path: root/stream/stream_radio.c

/*
 * radio support
 *
 * Abilities:
 * * Listening v4l compatible radio cards using line-in or
 *   similar cable
 * * Grabbing audio data using -ao pcm or -dumpaudio
 *   (must be compiled with --enable-radio-capture).
 *
 * Initially written by Vladimir Voroshilov <voroshil@univer.omsk.su>.
 * Based on tv.c and tvi_v4l2.c code.
 *
 * This file is part of MPlayer.
 *
 * MPlayer is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * MPlayer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with MPlayer; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <unistd.h>

#if HAVE_RADIO_V4L2
#include <linux/videodev2.h>
#endif

#include <libavutil/avstring.h>

#include "stream.h"
#include "options/m_option.h"
#include "common/msg.h"
#include "stream_radio.h"

#include "osdep/io.h"

#if HAVE_RADIO_CAPTURE
#include "audio_in.h"

#if HAVE_SYS_SOUNDCARD_H
#include <sys/soundcard.h>
#else
#if HAVE_SOUNDCARD_H
#include <soundcard.h>
#else
#include <linux/soundcard.h>
#endif
#endif

#endif

#define _(x) (x)

typedef struct radio_channels_s {
    int index;     ///< channel index in channels list
    float freq;    ///< frequency in MHz
    char name[20]; ///< channel name
    struct radio_channels_s * next;
    struct radio_channels_s * prev;
} radio_channels_t;

/// default values for options
radio_param_t stream_radio_defaults={
    "/dev/radio0", //device;
    "default",     //driver
    NULL,          //channels
    100,           //volume
    NULL,          //adevice
    44100,         //arate
    2,             //achannels
    0,             //freq_channel
    NULL,          //capture
};

typedef struct radio_priv_s {
    struct mp_log      *log;
    int                 radio_fd;          ///< radio device descriptor
    int                 frac;              ///< fraction value (see comment to init_frac)
    radio_channels_t*   radio_channel_list;
    radio_channels_t*   radio_channel_current;
    float rangelow;                        ///< lowest tunable frequency in MHz
    float rangehigh;                       ///< highest tunable frequency in MHz
    const struct radio_driver_s*     driver;
    int                 old_snd_volume;
#if HAVE_RADIO_CAPTURE
    volatile int        do_capture;        ///< is capture enabled
    audio_in_t          audio_in;
    unsigned char*      audio_ringbuffer;
    int                 audio_head;        ///< start of meanfull data in ringbuffer
    int                 audio_tail;        ///< end of meanfull data in ringbuffer
    int                 audio_buffer_size; ///< size of ringbuffer
    int                 audio_cnt;         ///< size of meanfull data inringbuffer
    int                 audio_drop;        ///< number of dropped bytes
    int                 audio_initialized;
#endif
    radio_param_t       *radio_param;
} radio_priv_t;

typedef struct radio_driver_s {
    char* name;
    char* info;
    int (*init_frac)(radio_priv_t* priv);
    void (*set_volume)(radio_priv_t* priv,int volume);
    int (*get_volume)(radio_priv_t* priv,int* volume);
    int (*set_frequency)(radio_priv_t* priv,float frequency);
    int (*get_frequency)(radio_priv_t* priv,float* frequency);
} radio_driver_t;

#define OPT_BASE_STRUCT radio_param_t
static const m_option_t stream_opts_fields[] = {
    OPT_FLOAT("title", freq_channel, 0),
    OPT_STRING("capture", capture, 0),
    {0}
};

static void close_s(struct stream *stream);
#if HAVE_RADIO_CAPTURE
static int clear_buffer(radio_priv_t* priv);
#endif


