path: root/tinyDAV/src/audio/tdav_jitterbuffer.c

/* File from: http://cms.speakup.nl/tech/opensource/jitterbuffer/verslag-20051209.pdf/ */

/*******************************************************
* jitterbuffer:
* an application-independent jitterbuffer, which tries
* to achieve the maximum user perception during a call.
* For more information look at:
* http://www.speakup.nl/opensource/jitterbuffer/
*
* Copyright on this file is held by:
* - Jesse Kaijen <jesse@speakup.nl>
* - SpeakUp <info@speakup.nl>
*
* Contributors:
* Jesse Kaijen <jesse@speakup.nl>
*
* This program is free software, distributed under the terms of:
* - the GNU Lesser (Library) General Public License
* - the Mozilla Public License
*
* if you are interested in an different licence type, please contact us.
*
* How to use the jitterbuffer, please look at the comments
* in the headerfile.
*
* Further details on specific implementations,
* please look at the comments in the code file.
*/
#include "tinydav/audio/tdav_jitterbuffer.h"

#if !(HAVE_SPEEX_DSP && HAVE_SPEEX_JB)

#include "tsk_memory.h"

#include <stdlib.h>
#include <string.h>
#include <limits.h>

#define jb_warn(...) (warnf ? warnf(__VA_ARGS__) : (void)0)
#define jb_err(...) (errf ? errf(__VA_ARGS__) : (void)0)
#define jb_dbg(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)

//public functions
jitterbuffer *jb_new();
void jb_reset(jitterbuffer *jb);
void jb_reset_all(jitterbuffer *jb);
void jb_destroy(jitterbuffer *jb);
void jb_set_settings(jitterbuffer *jb, jb_settings *settings);

void jb_get_info(jitterbuffer *jb, jb_info *stats);
void jb_get_settings(jitterbuffer *jb, jb_settings *settings);
float jb_guess_mos(float p, long d, int codec);
int jb_has_frames(jitterbuffer *jb);

void jb_put(jitterbuffer *jb, void *data, int type, long ms, long ts, long now, int codec);
int jb_get(jitterbuffer *jb, void **data, long now, long interpl);



//private functions
static void set_default_settings(jitterbuffer *jb);
static void reset(jitterbuffer *jb);
static long find_pointer(long *array, long max_index, long value);
static void frame_free(jb_frame *frame);

static void put_control(jitterbuffer *jb, void *data, int type, long ts);
static void put_voice(jitterbuffer *jb, void *data, int type, long ms, long ts, int codec);
static void put_history(jitterbuffer *jb, long ts, long now, long ms, int codec);
static void calculate_info(jitterbuffer *jb, long ts, long now, int codec);

static int get_control(jitterbuffer *jb, void **data);
static int get_voice(jitterbuffer *jb, void **data, long now, long interpl);
static int get_voicecase(jitterbuffer *jb, void **data, long now, long interpl, long diff);

static int get_next_frametype(jitterbuffer *jb, long ts);
static long get_next_framets(jitterbuffer *jb);
static jb_frame *get_frame(jitterbuffer *jb, long ts);
static jb_frame *get_all_frames(jitterbuffer *jb);

//debug...
static jb_output_function_t warnf, errf, dbgf;
void jb_setoutput(jb_output_function_t warn, jb_output_function_t err, jb_output_function_t dbg)
{
    warnf = warn;
    errf = err;
    dbgf = dbg;
}


/***********
 * create a new jitterbuffer
 * return NULL if malloc doesn't work
 * else return jb with default_settings.
 */
jitterbuffer *jb_new()
{
    jitterbuffer *jb;

    jb_dbg("N");
    jb = tsk_calloc(1, sizeof(jitterbuffer));
    if (!jb) {
        jb_err("cannot allocate jitterbuffer\n");
        return NULL;
    }
    set_default_settings(jb);
    reset(jb);
    return jb;
}


