@@ -43,6 +43,7 @@

 #define MAX_ELEM_ID 16

 #define TNS_MAX_ORDER 20

+#define MAX_LTP_LONG_SFB 40

 enum RawDataBlockType {

     TYPE_SCE,

@@ -131,6 +132,16 @@ typedef struct {

 #define SCALE_DIFF_ZERO  60    ///< codebook index corresponding to zero scalefactor indices difference

 /**

+ * Long Term Prediction

+ */

+typedef struct {

+    int8_t present;

+    int16_t lag;

+    float coef;

+    int8_t used[MAX_LTP_LONG_SFB];

+} LongTermPrediction;

+

+/**

  * Individual Channel Stream

  */

 typedef struct {

@@ -139,6 +150,7 @@ typedef struct {

     uint8_t use_kb_window[2];   ///< If set, use Kaiser-Bessel window, otherwise use a sinus window.

     int num_window_groups;

     uint8_t group_len[8];

+    LongTermPrediction ltp;

     const uint16_t *swb_offset; ///< table of offsets to the lowest spectral coefficient of a scalefactor band, sfb, for a particular window

     const uint8_t *swb_sizes;   ///< table of scalefactor band sizes for a particular window

     int num_swb;                ///< number of scalefactor window bands

@@ -206,14 +218,15 @@ typedef struct {

     IndividualChannelStream ics;

     TemporalNoiseShaping tns;

     Pulse pulse;

-    enum BandType band_type[128];             ///< band types

-    int band_type_run_end[120];               ///< band type run end points

-    float sf[120];                            ///< scalefactors

-    int sf_idx[128];                          ///< scalefactor indices (used by encoder)

-    uint8_t zeroes[128];                      ///< band is not coded (used by encoder)

-    DECLARE_ALIGNED(16, float, coeffs)[1024]; ///< coefficients for IMDCT

-    DECLARE_ALIGNED(16, float, saved)[1024];  ///< overlap

-    DECLARE_ALIGNED(16, float, ret)[2048];    ///< PCM output

+    enum BandType band_type[128];                   ///< band types

+    int band_type_run_end[120];                     ///< band type run end points

+    float sf[120];                                  ///< scalefactors

+    int sf_idx[128];                                ///< scalefactor indices (used by encoder)

+    uint8_t zeroes[128];                            ///< band is not coded (used by encoder)

+    DECLARE_ALIGNED(16, float,   coeffs)[1024];     ///< coefficients for IMDCT

+    DECLARE_ALIGNED(16, float,   saved)[1024];      ///< overlap

+    DECLARE_ALIGNED(16, float,   ret)[2048];        ///< PCM output

+    DECLARE_ALIGNED(16, int16_t, ltp_state)[3072];  ///< time signal for LTP

     PredictorState predictor_state[MAX_PREDICTORS];

 } SingleChannelElement;

@@ -259,7 +272,7 @@ typedef struct {

      * @defgroup temporary aligned temporary buffers (We do not want to have these on the stack.)

      * @{

      */

-    DECLARE_ALIGNED(16, float, buf_mdct)[1024];

+    DECLARE_ALIGNED(16, float, buf_mdct)[2048];

     /** @} */

     /**

@@ -268,6 +281,7 @@ typedef struct {

      */

     FFTContext mdct;

     FFTContext mdct_small;

+    FFTContext mdct_ltp;

     DSPContext dsp;

     FmtConvertContext fmt_conv;

     int random_state;

@@ -42,7 +42,7 @@

  * Y                    filterbank - standard

  * N (code in SoC repo) filterbank - Scalable Sample Rate

  * Y                    Temporal Noise Shaping

- * N (code in SoC repo) Long Term Prediction

+ * Y                    Long Term Prediction

  * Y                    intensity stereo

  * Y                    channel coupling

  * Y                    frequency domain prediction

@@ -478,6 +478,7 @@ static int decode_audio_specific_config(AACContext *ac,

     switch (m4ac->object_type) {

     case AOT_AAC_MAIN:

     case AOT_AAC_LC:

+    case AOT_AAC_LTP:

         if (decode_ga_specific_config(ac, avctx, &gb, m4ac, m4ac->chan_config))

             return -1;

         break;

@@ -580,8 +581,9 @@ static av_cold int aac_decode_init(AVCodecContext *avctx)

                     ff_aac_scalefactor_code, sizeof(ff_aac_scalefactor_code[0]), sizeof(ff_aac_scalefactor_code[0]),