/*****************************************************************
 * \brief parse channels parameter and store result into list
 * \param freq_channel if channels!=NULL this mean channel number, otherwise - frequency
 * \param pfreq selected frequency (from selected channel or from URL)
 * \result STREAM_OK if success, STREAM_ERROR otherwise
 *
 *  channels option must be in the following format
 *  <frequency>-<name>,<frequency>-<name>,...
 *
 *  '_' will be replaced with spaces.
 *
 *  If channels option is not null, number in movie URL will be treated as
 *  channel position in channel list.
 */
static int parse_channels(radio_priv_t* priv,float freq_channel,float* pfreq){
    char** channels;
    int i;
    int channel = 0;
    if (priv->radio_param->channels){
        /*parsing channels string*/
        channels=priv->radio_param->channels;

        MP_INFO(priv, "Radio channel names detected.\n");
        priv->radio_channel_list = malloc(sizeof(radio_channels_t));
        priv->radio_channel_list->index=1;
        priv->radio_channel_list->next=NULL;
        priv->radio_channel_list->prev=NULL;
        priv->radio_channel_current = priv->radio_channel_list;

        while (*channels) {
            char* tmp = *(channels++);
            char* sep = strchr(tmp,'-');
            if (!sep) continue; // Wrong syntax, but mplayer should not crash
            av_strlcpy(priv->radio_channel_current->name, sep + 1,sizeof(priv->radio_channel_current->name)-1);

            sep[0] = '\0';

            priv->radio_channel_current->freq=atof(tmp);

            if ((priv->radio_channel_current->freq>priv->rangehigh)||(priv->radio_channel_current->freq<priv->rangelow))
                MP_ERR(priv, "Wrong frequency for channel %s\n",
                    priv->radio_channel_current->name);

            while ((sep=strchr(priv->radio_channel_current->name, '_'))) sep[0] = ' ';

            priv->radio_channel_current->next = malloc(sizeof(radio_channels_t));
            priv->radio_channel_current->next->index = priv->radio_channel_current->index + 1;
            priv->radio_channel_current->next->prev = priv->radio_channel_current;
            priv->radio_channel_current->next->next = NULL;
            priv->radio_channel_current = priv->radio_channel_current->next;
        }
        if (priv->radio_channel_current->prev)
            priv->radio_channel_current->prev->next = NULL;
        free(priv->radio_channel_current);

        if (freq_channel)
            channel = freq_channel;
        else
            channel = 1;

        priv->radio_channel_current = priv->radio_channel_list;
        for (i = 1; i < channel; i++)
            if (priv->radio_channel_current->next)
                priv->radio_channel_current = priv->radio_channel_current->next;
        if (priv->radio_channel_current->index!=channel){
            if (((float)((int)freq_channel))!=freq_channel)
                MP_ERR(priv, "Wrong channel number: %.2f\n",freq_channel);
            else
                MP_ERR(priv, "Wrong channel number: %d\n",(int)freq_channel);
            return STREAM_ERROR;
        }
        MP_INFO(priv, "Selected channel: %d - %s (freq: %.2f)\n", priv->radio_channel_current->index,
            priv->radio_channel_current->name, priv->radio_channel_current->freq);
        *pfreq=priv->radio_channel_current->freq;
    }else{
        if (freq_channel){
            MP_INFO(priv, "Radio frequency parameter detected.\n");
            priv->radio_channel_list=malloc(sizeof(radio_channels_t));
            priv->radio_channel_list->next=NULL;
            priv->radio_channel_list->prev=NULL;
            priv->radio_channel_list->index=1;
            snprintf(priv->radio_channel_list->name,sizeof(priv->radio_channel_current->name)-1,"Freq: %.2f",freq_channel);

            priv->radio_channel_current=priv->radio_channel_list;
            *pfreq=freq_channel;
        }
    }
    MP_DBG(priv, "Done parsing channels.\n");
    return STREAM_OK;
}