/***********
 * empty voice messages
 * reset statistics
 * keep the settings
 */
void jb_reset(jitterbuffer *jb)
{
    jb_frame *frame;

    jb_dbg("R");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_reset()\n");
        return;
    }

    //free voice
    while(jb->voiceframes) {
        frame = get_all_frames(jb);
        frame_free(frame);
    }
    //reset stats
    memset(&(jb->info),0,sizeof(jb_info) );
    // set default settings
    reset(jb);
}


/***********
 * empty nonvoice messages
 * empty voice messages
 * reset statistics
 * reset settings to default
 */
void jb_reset_all(jitterbuffer *jb)
{
    jb_frame *frame;

    jb_dbg("r");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_reset_all()\n");
        return;
    }

    // free nonvoice
    while(jb->controlframes) {
        frame = jb->controlframes;
        jb->controlframes = frame->next;
        frame_free(frame);
    }
    // free voice and reset statistics is done by jb_reset
    jb_reset(jb);
    set_default_settings(jb);
}


/***********
 * destroy the jitterbuffer
 * free all the [non]voice frames with reset_all
 * free the jitterbuffer
 */
void jb_destroy(jitterbuffer *jb)
{
    jb_dbg("D");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_destroy()\n");
        return;
    }

    jb_reset_all(jb);
    free(jb);
}


/***********
 * Set settings for the jitterbuffer.
 * Only if a setting is defined it will be written
 * in the jb->settings.
 * This means that no setting can be set to zero
 */
void jb_set_settings(jitterbuffer *jb, jb_settings *settings)
{
    jb_dbg("S");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_set_settings()\n");
        return;
    }

    if (settings->min_jb) {
        jb->settings.min_jb = settings->min_jb;
    }
    if (settings->max_jb) {
        jb->settings.max_jb = settings->max_jb;
    }
    if (settings->max_successive_interp) {
        jb->settings.max_successive_interp = settings->max_successive_interp;
    }
    if (settings->extra_delay) {
        jb->settings.extra_delay = settings->extra_delay;
    }
    if (settings->wait_grow) {
        jb->settings.wait_grow = settings->wait_grow;
    }
    if (settings->wait_shrink) {
        jb->settings.wait_shrink = settings->wait_shrink;
    }
    if (settings->max_diff) {
        jb->settings.max_diff = settings->max_diff;
    }
}


/***********
 * validates the statistics
 * the losspct due the jitterbuffer will be calculated.
 * delay and delay_target will be calculated
 * *stats = info
 */
void jb_get_info(jitterbuffer *jb, jb_info *stats)
{
    long max_index, pointer;

    jb_dbg("I");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_get_info()\n");
        return;
    }

    jb->info.delay = jb->current - jb->min;
    jb->info.delay_target = jb->target - jb->min;

    //calculate the losspct...
    max_index = (jb->hist_pointer < JB_HISTORY_SIZE) ?
                jb->hist_pointer : JB_HISTORY_SIZE-1;
    if (max_index>1) {
        pointer = find_pointer(&jb->hist_sorted_delay[0], max_index,
                               jb->current);
        jb->info.losspct = ((max_index - pointer)*100/max_index);
        if (jb->info.losspct < 0) {
            jb->info.losspct = 0;
        }
    }
    else {
        jb->info.losspct = 0;
    }

    *stats = jb->info;
}


/***********
 * gives the settings for this jitterbuffer
 * *settings = settings
 */
void jb_get_settings(jitterbuffer *jb, jb_settings *settings)
{
    jb_dbg("S");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_get_settings()\n");
        return;
    }

