diff --git a/apps/decoder.c b/apps/decoder.c
index b54ad4b92e4eff6053d767b70425a6c701403bfb..5525c46a0b5a35accf639bce03899991997a3fb4 100644
--- a/apps/decoder.c
+++ b/apps/decoder.c
@@ -2905,7 +2905,14 @@ static ivas_error decodeVoIP(
         }
         vec_pos_update = ( vec_pos_update + 1 ) % vec_pos_len;
         frame++;
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+        if ( vec_pos_update == 0 )
+        {
+            systemTime_ms += vec_pos_len * systemTimeInc_ms;
+        }
+#else
         systemTime_ms += systemTimeInc_ms;
+#endif
 
 #ifdef WMOPS
         update_mem();
@@ -2913,6 +2920,94 @@ static ivas_error decodeVoIP(
 #endif
     }
 
+
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+    int16_t nSamplesFlushed = 0;
+
+    /* decode and get samples */
+#ifdef SPLIT_REND_WITH_HEAD_ROT
+    if ( ( error = IVAS_DEC_Flush( hIvasDec, nOutSamples, IVAS_DEC_PCM_INT16, (void *) pcmBuf, &nSamplesFlushed ) ) != IVAS_ERR_OK )
+#else
+    if ( ( error = IVAS_DEC_Flush( hIvasDec, nOutSamples, pcmBuf, &nSamplesFlushed ) ) != IVAS_ERR_OK )
+#endif
+    {
+        fprintf( stderr, "\nError in IVAS_DEC_VoIP_Flush: %s\n", IVAS_DEC_GetErrorMessage( error ) );
+        goto cleanup;
+    }
+
+    if ( nSamplesFlushed )
+    {
+        /* Write current frame */
+        if ( ( error = AudioFileWriter_write( afWriter, pcmBuf, nSamplesFlushed * nOutChannels ) ) != IVAS_ERR_OK )
+        {
+            fprintf( stderr, "\nOutput audio file writer error\n" );
+            goto cleanup;
+        }
+
+        /* Write ISm metadata to external file(s) */
+        if ( decodedGoodFrame && arg.outputConfig == IVAS_AUDIO_CONFIG_EXTERNAL )
+        {
+            if ( bsFormat == IVAS_DEC_BS_OBJ || bsFormat == IVAS_DEC_BS_MASA_ISM || bsFormat == IVAS_DEC_BS_SBA_ISM )
+            {
+                if ( ( error = IVAS_DEC_GetNumObjects( hIvasDec, &numObj ) ) != IVAS_ERR_OK )
+                {
+                    fprintf( stderr, "\nError in IVAS_DEC_GetNumObjects: %s\n", IVAS_DEC_GetErrorMessage( error ) );
+                    goto cleanup;
+                }
+
+                for ( i = 0; i < numObj; ++i )
+                {
+                    IVAS_ISM_METADATA IsmMetadata;
+
+                    if ( ( error = IVAS_DEC_GetObjectMetadata( hIvasDec, &IsmMetadata, 0, i ) ) != IVAS_ERR_OK )
+                    {
+                        fprintf( stderr, "\nError in IVAS_DEC_GetObjectMetadata: %s\n", IVAS_DEC_GetErrorMessage( error ) );
+                        goto cleanup;
+                    }
+
+                    if ( ( IsmFileWriter_writeFrame( IsmMetadata, ismWriters[i] ) ) != IVAS_ERR_OK )
+                    {
+                        fprintf( stderr, "\nError writing ISM metadata to file %s\n", IsmFileWriter_getFilePath( ismWriters[i] ) );
+                        goto cleanup;
+                    }
+                }
+            }
+
+            if ( bsFormat == IVAS_DEC_BS_MASA || bsFormat == IVAS_DEC_BS_MASA_ISM )
+            {
+                IVAS_MASA_DECODER_EXT_OUT_META_HANDLE hMasaExtOutMeta;
+#ifdef NONBE_FIX_984_OMASA_EXT_OUTPUT
+                int16_t fullDelayNumSamples[3];
+                float delayMs;
+
+                /* delayNumSamples is zeroed, and delayNumSamples_orig is updated only on first good frame, so need to re-fetch delay info */
+                if ( ( error = IVAS_DEC_GetDelay( hIvasDec, fullDelayNumSamples, &delayTimeScale ) ) != IVAS_ERR_OK )
+                {
+                    fprintf( stderr, "\nUnable to get delay of decoder: %s\n", ivas_error_to_string( error ) );
+                }
+#endif
+                if ( ( error = IVAS_DEC_GetMasaMetadata( hIvasDec, &hMasaExtOutMeta, 0 ) ) != IVAS_ERR_OK )
+                {
+                    fprintf( stderr, "\nError in IVAS_DEC_GetMasaMetadata: %s\n", IVAS_DEC_GetErrorMessage( error ) );
+                    goto cleanup;
+                }
+
+#ifdef NONBE_FIX_984_OMASA_EXT_OUTPUT
+                delayMs = (float) ( fullDelayNumSamples[0] ) / (float) ( delayTimeScale );
+                if ( ( error = MasaFileWriter_writeFrame( masaWriter, hMasaExtOutMeta, &delayMs ) ) != IVAS_ERR_OK )
+#else
+                if ( ( error = MasaFileWriter_writeFrame( masaWriter, hMasaExtOutMeta ) ) != IVAS_ERR_OK )
+#endif
+                {
+                    fprintf( stderr, "\nError writing MASA metadata to file: %s\n", MasaFileWriter_getFilePath( masaWriter ) );
+                    goto cleanup;
+                }
+            }
+        }
+    }
+#endif
+
+
     /*------------------------------------------------------------------------------------------*
      * Add zeros at the end to have equal length of synthesized signals
      *------------------------------------------------------------------------------------------*/
diff --git a/lib_com/options.h b/lib_com/options.h
index 16880c701277224351efb1904b4368cf5a671066..9b03463a181acdc36ccd7594187aac3a70b3d32e 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -143,6 +143,8 @@
 