#if HAVE_RADIO_V4L2
/*****************************************************************
 * \brief get fraction value for using in set_frequency and get_frequency
 * \return STREAM_OK if success, STREAM_ERROR otherwise
 *
 * V4L2_TUNER_CAP_LOW:
 * unit=62.5Hz
 * frac= 1MHz/unit=1000000/62.5 =16000
 *
 * otherwise:
 * unit=62500Hz
 * frac= 1MHz/unit=1000000/62500 =16
 */
static int init_frac_v4l2(radio_priv_t* priv){
    struct v4l2_tuner tuner;

    memset(&tuner,0,sizeof(tuner));
    tuner.index=0;
    if (ioctl(priv->radio_fd, VIDIOC_G_TUNER, &tuner)<0){
        MP_WARN(priv, "Warning: ioctl get tuner failed: %s. Setting frac to %d.\n",strerror(errno),priv->frac);
        return  STREAM_ERROR;
    }
    if(tuner.type!=V4L2_TUNER_RADIO){
        MP_ERR(priv, "%s is no radio device!\n",priv->radio_param->device);
        return STREAM_ERROR;
    }
    if(tuner.capability & V4L2_TUNER_CAP_LOW){
        priv->frac=16000;
        MP_DBG(priv, "tuner is low:yes frac=%d\n",priv->frac);
    }
    else{
        priv->frac=16;
        MP_DBG(priv, "tuner is low:no frac=%d\n",priv->frac);
    }

    priv->rangelow=((float)tuner.rangelow)/priv->frac;
    priv->rangehigh=((float)tuner.rangehigh)/priv->frac;
    MP_VERBOSE(priv, "Allowed frequency range is %.2f-%.2f MHz.\n",priv->rangelow,priv->rangehigh);
    return STREAM_OK;
}

/*****************************************************************
 * \brief tune card to given frequency
 * \param frequency frequency in MHz
 * \return STREAM_OK if success, STREAM_ERROR otherwise
 */
static int set_frequency_v4l2(radio_priv_t* priv,float frequency){
    struct v4l2_frequency freq;

    memset(&freq,0,sizeof(freq));
    freq.tuner=0;
    freq.type=V4L2_TUNER_RADIO;
    freq.frequency=frequency*priv->frac;
    if(ioctl(priv->radio_fd,VIDIOC_S_FREQUENCY,&freq)<0){
        MP_ERR(priv, "ioctl set frequency 0x%x (%.2f) failed: %s\n",freq.frequency,
        frequency,strerror(errno));
        return  STREAM_ERROR;
    }
    return STREAM_OK;
}

/*****************************************************************
 * \brief get current tuned frequency from card
 * \param frequency where to store frequency in MHz
 * \return STREAM_OK if success, STREAM_ERROR otherwise
 */
static int get_frequency_v4l2(radio_priv_t* priv,float* frequency){
    struct v4l2_frequency freq;
    memset(&freq,0,sizeof(freq));
    if (ioctl(priv->radio_fd, VIDIOC_G_FREQUENCY, &freq) < 0) {
        MP_ERR(priv, "ioctl get frequency failed: %s\n",strerror(errno));
        return  STREAM_ERROR;
    }
    *frequency=((float)freq.frequency)/priv->frac;
    return STREAM_OK;
}

/*****************************************************************
 * \brief set volume on radio card
 * \param volume volume level (0..100)
 * \return STREAM_OK if success, STREAM_ERROR otherwise
 */
static void set_volume_v4l2(radio_priv_t* priv,int volume){
    struct v4l2_queryctrl qctrl;
    struct v4l2_control control;

    /*arg must be between 0 and 100*/
    if (volume > 100) volume = 100;
    if (volume < 0) volume = 0;

    memset(&control,0,sizeof(control));
    control.id=V4L2_CID_AUDIO_MUTE;
    control.value = (volume==0?1:0);
    if (ioctl(priv->radio_fd, VIDIOC_S_CTRL, &control)<0){
        MP_WARN(priv, "ioctl set mute failed: %s\n",strerror(errno));
    }

    memset(&qctrl,0,sizeof(qctrl));
    qctrl.id = V4L2_CID_AUDIO_VOLUME;
    if (ioctl(priv->radio_fd, VIDIOC_QUERYCTRL, &qctrl) < 0) {
        MP_WARN(priv, "ioctl query control failed: %s\n",strerror(errno));
        return;
    }

    memset(&control,0,sizeof(control));
    control.id=V4L2_CID_AUDIO_VOLUME;
    control.value=qctrl.minimum+volume*(qctrl.maximum-qctrl.minimum)/100;
    if (ioctl(priv->radio_fd, VIDIOC_S_CTRL, &control) < 0) {
        MP_WARN(priv, "ioctl set volume failed: %s\n",strerror(errno));
    }
}