                     352);

-    ff_mdct_init(&ac->mdct, 11, 1, 1.0);

-    ff_mdct_init(&ac->mdct_small, 8, 1, 1.0);

+    ff_mdct_init(&ac->mdct,       11, 1, 1.0);

+    ff_mdct_init(&ac->mdct_small,  8, 1, 1.0);

+    ff_mdct_init(&ac->mdct_ltp,   11, 0, 1.0);

     // window initialization

     ff_kbd_window_init(ff_aac_kbd_long_1024, 4.0, 1024);

     ff_kbd_window_init(ff_aac_kbd_short_128, 6.0, 128);

@@ -631,6 +633,20 @@ static int decode_prediction(AACContext *ac, IndividualChannelStream *ics,

 }

 /**

+ * Decode Long Term Prediction data; reference: table 4.xx.

+ */

+static void decode_ltp(AACContext *ac, LongTermPrediction *ltp,

+                       GetBitContext *gb, uint8_t max_sfb)

+{

+    int sfb;

+

+    ltp->lag  = get_bits(gb, 11);

+    ltp->coef = ltp_coef[get_bits(gb, 3)] * ac->sf_scale;

+    for (sfb = 0; sfb < FFMIN(max_sfb, MAX_LTP_LONG_SFB); sfb++)

+        ltp->used[sfb] = get_bits1(gb);

+}

+

+/**

  * Decode Individual Channel Stream info; reference: table 4.6.

  *

  * @param   common_window   Channels have independent [0], or shared [1], Individual Channel Stream information.

@@ -684,9 +700,8 @@ static int decode_ics_info(AACContext *ac, IndividualChannelStream *ics,

                 memset(ics, 0, sizeof(IndividualChannelStream));

                 return -1;

             } else {

-                av_log_missing_feature(ac->avctx, "Predictor bit set but LTP is", 1);

-                memset(ics, 0, sizeof(IndividualChannelStream));

-                return -1;

+                if ((ics->ltp.present = get_bits(gb, 1)))

+                    decode_ltp(ac, &ics->ltp, gb, ics->max_sfb);

             }

         }

     }

@@ -1420,6 +1435,9 @@ static int decode_cpe(AACContext *ac, GetBitContext *gb, ChannelElement *cpe)

         i = cpe->ch[1].ics.use_kb_window[0];

         cpe->ch[1].ics = cpe->ch[0].ics;

         cpe->ch[1].ics.use_kb_window[1] = i;

+        if (cpe->ch[1].ics.predictor_present && (ac->m4ac.object_type != AOT_AAC_MAIN))

+            if ((cpe->ch[1].ics.ltp.present = get_bits(gb, 1)))

+                decode_ltp(ac, &cpe->ch[1].ics.ltp, gb, cpe->ch[1].ics.max_sfb);

         ms_present = get_bits(gb, 2);

         if (ms_present == 3) {

             av_log(ac->avctx, AV_LOG_ERROR, "ms_present = 3 is reserved.\n");

@@ -1659,6 +1677,7 @@ static void apply_tns(float coef[1024], TemporalNoiseShaping *tns,

     int w, filt, m, i;

     int bottom, top, order, start, end, size, inc;

     float lpc[TNS_MAX_ORDER];

+    float tmp[TNS_MAX_ORDER];

     for (w = 0; w < ics->num_windows; w++) {

         bottom = ics->num_swb;

@@ -1684,15 +1703,119 @@ static void apply_tns(float coef[1024], TemporalNoiseShaping *tns,

             }

             start += w * 128;

-            // ar filter

-            for (m = 0; m < size; m++, start += inc)

-                for (i = 1; i <= FFMIN(m, order); i++)

-                    coef[start] -= coef[start - i * inc] * lpc[i - 1];

+            if (decode) {

+                // ar filter

+                for (m = 0; m < size; m++, start += inc)

+                    for (i = 1; i <= FFMIN(m, order); i++)

+                        coef[start] -= coef[start - i * inc] * lpc[i - 1];

+            } else {

+                // ma filter

+                for (m = 0; m < size; m++, start += inc) {

+                    tmp[0] = coef[start];

+                    for (i = 1; i <= FFMIN(m, order); i++)

+                        coef[start] += tmp[i] * lpc[i - 1];

+                    for (i = order; i > 0; i--)

+                        tmp[i] = tmp[i - 1];

+                }

+            }

         }

     }

 }

 /**

+ *  Apply windowing and MDCT to obtain the spectral

+ *  coefficient from the predicted sample by LTP.