 /* ################### Start FIXES switches ########################### */
 
+#define NONBE_FIX_864_JBM_RENDER_FRAMESIZE                    /* FhG: issue #864: fix different behaviour of JBM TSM with different render frame sizes */
+
 
 /* #################### End FIXES switches ############################ */
 
diff --git a/lib_dec/lib_dec.c b/lib_dec/lib_dec.c
index d7f3e5f6ec9f26db9b0372565edbddb3040eddc5..64f1baa800c737f585fca733c1cbb65a6794e782 100644
--- a/lib_dec/lib_dec.c
+++ b/lib_dec/lib_dec.c
@@ -57,6 +57,9 @@ struct IVAS_DEC_VOIP
     uint16_t lastDecodedWasActive;
     JB4_DATAUNIT_HANDLE hCurrentDataUnit; /* Points to the currently processed data unit */
     uint16_t *bs_conversion_buf;          /* Buffer for bitstream conversion from packed to serial */
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+    int16_t nSamplesRendered20ms; /* how many samples have been rendered since the last 20ms render border*/
+#endif
 #ifdef SUPPORT_JBM_TRACEFILE
     IVAS_JBM_TRACE_DATA JbmTraceData;
 #endif
@@ -78,6 +81,9 @@ struct IVAS_DEC
     bool Opt_VOIP;           /* flag indicating VOIP mode with JBM */
     int16_t tsm_scale;       /* scale for TSM operation */
     int16_t tsm_max_scaling;
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+    int16_t timeScalingDone; /* have we done already one TSM in a 20ms frame? */
+#endif
     float tsm_quality;
     float *apaExecBuffer; /* Buffer for APA scaling */
     PCMDSP_APA_HANDLE hTimeScaler;
@@ -112,7 +118,9 @@ static ivas_error IVAS_DEC_RendererFeedTcSamples( IVAS_DEC_HANDLE hIvasDec, cons
 static ivas_error IVAS_DEC_GetRenderedSamples( IVAS_DEC_HANDLE hIvasDec, const uint16_t nSamplesForRendering, uint16_t *nSamplesRendered, uint16_t *nSamplesAvailableNext, int16_t *pcmBuf );
 static ivas_error IVAS_DEC_GetBufferedNumberOfSamples( IVAS_DEC_HANDLE hIvasDec, int16_t *nSamplesBuffered );
 static int16_t get_render_frame_size_ms( IVAS_RENDER_FRAMESIZE render_framesize );
-
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+static void update_voip_rendered20ms( IVAS_DEC_HANDLE hIvasDec, const int16_t nSamplesRendered );
+#endif
 