/*****************************************************************
 * \brief get current volume from radio card
 * \param volume where to store volume level (0..100)
 * \return STREAM_OK if success, STREAM_ERROR otherwise
 */
static int get_volume_v4l2(radio_priv_t* priv,int* volume){
    struct v4l2_queryctrl qctrl;
    struct v4l2_control control;

    memset(&qctrl,0,sizeof(qctrl));
    qctrl.id = V4L2_CID_AUDIO_VOLUME;
    if (ioctl(priv->radio_fd, VIDIOC_QUERYCTRL, &qctrl) < 0) {
        MP_ERR(priv, "ioctl query control failed: %s\n",strerror(errno));
        return STREAM_ERROR;
    }

    memset(&control,0,sizeof(control));
    control.id=V4L2_CID_AUDIO_VOLUME;
    if (ioctl(priv->radio_fd, VIDIOC_G_CTRL, &control) < 0) {
        MP_ERR(priv, "ioctl get volume failed: %s\n",strerror(errno));
        return STREAM_ERROR;
    }

    if (qctrl.maximum==qctrl.minimum)
        *volume=qctrl.minimum;
    else
        *volume=100*(control.value-qctrl.minimum)/(qctrl.maximum-qctrl.minimum);

    /*arg must be between 0 and 100*/
    if (*volume > 100) *volume = 100;
    if (*volume < 0) *volume = 0;

    return STREAM_OK;
}

/* v4l2 driver info structure */
static const radio_driver_t radio_driver_v4l2={
    "v4l2",
    _("Using V4Lv2 radio interface.\n"),
    init_frac_v4l2,
    set_volume_v4l2,
    get_volume_v4l2,
    set_frequency_v4l2,
    get_frequency_v4l2
};
#endif /* HAVE_RADIO_V4L2 */

static inline int init_frac(radio_priv_t* priv){
    return priv->driver->init_frac(priv);
}
static inline int set_frequency(radio_priv_t* priv,float frequency){
    if ((frequency<priv->rangelow)||(frequency>priv->rangehigh)){
        MP_ERR(priv, "Wrong frequency: %.2f\n",frequency);
        return STREAM_ERROR;
    }
    if(priv->driver->set_frequency(priv,frequency)!=STREAM_OK)
        return STREAM_ERROR;

#if HAVE_RADIO_CAPTURE
    if(clear_buffer(priv)!=STREAM_OK){
        MP_ERR(priv, "Clearing buffer failed: %s\n",strerror(errno));
        return  STREAM_ERROR;
    }
#endif
   return STREAM_OK;
}
static inline int get_frequency(radio_priv_t* priv,float* frequency){
    return priv->driver->get_frequency(priv,frequency);
}
static inline void set_volume(radio_priv_t* priv,int volume){
    priv->driver->set_volume(priv,volume);
}
static inline int get_volume(radio_priv_t* priv,int* volume){
    return priv->driver->get_volume(priv,volume);
}