+ */

+static void windowing_and_mdct_ltp(AACContext *ac, float *out,

+                                   float *in, IndividualChannelStream *ics)

+{

+    const float *lwindow      = ics->use_kb_window[0] ? ff_aac_kbd_long_1024 : ff_sine_1024;

+    const float *swindow      = ics->use_kb_window[0] ? ff_aac_kbd_short_128 : ff_sine_128;

+    const float *lwindow_prev = ics->use_kb_window[1] ? ff_aac_kbd_long_1024 : ff_sine_1024;

+    const float *swindow_prev = ics->use_kb_window[1] ? ff_aac_kbd_short_128 : ff_sine_128;

+

+    if (ics->window_sequence[0] != LONG_STOP_SEQUENCE) {

+        ac->dsp.vector_fmul(in, in, lwindow_prev, 1024);

+    } else {

+        memset(in, 0, 448 * sizeof(float));

+        ac->dsp.vector_fmul(in + 448, in + 448, swindow_prev, 128);

+        memcpy(in + 576, in + 576, 448 * sizeof(float));

+    }

+    if (ics->window_sequence[0] != LONG_START_SEQUENCE) {

+        ac->dsp.vector_fmul_reverse(in + 1024, in + 1024, lwindow, 1024);

+    } else {

+        memcpy(in + 1024, in + 1024, 448 * sizeof(float));

+        ac->dsp.vector_fmul_reverse(in + 1024 + 448, in + 1024 + 448, swindow, 128);

+        memset(in + 1024 + 576, 0, 448 * sizeof(float));

+    }

+    ff_mdct_calc(&ac->mdct_ltp, out, in);

+}

+

+/**

+ * Apply the long term prediction

+ */

+static void apply_ltp(AACContext *ac, SingleChannelElement *sce)

+{

+    const LongTermPrediction *ltp = &sce->ics.ltp;

+    const uint16_t *offsets = sce->ics.swb_offset;

+    int i, sfb;

+

+    if (sce->ics.window_sequence[0] != EIGHT_SHORT_SEQUENCE) {

+        float *predTime = ac->buf_mdct;

+        float *predFreq = sce->ret;

+        int16_t num_samples = 2048;

+

+        if (ltp->lag < 1024)

+            num_samples = ltp->lag + 1024;

+        for (i = 0; i < num_samples; i++)

+            predTime[i] = sce->ltp_state[i + 2048 - ltp->lag] * ltp->coef;

+        memset(&predTime[i], 0, (2048 - i) * sizeof(float));

+

+        windowing_and_mdct_ltp(ac, predFreq, predTime, &sce->ics);

+

+        if (sce->tns.present)

+            apply_tns(predFreq, &sce->tns, &sce->ics, 0);

+

+        for (sfb = 0; sfb < FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB); sfb++)

+            if (ltp->used[sfb])

+                for (i = offsets[sfb]; i < offsets[sfb + 1]; i++)

+                    sce->coeffs[i] += predFreq[i];

+    }

+}

+

+/**

+ * Update the LTP buffer for next frame

+ */

+static void update_ltp(AACContext *ac, SingleChannelElement *sce)

+{

+    IndividualChannelStream *ics = &sce->ics;

+    float *saved     = sce->saved;

+    float *saved_ltp = sce->coeffs;

+    const float *lwindow = ics->use_kb_window[0] ? ff_aac_kbd_long_1024 : ff_sine_1024;

+    const float *swindow = ics->use_kb_window[0] ? ff_aac_kbd_short_128 : ff_sine_128;

+    int i;

+

+    for (i = 0; i < 512; i++)

+        ac->buf_mdct[1535 - i] = ac->buf_mdct[512 + i];

+

+    if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {

+        memcpy(saved_ltp,       saved, 512 * sizeof(float));

+        memset(saved_ltp + 576, 0,     448 * sizeof(float));

+        ac->dsp.vector_fmul_reverse(saved_ltp + 448, ac->buf_mdct + 960,     swindow,     128);