 /*---------------------------------------------------------------------*
  * IVAS_DEC_Open()
@@ -149,6 +157,9 @@ ivas_error IVAS_DEC_Open(
     hIvasDec->tsm_scale = 100;
     hIvasDec->tsm_max_scaling = 0;
     hIvasDec->tsm_quality = 1.0f;
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+    hIvasDec->timeScalingDone = 0;
+#endif
     hIvasDec->needNewFrame = false;
     hIvasDec->nTransportChannelsOld = 0;
     hIvasDec->nSamplesAvailableNext = 0;
@@ -651,6 +662,9 @@ ivas_error IVAS_DEC_EnableVoIP(
     hIvasDec->hVoIP->lastDecodedWasActive = 0;
     hIvasDec->hVoIP->hCurrentDataUnit = NULL;
     hIvasDec->hVoIP->nSamplesFrame = (uint16_t) ( hDecoderConfig->output_Fs / FRAMES_PER_SEC );
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+    hIvasDec->hVoIP->nSamplesRendered20ms = 0;
+#endif
 
 #define WMC_TOOL_SKIP
     /* Bitstream conversion is not counted towards complexity and memory usage */
@@ -887,18 +901,27 @@ ivas_error IVAS_DEC_GetSamples(
 
                     assert( nTimeScalerOutSamples <= APA_BUF );
                     nSamplesTcsScaled = nTimeScalerOutSamples / nTransportChannels;
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+                    hIvasDec->timeScalingDone = 1;
+#endif
                 }
                 else
                 {
                     nSamplesTcsScaled = hIvasDec->nSamplesFrame;
                 }
 
+#ifdef DEBUG_MODE_JBM
+                dbgwrite( &nTimeScalerOutSamples, sizeof( uint16_t ), 1, 1, "./res/JBM_nTimeScaleOutSamples.dat" );
+#endif
                 /* Feed decoded transport channels samples to the renderer */
                 if ( ( error = IVAS_DEC_RendererFeedTcSamples( hIvasDec, nSamplesTcsScaled, &nResidualSamples, hIvasDec->apaExecBuffer ) ) != IVAS_ERR_OK )
                 {
                     return error;
                 }
 
+#ifdef DEBUG_MODE_JBM
+                dbgwrite( &nResidualSamples, sizeof( int16_t ), 1, 1, "./res/JBM_nResidualSamples.dat" );
+#endif
                 if ( hIvasDec->st_ivas->hDecoderConfig->Opt_tsm )
                 {
                     /* feed residual samples to TSM for the next call */
@@ -1131,6 +1154,9 @@ static ivas_error IVAS_DEC_GetBufferedNumberOfSamples(
     if ( hIvasDec->st_ivas->hTcBuffer != NULL )
     {
         *nSamplesBuffered = hIvasDec->st_ivas->hTcBuffer->n_samples_buffered - hIvasDec->st_ivas->hTcBuffer->n_samples_rendered;
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+        *nSamplesBuffered += hIvasDec->hVoIP->nSamplesRendered20ms;
+#endif
     }
 
     return IVAS_ERR_OK;
@@ -2117,7 +2143,9 @@ ivas_error IVAS_DEC_VoIP_GetSamples(
     uint32_t extBufferedTime_ms, scale, maxScaling;
     JB4_DATAUNIT_HANDLE dataUnit;
     uint16_t extBufferedSamples;
+#ifndef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
     int16_t timeScalingDone;
+#endif
     int16_t result;
     ivas_error error;
     int16_t nSamplesRendered;
@@ -2126,7 +2154,9 @@ ivas_error IVAS_DEC_VoIP_GetSamples(
     st_ivas = hIvasDec->st_ivas;
     hDecoderConfig = st_ivas->hDecoderConfig;
     hVoIP = hIvasDec->hVoIP;
+#ifndef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
     timeScalingDone = 0;
+#endif
     nOutChannels = (uint8_t) st_ivas->hDecoderConfig->nchan_out;
     nSamplesRendered = 0;
 
@@ -2150,10 +2180,15 @@ ivas_error IVAS_DEC_VoIP_GetSamples(
                 }
             }
 
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+            extBufferedSamples = nSamplesBuffered;
+#else
             extBufferedSamples = nSamplesRendered + nSamplesBuffered;
+#endif
             extBufferedTime_ms = extBufferedSamples * 1000 / hDecoderConfig->output_Fs;
             dataUnit = NULL;
 