    *settings = jb->settings;
}


/***********
 * returns an estimate on the MOS with given loss, delay and codec
 * if the formula is not present the default will be used
 * please use the JB_CODEC_OTHER if you want to define your own formula
 *
 */
float jb_guess_mos(float p, long d, int codec)
{
    float result;

    switch (codec) {
    case JB_CODEC_GSM_EFR:
        result = (4.31f - 0.23f*p - 0.0071f*d);
        break;

    case JB_CODEC_G723_1:
        result = (3.99f - 0.16f*p - 0.0071f*d);
        break;

    case JB_CODEC_G729:
    case JB_CODEC_G729A:
        result = (4.13f - 0.14f*p - 0.0071f*d);
        break;

    case JB_CODEC_G711x_PLC:
        result = (4.42f - 0.087f*p - 0.0071f*d);
        break;

    case JB_CODEC_G711x:
        result = (4.42f - 0.63f*p - 0.0071f*d);
        break;

    case JB_CODEC_OTHER:
    default:
        result = (4.42f - 0.63f*p - 0.0071f*d);

    }
    return result;
}


/***********
 * if there are any frames left in JB returns JB_OK, otherwise returns JB_EMPTY
 */
int jb_has_frames(jitterbuffer *jb)
{
    jb_dbg("H");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_has_frames()\n");
        return JB_NOJB;
    }

    if(jb->controlframes || jb->voiceframes) {
        return JB_OK;
    }
    else {
        return JB_EMPTY;
    }
}


/***********
 * Put a packet into the jitterbuffers
 * Only the timestamps of voicepackets are put in the history
 * this because the jitterbuffer only works for voicepackets
 * don't put packets twice in history and queue (e.g. transmitting every frame twice)
 * keep track of statistics
 */
void jb_put(jitterbuffer *jb, void *data, int type, long ms, long ts, long now, int codec)
{
    long pointer, max_index;

    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_put()\n");
        return;
    }

    jb->info.frames_received++;

    if (type == JB_TYPE_CONTROL) {
        //put the packet into the contol-queue of the jitterbuffer
        jb_dbg("pC");
        put_control(jb,data,type,ts);

    }
    else if (type == JB_TYPE_VOICE) {
        // only add voice that aren't already in the buffer
        max_index = (jb->hist_pointer < JB_HISTORY_SIZE) ? jb->hist_pointer : JB_HISTORY_SIZE-1;
        pointer = find_pointer(&jb->hist_sorted_timestamp[0], max_index, ts);
        if (jb->hist_sorted_timestamp[pointer]==ts) { //timestamp already in queue
            jb_dbg("pT");
            free(data);
            jb->info.frames_dropped_twice++;
        }
        else {   //add
            jb_dbg("pV");
            /* add voicepacket to history */
            put_history(jb,ts,now,ms,codec);
            /*calculate jitterbuffer size*/
            calculate_info(jb, ts, now, codec);
            /*put the packet into the queue of the jitterbuffer*/
            put_voice(jb,data,type,ms,ts,codec);
        }

    }
    else if (type == JB_TYPE_SILENCE) {  //silence
        jb_dbg("pS");
        put_voice(jb,data,type,ms,ts,codec);

    }
    else {  //should NEVER happen
        jb_err("jb_put(): type not known\n");
        free(data);
    }
}


/***********
 * control frames have a higher priority then voice frames
 * returns JB_OK if a frame is available and *data points to the packet
 * returns JB_NOFRAME if it's no time to play voice and no control available
 * returns JB_INTERP if interpolating is required
 * returns JB_EMPTY if no voice frame is in the jitterbuffer (only during silence)
 */
int jb_get(jitterbuffer *jb, void **data, long now, long interpl)
{
    int result;

    jb_dbg("A");
    if (jb == NULL) {
        jb_err("no jitterbuffer in jb_get()\n");
        return JB_NOJB;
    }

    result = get_control(jb, data);
    if (result != JB_OK ) { //no control message available maybe there is voice...
        result = get_voice(jb, data, now, interpl);
    }
    return result;
}


/***********
 * set all the settings to default
 */
static void set_default_settings(jitterbuffer *jb)
{
    jb->settings.min_jb = JB_MIN_SIZE;
    jb->settings.max_jb = JB_MAX_SIZE;
    jb->settings.max_successive_interp = JB_MAX_SUCCESSIVE_INTERP;
    jb->settings.extra_delay = JB_ALLOW_EXTRA_DELAY;
    jb->settings.wait_grow = JB_WAIT_GROW;
    jb->settings.wait_shrink = JB_WAIT_SHRINK;
    jb->settings.max_diff = JB_MAX_DIFF;
}