+    } else if (ics->window_sequence[0] == LONG_START_SEQUENCE) {

+        memcpy(saved_ltp,       ac->buf_mdct + 512, 448 * sizeof(float));

+        memset(saved_ltp + 576, 0,                  448 * sizeof(float));

+        ac->dsp.vector_fmul_reverse(saved_ltp + 448, ac->buf_mdct + 960,     swindow,     128);

+    } else { // LONG_STOP or ONLY_LONG

+        ac->dsp.vector_fmul_reverse(saved_ltp,       ac->buf_mdct + 512,     lwindow,     1024);

+    }

+

+    memcpy(sce->ltp_state, &sce->ltp_state[1024], 1024 * sizeof(int16_t));

+    ac->fmt_conv.float_to_int16(&(sce->ltp_state[1024]), sce->ret,  1024);

+    ac->fmt_conv.float_to_int16(&(sce->ltp_state[2048]), saved_ltp, 1024);

+}

+

+/**

  * Conduct IMDCT and windowing.

  */

 static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce)

@@ -1857,6 +1980,14 @@ static void spectral_to_sample(AACContext *ac)

             if (che) {

                 if (type <= TYPE_CPE)

                     apply_channel_coupling(ac, che, type, i, BEFORE_TNS, apply_dependent_coupling);

+                if (ac->m4ac.object_type == AOT_AAC_LTP) {

+                    if (che->ch[0].ics.predictor_present) {

+                        if (che->ch[0].ics.ltp.present)

+                            apply_ltp(ac, &che->ch[0]);

+                        if (che->ch[1].ics.ltp.present && type == TYPE_CPE)

+                            apply_ltp(ac, &che->ch[1]);

+                    }

+                }

                 if (che->ch[0].tns.present)

                     apply_tns(che->ch[0].coeffs, &che->ch[0].tns, &che->ch[0].ics, 1);

                 if (che->ch[1].tns.present)

@@ -1865,8 +1996,12 @@ static void spectral_to_sample(AACContext *ac)

                     apply_channel_coupling(ac, che, type, i, BETWEEN_TNS_AND_IMDCT, apply_dependent_coupling);

                 if (type != TYPE_CCE || che->coup.coupling_point == AFTER_IMDCT) {

                     imdct_and_windowing(ac, &che->ch[0]);

+                    if (ac->m4ac.object_type == AOT_AAC_LTP)

+                        update_ltp(ac, &che->ch[0]);

                     if (type == TYPE_CPE) {

                         imdct_and_windowing(ac, &che->ch[1]);

+                        if (ac->m4ac.object_type == AOT_AAC_LTP)

+                            update_ltp(ac, &che->ch[1]);

                     }

                     if (ac->m4ac.sbr > 0) {

                         ff_sbr_apply(ac, &che->sbr, type, che->ch[0].ret, che->ch[1].ret);

@@ -2080,6 +2215,7 @@ static av_cold int aac_decode_close(AVCodecContext *avctx)

     ff_mdct_end(&ac->mdct);

     ff_mdct_end(&ac->mdct_small);

+    ff_mdct_end(&ac->mdct_ltp);

     return 0;

 }

@@ -35,6 +35,14 @@

 #include <stdint.h>

+/* @name ltp_coef

+ * Table of the LTP coefficient (multiplied by 2)

+ */

+static const float ltp_coef[8] = {

+     1.141658,    1.393232,    1.626008,    1.822608,

+     1.969800,    2.135788,    2.2389202,   2.739066,

+};

+

 /* @name tns_tmp2_map

  * Tables of the tmp2[] arrays of LPC coefficients used for TNS.

  * The suffix _M_N[] indicate the values of coef_compress and coef_res

@@ -57,7 +57,7 @@ enum AudioObjectType {

     AOT_AAC_MAIN,              ///< Y                       Main

     AOT_AAC_LC,                ///< Y                       Low Complexity

     AOT_AAC_SSR,               ///< N (code in SoC repo)    Scalable Sample Rate

-    AOT_AAC_LTP,               ///< N (code in SoC repo)    Long Term Prediction

+    AOT_AAC_LTP,               ///< Y                       Long Term Prediction

     AOT_SBR,                   ///< Y                       Spectral Band Replication

     AOT_AAC_SCALABLE,          ///< N                       Scalable

     AOT_TWINVQ,                ///< N                       Twin Vector Quantizer