#if !HAVE_RADIO_CAPTURE
/*****************************************************************
 * \brief stub, if capture disabled at compile-time
 * \return STREAM_OK
 */
static inline int init_audio(radio_priv_t *priv){ return STREAM_OK;}
#else
/*****************************************************************
 * \brief making buffer empty
 * \return STREAM_OK if success, STREAM_ERROR otherwise
 *
 * when changing channel we must clear buffer to avoid large switching delay
 */
static int clear_buffer(radio_priv_t* priv){
    if (!priv->do_capture) return STREAM_OK;
    priv->audio_tail = 0;
    priv->audio_head = 0;
    priv->audio_cnt=0;
    memset(priv->audio_ringbuffer,0,priv->audio_in.blocksize);
    return STREAM_OK;
}
/*****************************************************************
 * \brief read next part of data into buffer
 * \return -1 if error occured or no data available yet, otherwise - bytes read
 * NOTE: audio device works in non-blocking mode
 */
static int read_chunk(audio_in_t *ai, unsigned char *buffer)
{
    int ret;

    switch (ai->type) {
#if HAVE_ALSA
    case AUDIO_IN_ALSA:
        //device opened in non-blocking mode
        ret = snd_pcm_readi(ai->alsa.handle, buffer, ai->alsa.chunk_size);
        if (ret != ai->alsa.chunk_size) {
            if (ret < 0) {
                if (ret==-EAGAIN) return -1;
                MP_ERR(ai, "\nError reading audio: %s\n", snd_strerror(ret));
                if (ret == -EPIPE) {
                    if (ai_alsa_xrun(ai) == 0) {
                        MP_ERR(ai, "Recovered from cross-run, some frames may be left out!\n");
                    } else {
                        MP_ERR(ai, "Fatal error, cannot recover!\n");
                    }
                }
            } else {
                MP_ERR(ai, "\nNot enough audio samples!\n");
            }
            return -1;
        }
        return ret;
#endif
#if HAVE_OSS_AUDIO
    case AUDIO_IN_OSS:
    {
        int bt=0;
        /*
            we must return exactly blocksize bytes, so if we have got any bytes
            at first call to read, we will loop untils get all blocksize bytes
            otherwise we will return -1
        */
        while(bt<ai->blocksize){
        //device opened in non-blocking mode
            ret = read(ai->oss.audio_fd, buffer+bt, ai->blocksize-bt);
            if (ret==ai->blocksize) return ret;
            if (ret<0){
                if (errno==EAGAIN && bt==0) return -1; //no data avail yet
                if (errno==EAGAIN) { usleep(1000); continue;} //nilling buffer to blocksize size
                MP_ERR(ai, "\nError reading audio: %s\n", strerror(errno));
                return -1;
            }
            bt+=ret;
        }
        return bt;
    }
#endif
    default:
        return -1;
    }
}
/*****************************************************************
 * \brief grab next frame from audio device
 * \parameter buffer - store buffer
 * \parameter len - store buffer size in bytes
 * \return number of bytes written into buffer
 *
 *     grabs len (or less) bytes from ringbuffer into buffer
 *     if ringbuffer is empty waits until len bytes of data will be available
 *
 *     priv->audio_cnt - size (in bytes) of ringbuffer's filled part
 *     priv->audio_drop - size (in bytes) of dropped data (if no space in ringbuffer)
 *     priv->audio_head - index of first byte in filled part
 *     priv->audio_tail - index of last byte in filled part
 *
 *     NOTE: audio_tail always aligned by priv->audio_in.blocksize
 *         audio_head may NOT.
 */
static int grab_audio_frame(radio_priv_t *priv, char *buffer, int len)
{
    int i;
    MP_TRACE(priv, "%s: in buffer=%d dropped=%d\n","grab_audio_frame",priv->audio_cnt,priv->audio_drop);
    /* Cache buffer must be filled by some audio packets when playing starts.
       Otherwise MPlayer will quit with EOF error.
       Probably, there is need more carefull checking rather than simple 'for' loop
       (something like timer or similar).