/***********
 * reset the jitterbuffer so we can start in silence and
 * we start with a new history
 */
static void reset(jitterbuffer *jb)
{
    jb->hist_pointer = 0; //start over
    jb->silence_begin_ts = 0; //no begin_ts defined
    jb->info.silence =1; //we always start in silence
}


/***********
 * Search algorithm
 * @REQUIRE max_index is within array
 *
 * Find the position of value in hist_sorted_delay
 * if value doesn't exist return first pointer where array[low]>value
 * int low;   //the lowest index being examined
 * int max_index; //the highest index being examined
 * int mid;  //the middle index between low and max_index.
 * mid ==(low+max_index)/2
 * at the end low is the position of value or where array[low]>value
 */
static long find_pointer(long *array, long max_index, long value)
{
    register long low, mid, high;
    low = 0;
    high = max_index;
    while (low<=high) {
        mid= (low+high)/2;
        if (array[mid] < value) {
            low = mid+1;
        }
        else {
            high = mid-1;
        }
    }
    while(low < max_index && (array[low]==array[(low+1)]) ) {
        low++;
    }
    return low;
}


/***********
 * free the given frame, afterwards the framepointer is undefined
 */
static void frame_free(jb_frame *frame)
{
    if (frame->data) {
        free(frame->data);
    }
    free(frame);
}


/***********
 * put a nonvoice frame into the nonvoice queue
 */
static void put_control(jitterbuffer *jb, void *data, int type, long ts)
{
    jb_frame *frame, *p;

    frame = malloc(sizeof(jb_frame));
    if(!frame) {
        jb_err("cannot allocate frame\n");
        return;
    }
    frame->data = data;
    frame->ts = ts;
    frame->type = type;
    frame->next = NULL;
    data = NULL;//to avoid stealing memory

    p = jb->controlframes;
    if (p) { //there are already control messages
        if (ts < p->ts) {
            jb->controlframes = frame;
            frame->next = p;
        }
        else {
            while (p->next && (ts >=p->next->ts)) {//sort on timestamps! so find place to put...
                p = p->next;
            }
            if (p->next) {
                frame->next = p->next;
            }
            p->next = frame;
        }
    }
    else {
        jb->controlframes = frame;
    }
}


/***********
 * put a voice or silence frame into the jitterbuffer
 */
static void put_voice(jitterbuffer *jb, void *data, int type, long ms, long ts, int codec)
{
    jb_frame *frame, *p;
    frame = malloc(sizeof(jb_frame));
    if(!frame) {
        jb_err("cannot allocate frame\n");
        return;
    }

    frame->data = data;
    frame->ts = ts;
    frame->ms = ms;
    frame->type = type;
    frame->codec = codec;

    data = NULL; //to avoid stealing the memory location
    /*
     * frames are a circular list, jb->voiceframes points to to the lowest ts,
     * jb->voiceframes->prev points to the highest ts
     */
    if(!jb->voiceframes) {  /* queue is empty */
        jb->voiceframes = frame;
        frame->next = frame;
        frame->prev = frame;
    }
    else {
        p = jb->voiceframes;
        if(ts < p->prev->ts) { //frame is out of order
            jb->info.frames_ooo++;
        }
        if (ts < p->ts) { //frame is lowest, let voiceframes point to it!
            jb->voiceframes = frame;
        }
        else {
            while(ts < p->prev->ts ) {
                p = p->prev;
            }
        }
        frame->next = p;
        frame->prev = p->prev;
        frame->next->prev = frame;
        frame->prev->next = frame;
    }
}