+
             /* pop one access unit from the jitter buffer */
             result = JB4_PopDataUnit( hVoIP->hJBM, systemTimestamp_ms, extBufferedTime_ms, &dataUnit, &scale, &maxScaling );
             if ( result != 0 )
@@ -2162,17 +2197,30 @@ ivas_error IVAS_DEC_VoIP_GetSamples(
             }
             maxScaling = maxScaling * hDecoderConfig->output_Fs / 1000;
 
+#ifdef DEBUG_MODE_JBM
+            dbgwrite( &extBufferedSamples, sizeof( uint16_t ), 1, 1, "./res/JBM_extBufferedSamples.dat" );
+            dbgwrite( &systemTimestamp_ms, sizeof( uint32_t ), 1, 1, "./res/JBM_systemTimestamp.dat" );
+            dbgwrite( &scale, sizeof( uint32_t ), 1, 1, "./res/JBM_scale.dat" );
+            dbgwrite( &maxScaling, sizeof( uint32_t ), 1, 1, "./res/JBM_maxScale.dat" );
+#endif
+
             /* avoid time scaling multiple times in one sound card slot */
             if ( scale != 100U )
             {
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+                if ( hIvasDec->timeScalingDone )
+#else
                 if ( timeScalingDone )
+#endif
                 {
                     scale = 100;
                 }
+#ifndef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
                 else
                 {
                     timeScalingDone = 1;
                 }
+#endif
             }
 
             /* limit scale to range supported by time scaler */
@@ -2257,6 +2305,9 @@ ivas_error IVAS_DEC_VoIP_GetSamples(
             nSamplesRendered += nSamplesToZero;
             hIvasDec->nSamplesRendered += nSamplesToZero;
             hIvasDec->nSamplesAvailableNext -= nSamplesToZero;
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+            update_voip_rendered20ms( hIvasDec, nSamplesToZero );
+#endif
         }
         else
         {
@@ -2271,12 +2322,37 @@ ivas_error IVAS_DEC_VoIP_GetSamples(
             }
 
             nSamplesRendered += nSamplesRendered_loop;
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+            update_voip_rendered20ms( hIvasDec, nSamplesRendered_loop );
+#endif
         }
     }
 
     return IVAS_ERR_OK;
 }
 
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+/*---------------------------------------------------------------------*
+ * update_voip_rendered20ms( )
+ *
+ * Function to flush remaining audio in VoIP
+ *---------------------------------------------------------------------*/
+
+static void update_voip_rendered20ms(
+    IVAS_DEC_HANDLE hIvasDec,
+    const int16_t nSamplesRendered )
+{
+    int16_t nSamplesRenderedTotal;
+    nSamplesRenderedTotal = hIvasDec->hVoIP->nSamplesRendered20ms + nSamplesRendered;
+    /* we have crossed a 20ms border, reset the time scaling done flag */
+    if ( nSamplesRenderedTotal >= hIvasDec->hVoIP->nSamplesFrame )
+    {
+        hIvasDec->timeScalingDone = 0;
+    }
+    hIvasDec->hVoIP->nSamplesRendered20ms = nSamplesRenderedTotal % hIvasDec->hVoIP->nSamplesFrame;
+}
+
+#endif
 
 /*---------------------------------------------------------------------*
  * IVAS_DEC_VoIP_Flush( )
@@ -2300,8 +2376,19 @@ ivas_error IVAS_DEC_Flush(
     nSamplesToRender = (uint16_t) *nSamplesFlushed;
 
     /* render IVAS frames  */
-    error = IVAS_DEC_GetRenderedSamples( hIvasDec, nSamplesToRender, &nSamplesFlushedLocal, &hIvasDec->nSamplesAvailableNext, pcmBuf );
-
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+    error = IVAS_ERR_OK;
+    if ( nSamplesToRender > 0 && hIvasDec->st_ivas->ivas_format != MONO_FORMAT )
+    {
+#endif
+        error = IVAS_DEC_GetRenderedSamples( hIvasDec, nSamplesToRender, &nSamplesFlushedLocal, &hIvasDec->nSamplesAvailableNext, pcmBuf );
+#ifdef NONBE_FIX_864_JBM_RENDER_FRAMESIZE
+    }
+    else
+    {
+        *nSamplesFlushed = 0;
+    }
+#endif
     return error;
 }