       1000ms delay will happen only at first buffer filling. At next call function
       just fills buffer until either buffer full or no data from driver available.
    */
    for (i=0;i<1000 && !priv->audio_cnt; i++){
        //read_chunk fills exact priv->blocksize bytes
        if(read_chunk(&priv->audio_in, priv->audio_ringbuffer+priv->audio_tail) < 0){
            //sleppeing only when waiting first block to fill empty buffer
            if (!priv->audio_cnt){
                usleep(1000);
                continue;
            }else
                break;
        }
        priv->audio_cnt+=priv->audio_in.blocksize;
        priv->audio_tail = (priv->audio_tail+priv->audio_in.blocksize) % priv->audio_buffer_size;
    }
    if(priv->audio_cnt<len)
        len=priv->audio_cnt;
    memcpy(buffer, priv->audio_ringbuffer+priv->audio_head,len);
    priv->audio_head = (priv->audio_head+len) % priv->audio_buffer_size;
    priv->audio_cnt-=len;
    return len;
}
/*****************************************************************
 * \brief init audio device
 * \return STREAM_OK if success, STREAM_ERROR otherwise
 */
static int init_audio(radio_priv_t *priv)
{
    int is_oss=1;
    int seconds=2;
    char* tmp;
    if (priv->audio_initialized) return 1;

    /* do_capture==0 mplayer was not started with capture keyword, so disabling capture*/
    if(!priv->do_capture)
        return STREAM_OK;

    if (!priv->radio_param->adevice){
        priv->do_capture=0;
        return STREAM_OK;
    }

    priv->do_capture=1;
    MP_VERBOSE(priv, "Starting capture stuff.\n");
#if HAVE_ALSA
    while ((tmp = strrchr(priv->radio_param->adevice, '='))){
        tmp[0] = ':';
        //adevice option looks like ALSA device name. Switching to ALSA
        is_oss=0;
    }
    while ((tmp = strrchr(priv->radio_param->adevice, '.')))
        tmp[0] = ',';
#endif

    if(audio_in_init(&priv->audio_in, priv->log, is_oss?AUDIO_IN_OSS:AUDIO_IN_ALSA)<0){
        MP_ERR(priv, "audio_in_init failed.\n");
    }

    audio_in_set_device(&priv->audio_in, priv->radio_param->adevice);
    audio_in_set_channels(&priv->audio_in, priv->radio_param->achannels);
    audio_in_set_samplerate(&priv->audio_in, priv->radio_param->arate);

    if (audio_in_setup(&priv->audio_in) < 0) {
        MP_ERR(priv, "audio_in_setup call failed: %s\n", strerror(errno));
        return STREAM_ERROR;
    }
#if HAVE_OSS_AUDIO
    if(is_oss)
        ioctl(priv->audio_in.oss.audio_fd, SNDCTL_DSP_NONBLOCK, 0);
#endif
#if HAVE_ALSA
    if(!is_oss)
        snd_pcm_nonblock(priv->audio_in.alsa.handle,1);
#endif

    priv->audio_buffer_size = seconds*priv->audio_in.samplerate*priv->audio_in.channels*
            priv->audio_in.bytes_per_sample+priv->audio_in.blocksize;
    if (priv->audio_buffer_size < 256*priv->audio_in.blocksize)
        priv->audio_buffer_size = 256*priv->audio_in.blocksize;
    MP_VERBOSE(priv, "Audio capture - buffer=%d bytes (block=%d bytes).\n",
        priv->audio_buffer_size,priv->audio_in.blocksize);
    /* start capture */
    priv->audio_ringbuffer = calloc(1, priv->audio_buffer_size);
    if (!priv->audio_ringbuffer) {
        MP_ERR(priv, "cannot allocate audio buffer (block=%d,buf=%d): %s\n",priv->audio_in.blocksize, priv->audio_buffer_size, strerror(errno));
        return STREAM_ERROR;
    }
    priv->audio_head = 0;
    priv->audio_tail = 0;
    priv->audio_cnt = 0;
    priv->audio_drop = 0;

    audio_in_start_capture(&priv->audio_in);

    priv->audio_initialized = 1;

    return STREAM_OK;
}
#endif /* HAVE_RADIO_CAPTURE */

/*-------------------------------------------------------------------------
 for call from mplayer.c
--------------------------------------------------------------------------*/
/*****************************************************************
 * \brief public wrapper for get_frequency
 * \parameter frequency pointer to float, which will contain frequency in MHz
 * \return 1 if success,0 - otherwise
 */
int radio_get_freq(struct stream *stream, float *frequency){
    radio_priv_t* priv=(radio_priv_t*)stream->priv;