/***********
 * puts the timestamps of a received packet in the history of *jb
 * for later calculations of the size of jitterbuffer *jb.
 *
 * summary of function:
 * - calculate delay difference
 * - delete old value from hist & sorted_history_delay & sorted_history_timestamp if needed
 * - add new value to history & sorted_history_delay & sorted_history_timestamp
 * - we keep sorted_history_delay for calculations
 * - we keep sorted_history_timestamp for ensuring each timestamp isn't put twice in the buffer.
 */
static void put_history(jitterbuffer *jb, long ts, long now, long ms, int codec)
{
    jb_hist_element out, in;
    long max_index, pointer, location;

    // max_index is the highest possible index
    max_index = (jb->hist_pointer < JB_HISTORY_SIZE) ? jb->hist_pointer : JB_HISTORY_SIZE-1;
    location = (jb->hist_pointer % JB_HISTORY_SIZE);

    // we want to delete a value from the jitterbuffer
    // only when we are through the history.
    if (jb->hist_pointer > JB_HISTORY_SIZE-1) {
        /* the value we need to delete from sorted histories */
        out = jb->hist[location];
        //delete delay from hist_sorted_delay
        pointer = find_pointer(&jb->hist_sorted_delay[0], max_index, out.delay);
        /* move over pointer is the position of kicked*/
        if (pointer<max_index) { //only move if we have something to move
            memmove(  &(jb->hist_sorted_delay[pointer]),
                      &(jb->hist_sorted_delay[pointer+1]),
                      ((JB_HISTORY_SIZE-(pointer+1)) * sizeof(long)) );
        }

        //delete timestamp from hist_sorted_timestamp
        pointer = find_pointer(&jb->hist_sorted_timestamp[0], max_index, out.ts);
        /* move over pointer is the position of kicked*/
        if (pointer<max_index) { //only move if we have something to move
            memmove(  &(jb->hist_sorted_timestamp[pointer]),
                      &(jb->hist_sorted_timestamp[pointer+1]),
                      ((JB_HISTORY_SIZE-(pointer+1)) * sizeof(long)) );
        }
    }

    in.delay = now - ts;    //delay of current packet
    in.ts = ts;      //timestamp of current packet
    in.ms = ms;      //length of current packet
    in.codec = codec;      //codec of current packet

    /* adding the new delay to the sorted history
     * first special cases:
     * - delay is the first history stamp
     * - delay > highest history stamp
     */
    if (max_index==0 || in.delay >= jb->hist_sorted_delay[max_index-1]) {
        jb->hist_sorted_delay[max_index] = in.delay;
    }
    else {
        pointer = find_pointer(&jb->hist_sorted_delay[0], (max_index-1), in.delay);
        /* move over and add delay */
        memmove(  &(jb->hist_sorted_delay[pointer+1]),
                  &(jb->hist_sorted_delay[pointer]),
                  ((JB_HISTORY_SIZE-(pointer+1)) * sizeof(long)) );
        jb->hist_sorted_delay[pointer] = in.delay;
    }

    /* adding the new timestamp to the sorted history
     * first special cases:
     * - timestamp is the first history stamp
     * - timestamp > highest history stamp
     */
    if (max_index==0 || in.ts >= jb->hist_sorted_timestamp[max_index-1]) {
        jb->hist_sorted_timestamp[max_index] = in.ts;
    }
    else {

        pointer = find_pointer(&jb->hist_sorted_timestamp[0], (max_index-1), in.ts);
        /* move over and add timestamp */
        memmove(  &(jb->hist_sorted_timestamp[pointer+1]),
                  &(jb->hist_sorted_timestamp[pointer]),
                  ((JB_HISTORY_SIZE-(pointer+1)) * sizeof(long)) );
        jb->hist_sorted_timestamp[pointer] = in.ts;
    }

    /* put the jb_hist_element in the history
    * then increase hist_pointer for next time
    */
    jb->hist[location] = in;
    jb->hist_pointer++;
}


/***********
 * this tries to make a jitterbuffer that behaves like
 * the jitterbuffer proposed in this article:
 * Adaptive Playout Buffer Algorithm for Enhancing Perceived Quality of Streaming Applications
 * by: Kouhei Fujimoto & Shingo Ata & Masayuki Murata
 * http://www.nal.ics.es.osaka-u.ac.jp/achievements/web2002/pdf/journal/k-fujimo02TSJ-AdaptivePlayoutBuffer.pdf
 *
 * it calculates jitter and minimum delay
 * get the best delay for the specified codec

