mixer Pcm Group [%s]\n", group.gid.name);
if ((rtn = snd_mixer_open (&mixer_handle, card, setup.mixer_device)) < 0)
{
fprintf (stderr, "snd_mixer_open failed: %s\n", snd_strerror (rtn));
return -1;
}
mSamples = FindTag (file1, "data");
mSampleBfr1 = (char *)malloc (bsize);
FD_ZERO (&rfds);
FD_ZERO (&wfds);
n = 1;
while (N < mSamples && n > 0)
{
if (tcgetpgrp (0) == getpid ())
FD_SET (STDIN_FILENO, &rfds);
FD_SET (snd_mixer_file_descriptor (mixer_handle), &rfds);
FD_SET (snd_pcm_file_descriptor (pcm_handle, SND_PCM_CHANNEL_PLAYBACK), &wfds);
rtn = max (snd_mixer_file_descriptor (mixer_handle),
snd_pcm_file_descriptor (pcm_handle, SND_PCM_CHANNEL_PLAYBACK));
if (select (rtn + 1, &rfds, &wfds, NULL, NULL) == -1)
return err ((char *)"select");
if (FD_ISSET (STDIN_FILENO, &rfds))
{
if ((rtn = snd_mixer_group_read (mixer_handle, &group)) < 0)
fprintf (stderr, "snd_mixer_group_read failed: %s\n", snd_strerror (rtn));
dev_raw (fileno (stdin));
}
if (FD_ISSET (snd_mixer_file_descriptor (mixer_handle), &rfds))
{
snd_mixer_callbacks_t callbacks = { 0, 0, 0, 0 };
snd_mixer_read (mixer_handle, &callbacks);
}
if (FD_ISSET (snd_pcm_file_descriptor (pcm_handle, SND_PCM_CHANNEL_PLAYBACK), &wfds))
{
snd_pcm_channel_status_t status;
int written = 0;
if ((n = fread (mSampleBfr1, 1, min (mSamples - N, bsize), file1)) <= 0)
continue;
written = snd_pcm_plugin_write (pcm_handle, mSampleBfr1, n);
if (verbose)
printf ("bytes written = %d \n", written);
if (written < n)
{
memset (&status, 0, sizeof (status));
status.channel = SND_PCM_CHANNEL_PLAYBACK;
if (snd_pcm_plugin_status (pcm_handle, &status) < 0)
{
fprintf (stderr, "underrun: playback channel status error\n");
exit (1);
}
if (status.status == SND_PCM_STATUS_READY ||
status.status == SND_PCM_STATUS_UNDERRUN)
{
if (snd_pcm_plugin_prepare (pcm_handle, SND_PCM_CHANNEL_PLAYBACK) < 0)
{
fprintf (stderr, "underrun: playback channel prepare error\n");
exit (1);
}
}
if (written < 0)
written = 0;
written += snd_pcm_plugin_write (pcm_handle, mSampleBfr1 + written, n - written);
}
N += written;
}
}
n = snd_pcm_plugin_flush (pcm_handle, SND_PCM_CHANNEL_PLAYBACK);
rtn = snd_mixer_close (mixer_handle);
rtn = snd_pcm_close (pcm_handle);
fclose (file1);
return (0);
}