    if (!frequency)
	return 0;
    if (get_frequency(priv,frequency)!=STREAM_OK){
        return 0;
    }
    return 1;
}
/*****************************************************************
 * \brief public wrapper for set_frequency
 * \parameter frequency frequency in MHz
 * \return 1 if success,0 - otherwise
 */
int radio_set_freq(struct stream *stream, float frequency){
    radio_priv_t* priv=(radio_priv_t*)stream->priv;

    if (set_frequency(priv,frequency)!=STREAM_OK){
        return 0;
    }
    if (get_frequency(priv,&frequency)!=STREAM_OK){
        return 0;
    }
    MP_INFO(priv, "Current frequency: %.2f\n",frequency);
    return 1;
}

/*****************************************************************
 * \brief tune current frequency by step_interval value
 * \parameter step_interval increment value
 * \return 1 if success,0 - otherwise
 *
 */
int radio_step_freq(struct stream *stream, float step_interval){
    float frequency;
    radio_priv_t* priv=(radio_priv_t*)stream->priv;

    if (get_frequency(priv,&frequency)!=STREAM_OK)
        return 0;

    frequency+=step_interval;
    if (frequency>priv->rangehigh)
        frequency=priv->rangehigh;
    if (frequency<priv->rangelow)
        frequency=priv->rangelow;

    return radio_set_freq(stream,frequency);
}
/*****************************************************************
 * \brief step channel up or down
 * \parameter direction RADIO_CHANNEL_LOWER - go to prev channel,RADIO_CHANNEL_HIGHER - to next
 * \return 1 if success,0 - otherwise
 *
 *  if channel parameter is NULL function prints error message and does nothing, otherwise
 *  changes channel to prev or next in list
 */
int radio_step_channel(struct stream *stream, int direction) {
    radio_priv_t* priv=(radio_priv_t*)stream->priv;

    if (priv->radio_channel_list) {
        switch (direction){
            case  RADIO_CHANNEL_HIGHER:
                if (priv->radio_channel_current->next)
                    priv->radio_channel_current = priv->radio_channel_current->next;
                else
                    priv->radio_channel_current = priv->radio_channel_list;
                if(!radio_set_freq(stream,priv->radio_channel_current->freq))
                    return 0;
                MP_VERBOSE(priv, "Selected channel: %d - %s (freq: %.2f)\n",
                    priv->radio_channel_current->index, priv->radio_channel_current->name,
                    priv->radio_channel_current->freq);
            break;
            case RADIO_CHANNEL_LOWER:
                if (priv->radio_channel_current->prev)
                    priv->radio_channel_current = priv->radio_channel_current->prev;
                else
                    while (priv->radio_channel_current->next)
                        priv->radio_channel_current = priv->radio_channel_current->next;
                if(!radio_set_freq(stream,priv->radio_channel_current->freq))
                    return 0;
                MP_VERBOSE(priv, "Selected channel: %d - %s (freq: %.2f)\n",
                priv->radio_channel_current->index, priv->radio_channel_current->name,
                priv->radio_channel_current->freq);
            break;
        }
    }else
        MP_ERR(priv, "Can not change channel: no channel list given.\n");
    return 1;
}

/*****************************************************************
 * \brief change channel to one with given index
 * \parameter channel string, containing channel number
 * \return 1 if success,0 - otherwise
 *
 *  if channel parameter is NULL function prints error message and does nothing, otherwise
 *  changes channel to given
 */
int radio_set_channel(struct stream *stream, char *channel) {
    radio_priv_t* priv=(radio_priv_t*)stream->priv;
    int i, channel_int;
    radio_channels_t* tmp;
    char* endptr;

    if (*channel=='\0')
        MP_ERR(priv, "Wrong channel name: %s\n",channel);

    if