 */
static void calculate_info(jitterbuffer *jb, long ts, long now, int codec)
{
    long diff, size, max_index, d, d1, d2, n;
    float p, p1, p2, A, B;
    //size = how many items there in the history
    size = (jb->hist_pointer < JB_HISTORY_SIZE) ? jb->hist_pointer : JB_HISTORY_SIZE;
    max_index = size-1;

    /*
     * the Inter-Quartile Range can be used for estimating jitter
     * http://www.slac.stanford.edu/comp/net/wan-mon/tutorial.html#variable
     * just take the square root of the iqr for jitter
     */
    jb->info.iqr = jb->hist_sorted_delay[max_index*3/4] - jb->hist_sorted_delay[max_index/4];


    /*
     * The RTP way of calculating jitter.
     * This one is used at the moment, although it is not correct.
     * But in this way the other side understands us.
     */
    diff = now - ts - jb->last_delay;
    if (!jb->last_delay) {
        diff = 0; //this to make sure we won't get odd jitter due first ts.
    }
    jb->last_delay = now - ts;
    if (diff <0) {
        diff = -diff;
    }
    jb->info.jitter = jb->info.jitter + (diff - jb->info.jitter)/16;

    /* jb->min is minimum delay in hist_sorted_delay, we don't look at the lowest 2% */
    /* because sometimes there are odd delays in there */
    jb->min = jb->hist_sorted_delay[(max_index*2/100)];

    /*
     * calculating the preferred size of the jitterbuffer:
     * instead of calculating the optimum delay using the Pareto equation
     * I use look at the array of sorted delays and choose my optimum from there
     * always walk trough a percentage of the history this because imagine following tail:
     * [...., 12, 300, 301 ,302]
     * her we want to discard last three but that won't happen if we won't walk the array
     * the number of frames we walk depends on how scattered the sorted delays are.
     * For that we look at the iqr. The dependencies of the iqr are based on
     * tests we've done here in the lab. But are not optimized.
     */
    //init:
    //the higest delay..
    d = d1= d2 = jb->hist_sorted_delay[max_index]- jb->min;
    A=B=LONG_MIN;
    p = p2 =0;
    n=0;
    p1 = 5; //always look at the top 5%
    if (jb->info.iqr >200) { //with more jitter look at more delays
        p1=25;
    }
    else if (jb->info.iqr >100) {
        p1=20;
    }
    else if (jb->info.iqr >50) {
        p1=11;
    }

    //find the optimum delay..
    while(max_index>10 && (B > A ||p2<p1)) { // By MDI: from ">=" to ">"
        //the packetloss with this delay
        p2 =(n*100.0f/size);
        // estimate MOS-value
        B = jb_guess_mos(p2,d2,codec);
        if (B > A) {
            p = p2;
            d = d2;
            A = B;
        }
        d1 = d2;
        //find next delay != delay so the same delay isn't calculated twice
        //don't look further if we have seen half of the history
        while((d2>=d1) && ((n*2)<max_index) ) {
            n++;
            d2 = jb->hist_sorted_delay[(max_index-n)] - jb->min;
        }
    }
    //the targeted size of the jitterbuffer
    if (jb->settings.min_jb && (jb->settings.min_jb > d) ) {
        jb->target = jb->min + jb->settings.min_jb;
    }
    else if (jb->settings.max_jb && (jb->settings.max_jb > d) ) {
        jb->target = jb->min + jb->settings.max_jb;
    }
    else {
        jb->target = jb->min + d;
    }
}


