regarding rate plugin

[remu kelly <remukelly@xxxxxxxxx>]

Hi ,

I am trying to create a new "rate_converter". for start i am trying to create a empty converter, but facing below error:
-----------------------------------
Playing WAVE '/home/Test.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
aplay: set_params:1297: Unable to install hw params:
ACCESS:  RW_INTERLEAVED
FORMAT:  S16_LE
SUBFORMAT:  STD
SAMPLE_BITS: 16
FRAME_BITS: 32
CHANNELS: 2
RATE: 48000
PERIOD_TIME: (21333 21334)
PERIOD_SIZE: NONE
PERIOD_BYTES: (4092 4100)
PERIODS: (3 5)
BUFFER_TIME: (85333 85334)
BUFFER_SIZE: 4096
BUFFER_BYTES: 16384
TICK_TIME: ALL
-----------------------------------

The asound conf is something like below(here 'rateconvtest' is the converter created by me):-
-----------------------
pcm.sl1 {
    type hw

    card 0

    device 0

}
pcm_slave.sl2 {
    pcm sl1
    rate 96000
}
pcm.rchg {
    type rate
    slave sl2
    converter "rateconvtest"
}
-----------------------------

command used is "aplay -vD rchg /home/Test.wav".

the code of the rate converter i have created is like this:-
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

#include <stdio.h>
#include <alsa/asoundlib.h>
#include <alsa/pcm_rate.h>

static snd_pcm_uframes_t input_frames(void *obj, snd_pcm_uframes_t frames) {
    printf("\nrate in frame callback %d\n", frames);   
    return frames ;
}

static snd_pcm_uframes_t output_frames(void *obj, snd_pcm_uframes_t frames) {
    printf("\nrate out frame callback %d\n", frames );   
    return (snd_pcm_uframes_t)(frames * 2);
}

static void pcm_src_free(void *obj) {
}

static int pcm_src_init(void *obj, snd_pcm_rate_info_t *info) {
    printf("\n rate init rate in = %d rate out = %d\n", info->in.rate, info->out.rate);
    return 0;
}

static int pcm_src_adjust_pitch(void *obj, snd_pcm_rate_info_t *info) {
    printf("\n rate pitch rate = %d\n", info->in.rate);
    return 0;
}

static void pcm_src_reset(void *obj) {
    printf("\n rate reset \n");
}

static void pcm_src_convert_s16(void *obj, int16_t *dst, unsigned int dst_frames, const int16_t *src, unsigned int src_frames) {
  
    unsigned int count = src_frames;

    printf("\n rate in s16 convert srcfrm = %d dst frm = %d \n", src_frames, dst_frames);
    memcpy(dst, src, count );
    memcpy(dst + count, src, count );
}

static void pcm_src_close(void *obj) {
     printf("\n rate close success\n");
}

#if SND_PCM_RATE_PLUGIN_VERSION >= 0x010002
static int get_supported_rates(void *obj, unsigned int *rate_min, unsigned int *rate_max) {
    *rate_min = *rate_max = 0; /* both unlimited */
     printf("\n rate supoort rate success\n");
    return 0;
}

static void dump(void *obj, snd_output_t *out) {
    snd_output_printf(out, "Converter: lib-ratetest\n");
}
#endif

static snd_pcm_rate_ops_t pcm_src_ops = {
    .close = pcm_src_close,
    .init = pcm_src_init,
    .free = pcm_src_free,
    .reset = pcm_src_reset,
    .adjust_pitch = pcm_src_adjust_pitch,
    .convert_s16 = pcm_src_convert_s16,
    .input_frames = input_frames,
    .output_frames = output_frames,
#if SND_PCM_RATE_PLUGIN_VERSION >= 0x010002
    .version = SND_PCM_RATE_PLUGIN_VERSION,
    .get_supported_rates = get_supported_rates,
    .dump = dump,
#endif
};

static int pcm_src_open(unsigned int version, snd_pcm_rate_ops_t *ops) {
    printf("\n rate  OPEN \n");

#if SND_PCM_RATE_PLUGIN_VERSION < 0x010002
    if (version != SND_PCM_RATE_PLUGIN_VERSION) {
        fprintf(stderr, "Invalid rate plugin version %x\n", version);
        return -EINVAL;
    }
#endif
   
#if SND_PCM_RATE_PLUGIN_VERSION >= 0x010002
    if (version == 0x010001)
        memcpy(ops, &pcm_src_ops, sizeof(snd_pcm_rate_old_ops_t));
    else
#endif
        *ops = pcm_src_ops;
    printf("\n rate OPEN complete\n");
    return 0;
}

int SND_PCM_RATE_PLUGIN_ENTRY(ratehardsp) (unsigned int version, void **objp, snd_pcm_rate_ops_t *ops) {
    printf("\n rate ENTRY \n");
    *objp = NULL;
    return pcm_src_open(version, ops);
}

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

So , including all the printf statements, that i have added in my code, the actual output looks like this:-
--------------------------------------------------------
rate ENTRY

 rate  OPEN

 rate OPEN complete

 rate supoort rate success
Playing WAVE '/home/Test.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
aplay: set_params:1297: Unable to install hw params:
ACCESS:  RW_INTERLEAVED
FORMAT:  S16_LE
SUBFORMAT:  STD
SAMPLE_BITS: 16
FRAME_BITS: 32
CHANNELS: 2
RATE: 48000
PERIOD_TIME: (21333 21334)
PERIOD_SIZE: NONE
PERIOD_BYTES: (4092 4100)
PERIODS: (3 5)
BUFFER_TIME: (85333 85334)
BUFFER_SIZE: 4096
BUFFER_BYTES: 16384
TICK_TIME: ALL

 rate close success
-----------------------------------------------------

From above i see that call went successful till the ".get_supported_rates = get_supported_rates", is the definition of function "get_supported_rates()" is wrong? OR do i need to look at something else. I am using UBUNTU 16.04 for the development purpose.

please help me.

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