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Automatic bandwidth decisions get more conservative as rate increases.

This should prevent errors in the bandwidth detection from affecting quality
when we have enough bits to be close to transparent.

--- a/celt/celt.h

+++ b/celt/celt.h

@@ -58,7 +58,6 @@

    opus_val16 activity;

    opus_val16 music_prob;

    int        bandwidth;

-   int        opus_bandwidth;

 }AnalysisInfo;

 #define __celt_check_mode_ptr_ptr(ptr) ((ptr) + ((ptr) - (const CELTMode**)(ptr)))

--- a/src/analysis.c

+++ b/src/analysis.c

@@ -575,19 +575,7 @@

        printf("%f ", features[i]);

     printf("\n");*/

-    if (bandwidth<=12)

-       tonal->opus_bandwidth = OPUS_BANDWIDTH_NARROWBAND;

-    else if (bandwidth<=14)

-       tonal->opus_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;

-    else if (bandwidth<=16)

-       tonal->opus_bandwidth = OPUS_BANDWIDTH_WIDEBAND;

-    else if (bandwidth<=18)

-       tonal->opus_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;

-    else

-       tonal->opus_bandwidth = OPUS_BANDWIDTH_FULLBAND;

-

     info->bandwidth = bandwidth;

-    info->opus_bandwidth = tonal->opus_bandwidth;

     /*printf("%d %d\n", info->bandwidth, info->opus_bandwidth);*/

     info->noisiness = frame_noisiness;

     info->valid = 1;

--- a/src/analysis.h

+++ b/src/analysis.h

@@ -60,7 +60,6 @@

    int last_music;

    int last_transition;

    int count;

-   int opus_bandwidth;

    opus_val32   subframe_mem[3];

    int analysis_offset;

    float pspeech[DETECT_SIZE];

--- a/src/opus_encoder.c

+++ b/src/opus_encoder.c

@@ -941,9 +941,21 @@

     st->detected_bandwidth = 0;

     if (analysis_info->valid)

     {

+       int analysis_bandwidth;

        if (st->signal_type == OPUS_AUTO)

           st->voice_ratio = (int)floor(.5+100*(1-analysis_info->music_prob));

-       st->detected_bandwidth = analysis_info->opus_bandwidth;

+

+       analysis_bandwidth = analysis_info->bandwidth;

+       if (analysis_bandwidth<=12)

+          st->detected_bandwidth = OPUS_BANDWIDTH_NARROWBAND;

+       else if (analysis_bandwidth<=14)

+          st->detected_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;

+       else if (analysis_bandwidth<=16)

+          st->detected_bandwidth = OPUS_BANDWIDTH_WIDEBAND;

+       else if (analysis_bandwidth<=18)

+          st->detected_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;

+       else

+          st->detected_bandwidth = OPUS_BANDWIDTH_FULLBAND;

     }

 #endif

@@ -1217,12 +1229,24 @@

     /* Use detected bandwidth to reduce the encoded bandwidth. */

     if (st->detected_bandwidth && st->user_bandwidth == OPUS_AUTO)

     {

-       /* When operating in SILK/hybrid mode, we don't go below wideband to avoid

-          more complicated switches that require redundancy */

-       if (st->mode == MODE_CELT_ONLY)

-          st->bandwidth = IMIN(st->bandwidth, st->detected_bandwidth);

+       int min_detected_bandwidth;

+       /* Makes bandwidth detection more conservative just in case the detector

+          gets it wrong when we could have coded a high bandwidth transparently.

+          When operating in SILK/hybrid mode, we don't go below wideband to avoid

+          more complicated switches that require redundancy. */

+       if (st->bitrate_bps <= 18000*st->stream_channels && st->mode == MODE_CELT_ONLY)

+          min_detected_bandwidth = OPUS_BANDWIDTH_NARROWBAND;

+       else if (st->bitrate_bps <= 24000*st->stream_channels && st->mode == MODE_CELT_ONLY)

+          min_detected_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;

+       else if (st->bitrate_bps <= 30000*st->stream_channels)

+          min_detected_bandwidth = OPUS_BANDWIDTH_WIDEBAND;

+       else if (st->bitrate_bps <= 44000*st->stream_channels)

+          min_detected_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;

        else

-          st->bandwidth = IMIN(st->bandwidth, IMAX(OPUS_BANDWIDTH_WIDEBAND, st->detected_bandwidth));

+          min_detected_bandwidth = OPUS_BANDWIDTH_FULLBAND;

+

+       st->detected_bandwidth = IMAX(st->detected_bandwidth, min_detected_bandwidth);

+       st->bandwidth = IMIN(st->bandwidth, st->detected_bandwidth);

     }

 #endif

     celt_encoder_ctl(celt_enc, OPUS_SET_LSB_DEPTH(lsb_depth));