/***********
 * if there is a nonvoice frame it will be returned [*data] and the frame
 * will be made free
 */
static int get_control(jitterbuffer *jb, void **data)
{
    jb_frame *frame;
    int result;

    frame = jb->controlframes;
    if (frame) {
        jb_dbg("gC");
        *data = frame->data;
        frame->data = NULL;
        jb->controlframes = frame->next;
        frame_free(frame);
        result = JB_OK;
    }
    else {
        result = JB_NOFRAME;
    }
    return result;
}


/***********
 * returns JB_OK if a frame is available and *data points to the packet
 * returns JB_NOFRAME if it's no time to play voice and or no frame available
 * returns JB_INTERP if interpolating is required
 * returns JB_EMPTY if no voice frame is in the jitterbuffer (only during silence)
 *
 * if the next frame is a silence frame we will go in silence-mode
 * each new instance of the jitterbuffer will start in silence mode
 * in silence mode we will set the jitterbuffer to the size we want
 * when we are not in silence mode get_voicecase will handle the rest.
 */
static int get_voice(jitterbuffer *jb, void **data, long now, long interpl)
{
    jb_frame *frame;
    long diff;
    int result;

    diff = jb->target - jb->current;

    //if the next frame is a silence frame, go in silence mode...
    if((get_next_frametype(jb, now - jb->current) == JB_TYPE_SILENCE) ) {
        jb_dbg("gs");
        frame = get_frame(jb, now - jb->current);
        *data = frame->data;
        frame->data = NULL;
        jb->info.silence =1;
        jb->silence_begin_ts = frame->ts;
        frame_free(frame);
        result = JB_OK;
    }
    else {
        if(jb->info.silence) { // we are in silence
            /*
             * During silence we can set the jitterbuffer size to the size
             * we want...
             */
            if (diff) {
                jb->current = jb->target;
            }
            frame = get_frame(jb, now - jb->current);
            if (frame) {
                if (jb->silence_begin_ts && frame->ts < jb->silence_begin_ts) {
                    jb_dbg("gL");
                    /* voice frame is late, next!*/
                    jb->info.frames_late++;
                    frame_free(frame);
                    result = get_voice(jb, data, now, interpl);
                }
                else {
                    jb_dbg("gP");
                    /* voice frame */
                    jb->info.silence = 0;
                    jb->silence_begin_ts = 0;
                    jb->next_voice_time = frame->ts + frame->ms;
                    jb->info.last_voice_ms = frame->ms;
                    *data = frame->data;
                    frame->data = NULL;
                    frame_free(frame);
                    result = JB_OK;
                }
            }
            else {      //no frame
                jb_dbg("gS");
                result = JB_EMPTY;
            }
        }
        else {   //voice case
            result = get_voicecase(jb,data,now,interpl,diff);
        }
    }
    return result;
}


/***********
 * The voicecase has four 'options'
 * - difference is way off, reset
 * - diff > 0, we may need to grow
 * - diff < 0, we may need to shrink
 * - everything else
 */
static int get_voicecase(jitterbuffer *jb, void **data, long now, long interpl, long diff)
{
    jb_frame *frame;
    int result;

    // * - difference is way off, reset
    if (diff > jb->settings.max_diff || -diff > jb->settings.max_diff) {
        jb_err("wakko diff in get_voicecase\n");
        reset(jb); //reset hist because the timestamps are wakko.
        result = JB_NOFRAME;
        //- diff > 0, we may need to grow
    }
    else if ((diff > 0) &&
             (now > (jb->last_adjustment + jb->settings.wait_grow)
              || (now + jb->current + interpl) < get_next_framets(jb) ) ) { //grow
        /* first try to grow */
        if (diff<interpl/2) {
            jb_dbg("ag");
            jb->current +=diff;
        }
        else {
            jb_dbg("aG");
            /* grow by interp frame len */
            jb->current += interpl;
        }
        jb->last_adjustment = now;
        result = get_voice(jb, data, now, interpl);
        //- diff < 0, we may need to shrink
    }
    else if ( (diff < 0)
              && (now > (jb->last_adjustment + jb->settings.wait_shrink))
              && ((-diff) > jb->settings.extra_delay) ) {
        /* now try to shrink
         * if there is a frame shrink by frame length
         * otherwise shrink by interpl
         */
        jb->last_adjustment = now;

        frame = get_frame(jb, now - jb->current);
        if(frame) {
            jb_dbg("as");
            /* shrink by frame size we're throwing out */
            jb->info.frames_dropped++;
            jb->current -= frame->ms;
            frame_free(frame);
        }
        else {
            jb_dbg("aS");
            /* shrink by interpl */
            jb->current -= interpl;
        }
        result = get_voice(jb, data, now, interpl);
    }
    else  {
        /* if it is not the time to play a result = JB_NOFRAME
         * else We try to play a frame if a frame is available
         * and not late it is played otherwise
         * if available it is dropped and the next is tried
         * last option is interpolating
         */
        if (now - jb->current < jb->next_voice_time) {
            jb_dbg("aN");
            result = JB_NOFRAME;
        }
        else {
            frame = get_frame(jb, now - jb->current);
            if (frame) { //there is a frame
                /* voice frame is late */
                if(frame->ts < jb->next_voice_time) {   //late
                    jb_dbg("aL");
                    jb->info.frames_late++;
                    frame_free(frame);
                    result = get_voice(jb, data, now, interpl);
                }
                else {
                    jb_dbg("aP");
                    /* normal case; return the frame, increment stuff */
                    *data = frame->data;
                    frame->data = NULL;
                    jb->next_voice_time = frame->ts + frame->ms;
                    jb->cnt_successive_interp = 0;
                    frame_free(frame);
                    result = JB_OK;
                }
            }
            else {   // no frame, thus interpolate
                jb->cnt_successive_interp++;
                /* assume silence instead of continuing to interpolate */
                if (jb->settings.max_successive_interp && jb->cnt_successive_interp >= jb->settings.max_successive_interp) {
                    jb->info.silence = 1;
                    jb->silence_begin_ts = jb->next_voice_time;
                }
                jb_dbg("aI");
                jb->next_voice_time += interpl;
                result = JB_INTERP;
            }
        }
    }
    return result;

}


/***********
 * if there are frames and next frame->ts is smaller or equal ts
 *   return type of next frame.
 * else return 0
 */
static int get_next_frametype(jitterbuffer *jb, long ts)
{
    jb_frame *frame;
    int result;

    result = 0;
    frame = jb->voiceframes;
    if (frame && frame->ts <= ts) {
        result = frame->type;
    }
    return result;
}


/***********
 * returns ts from next frame in jb->voiceframes
 * or returns LONG_MAX if there is no frame
 */
static long get_next_framets(jitterbuffer *jb)
{
    if (jb->voiceframes) {
        return jb->voiceframes->ts;
    }
    return LONG_MAX;
}


/***********
 * if there is a frame in jb->voiceframes and
 * has a timestamp smaller/equal to ts
 * this frame will be returned and
 * removed from the queue
 */
static jb_frame *get_frame(jitterbuffer *jb, long ts)
{
    jb_frame *frame;

    frame = jb->voiceframes;
    if (frame && frame->ts <= ts) {
        if(frame->next == frame) {
            jb->voiceframes = NULL;
        }
        else {
            /* remove this frame */
            frame->prev->next = frame->next;
            frame->next->prev = frame->prev;
            jb->voiceframes = frame->next;
        }
        return frame;
    }
    return NULL;
}

/***********
 * if there is a frame in jb->voiceframes
 * this frame will be unconditionally returned and
 * removed from the queue
 */
static jb_frame *get_all_frames(jitterbuffer *jb)
{
    jb_frame *frame;

    frame = jb->voiceframes;
    if (frame) {
        if(frame->next == frame) {
            jb->voiceframes = NULL;
        }
        else {
            /* remove this frame */
            frame->prev->next = frame->next;
            frame->next->prev = frame->prev;
            jb->voiceframes = frame->next;
        }
        return frame;
    }
    return NULL;
}


#endif // !(HAVE_SPEEX_DSP && HAVE_SPEEX_JB)